which needle size for rejeunesse

Common Specifications

In the field of hyaluronic acid injections, over 90% of individuals seeking aesthetic treatments focus 100% of their attention on the brand and price. However, a key factor that truly determines the immediate pain level, post-procedure recovery speed, and even the final shaping precision is widely overlooked—that is the needle size. This small metal tube, with an internal diameter difference that might be only 0.05 millimeters, directly controls the physical foundation of the entire injection process. Data indicates that when selecting a needle for medium-density hyaluronic acid like Rejeunesse, switching from a 27G to a 30G needle can reduce the pain sensation at the moment of insertion by approximately 15%-20%, and significantly decrease the probability of subcutaneous capillary damage (i.e., bruising risk) from over 25% to below 10%.

27G vs. 30G

Taking medium-density hyaluronic acid like Rejeunesse as an example, its viscosity range is typically between 5,000 to 20,000 centipoise (cP). When it passes through a needle with an internal diameter of only 0.16 millimeters (30G), the pressure the doctor needs to apply for injection is nearly 1.5 times higher than when using a needle with an internal diameter of 0.21 millimeters (27G). This pressure difference directly translates into a core clinical distinction: the 30G needle reduces the probability of immediate pinpoint bleeding from about 25% with the 27G needle to below 10%, but the trade-off is that the time to inject the same 0.1 milliliters of gel may extend from 3 seconds to 5 seconds.

1. Different Thickness

The “G” value of a needle directly corresponds to its diameter. A higher number indicates a finer needle. The actual outer diameter of a 27G needle is approximately 0.41 millimeters, while the 30G needle is much finer, only 0.31 millimeters. Although it’s only finer by 0.1 millimeters, the skin wound area it leaves is smaller by 42%.

The most critical difference lies in the internal channel. The internal diameter of a 27G needle (the aperture through which the hyaluronic acid flows) is about 0.21 millimeters, while the 30G internal diameter is about 0.16 millimeters. Calculating the cross-sectional area, the channel space of the 30G needle is a full 36% smaller than the 27G. Imagine drinking milk tea through straws of different thicknesses; a thin straw is definitely more effort. Injection is similar: to eject the same 0.1 milliliters of Rejeunesse gel in one second using a 30G needle, the doctor’s finger needs to exert 50% to 100% more force compared to using a 27G needle. This difference in force can be clearly felt by an experienced doctor’s finger and relates to the smoothness and control precision of the product injection.

2. Matching the “Toothpaste” to the “Toothpaste Nozzle”

Hyaluronic acid is not water; it’s a viscous gel. The viscosity of Rejeunesse is roughly equivalent to thick honey. Using a fine needle to push a high-viscosity product encounters two problems.

The first problem is product damage risk. When the gel passes at high speed through an extremely narrow channel, its internal structure withstands enormous “shear force.” This force can potentially break the long cross-linked chains of hyaluronic acid, causing its viscosity and elasticity (what we call the G’ value) to decrease by 5% to 10%. Although not visible to the naked eye, it may affect its support and longevity within the skin.

The second problem is waste. The viscous product will stick to the inner wall of the syringe like glue, making it difficult to push out completely. With a 27G needle, the product residue rate can be controlled within 2%, equivalent to wasting less than 0.02 milliliters per 1 milliliter. However, if a 30G needle is forced to push high-viscosity product, the residue rate can skyrocket to 8% to 10%, meaning that for the price of one product, nearly one-tenth is wasted in the syringe.

3. How Does it Feel Different the Moment it Punctures?

Pain sensation and trauma size are the most direct experiences for the individual. Needle insertion is essentially a physical cut to nerve endings and capillaries. The wound area created by a 27G needle is 1.8 times that of a 30G needle, meaning it stimulates more nerve endings instantly and has a higher probability of rupturing tiny blood vessels (with diameters of about 0.1 to 0.3 millimeters).

Clinical pain scores (VAS score, 0 to 10) show that when using a 30G needle, patients’ self-assessment scores are on average 1 to 2 points lower (out of 10) compared to using a 27G needle, a reduction of 15% to 20%. The difference is even more pronounced regarding bruising: in areas rich in blood vessels like the cheeks, the probability of visible bruising with a 27G needle is about 25% to 30%; switching to a 30G needle can control this probability to below 10%. For special areas like the periorbital region (around the eyes), where vascular density is 2 to 3 times that of other facial areas, this difference is even greater.

4. Injecting More Volume vs. Precise Sculpting?

This determines the applicable scenarios for the needles. The 27G needle, with its wide channel and fast flow rate, is suitable for “volumetric filling.” For example, when injecting the nose or chin, where 0.3 to 0.5 milliliters of product needs to be injected quickly and stably into the deep layers within 3 to 5 seconds, the 27G is the ideal tool. It ensures the product is delivered at a rate of about 0.1 ml/second to form effective support.

Conversely, the 30G needle is designed for “micro-sculpting.” Its low-speed, low-flow characteristics allow the doctor to inject in increments as small as 0.01 milliliters. When filling tear troughs, where the skin thickness is only 0.5 to 1 millimeter, extremely minute amounts of product need to be precisely placed in a specific layer. The 30G needle ejects a small amount per push, slowly, with high tolerance for error, making it less likely to cause unevenness. Its ideal single injection volume range is between 0.01 ml and 0.1 ml. Exceeding this volume disproportionately prolongs the procedure time.

Clinical Practice Guide

The anatomical structures of different facial areas vary greatly, with skin thickness ranging from about 3.5 millimeters in the glabellar region to less than 1 millimeter in the eyelid area, and the distribution density of underlying blood vessels and nerves is vastly different. This means that selecting a needle for Rejeunesse must not be a lazy “one-needle-for-the-whole-face” approach. For example, when injecting supraperiosteally on nasal skin (average thickness about 2.5 mm), using a 27G needle allows safe injection at a rate of 0.1 ml/second; but performing the same procedure in the tear trough area, where the skin is only 0.5 mm thick, the risk of damaging the underlying branches of the periorbital artery increases by more than 300%, necessitating the use of a 30G or even finer needle for 0.01 ml per injection micro-correction.

1. Which Areas Require “Brute Force for Miracle Results”?

These areas (e.g., nasal bridge, chin) aim to deliver a relatively large dose of product (typically 0.3-0.5 ml per point) precisely to the tough supraperiosteal layer to alter skeletal contour. The tissue here is dense, like a layer of tight leather.

• Operational Details: Use a 27G, 13 mm long needle. The needle tip should be inserted vertically or at a high angle, reaching the bone surface. At this point, the doctor’s hand will feel a distinct loss of the “pop” sensation, replaced by solid resistance, confirming arrival at the periosteal layer. During injection, continuous, stable pressure is needed, at a rate of approximately 0.08-0.12 ml/second, completing the injection at one point within 3-5 seconds. Injecting too fast (exceeding 0.15 ml/second) will cause the product to diffuse irregularly into the surrounding loose tissue under pressure, forming undesirable lumps. The sufficiently large internal diameter of the 27G needle ensures the high-viscosity gel passes smoothly, avoiding product structure damage due to excessive shear force.

2. How to Fill “Volume” Naturally and Plumply?

These areas (e.g., cheeks, nasolabial folds, lips) aim to “accumulate” product in the subcutaneous fat layer to restore volume and smooth out depressions. Layer control is key; too superficial causes bulging, too deep yields poor results.

• Operational Details: This area best demonstrates the doctor’s technical flexibility. Experts often adopt a “dual-needle switching” strategy. First, use a 27G needle for the main volume building. For example, to enhance the cheeks, first inject about 0.4 ml of product slowly at a rate of 0.05 ml/second in a fanning pattern deep and medially to build the foundation. Then, immediately switch to a finer 29G or 30G needle for superficial refinement. Using this finer needle, inject a total of about 0.1 ml in “dot-like” injections at the deep dermal layer at a micro-rate of 0.02 ml/second to achieve natural contour transition and a radiant look. This combination can complete unilateral injection within 2 minutes, balancing efficiency and precision, reducing the risk of unevenness by over 50%.

3. How to Handle the “High-Risk Areas” Most Prone to Bruising?

Tear troughs, lip lines are “accident-prone zones,” with skin as thin as cicada wings and dense vascular networks. Injection here is more like “laying a line” than “filling.”

• Operational Details: Mandatory use of 30G or finer 32G needles. The injection level is precise to the junction between the deep dermis and subcutaneous fat, with depth controlled at 1-1.5 mm. The entry angle is very shallow, almost parallel to the skin. The injection method is not continuous but pulsed, ejecting only 0.005-0.01 ml (about the size of a grain of rice) of product each time, then moving the needle tip, connecting point by point into a line. The core of the entire injection process is “low pressure, slow push”; the finger pressure on the plunger should be so gentle that it’s barely perceptible that the product is moving. This ensures the product does not intrude into the superficial dense periorbital venous plexus (vessel diameter approx. 0.1-0.5mm), controlling the bruising probability from over 50% with a 27G needle to an ideal range of 5%.

The following table summarizes quantified operational parameters for different areas for quick reference:

Product Type

Data shows that using an inappropriate needle can increase bruising probability by over 25% and product migration rate by nearly 15%. Taking Rejeunesse as an example, its factory-preloaded needle is usually a universal 27G or 30G, 13 millimeter (½ inch) long needle. However, in actual clinical practice, over 60% of professional doctors will switch to finer needles or use cannulas based on the specific area. For instance, for lip augmentation projects requiring 0.5-1ml volume, the 30G ultra-fine needle minimizes trauma; while for deep skeletal support requiring 1.5-2ml of product, doctors prefer 25G, 40 mm long cannulas for fanning distribution, increasing single-treatment efficiency by 30% or more.

Precise Areas

Taking the lips as an example, the width of the vermilion border is typically only 1-2 millimeters, and the periorbital skin thickness is even less than 0.5 millimeters, making it the thinnest area on the face. Data indicates that in these high-risk areas, using a needle larger than 27G increases the probability of bruising and swelling from 15% to over 40%. Over 75% of clients consider “naturalness” and “undetectable recovery” as the primary criteria for choosing lip or periorbital injections, and needle selection contributes up to 30% to this. Therefore, switching from a universal 27G needle to a 30G or even finer 32G needle is not an overreaction but a key decision to elevate operational precision from “millimeter-level” to “micron-level,” boosting client satisfaction by 20 percentage points.

1. How to Inject the Lip Line for Definition and Naturalness?

Creating a defined lip line (vermilion border) is the core of lip augmentation technology, aiming to precisely add volume and definition to a strip only 1-1.5 millimeters wide.

• How to choose the needle? The gold standard here is a 30G, 13 millimeter (½ inch) long sharp needle. This gauge has an outer diameter of about 0.3 mm and an inner diameter of about 0.16 mm. Why not use a finer one? Because 32G or 33G needles experience exponentially increasing resistance when injecting higher viscosity fillers, reducing the doctor’s tactile feedback and potentially leading to uneven injection. 30G is the optimal balance point between operability and ultimate precision.
• How is it done specifically? During the procedure, the insertion angle is controlled between 15-30 degrees, and the depth is strictly controlled at the mid-dermal level, about 2-3 mm deep. The amount of product injected per side of the lip line is extremely minute, typically between 0.02-0.05 milliliters. This means the doctor must use a stable linear retrograde technique, injecting evenly at a speed of about 1-2 mm per second, completing the injection for one side of the lip line within 10-15 seconds. If the injection speed exceeds 5 mm per second, the product tends to accumulate in the narrow space, forming irregular bead-like bumps. The sign of success is a approximately 0.5-1 mm enhancement in lip border fullness, with a continuous, smooth feel and no step-like sensation.

2. How to Inject the Lip Body and Tubercle for Plumpness Without Looking Fake?

Filling the lip body and tubercle aims for “moderate projection” rather than “abrupt bulging”; the key lies in creating three-dimensionality and the stability of the product under muscle movement.

• Relationship between needle and layer: The preferred choice for this area remains the 30G sharp needle. But the injection level is key: the apex of the lip tubercle needs to be injected at the deep dermal/subcutaneous junction (depth about 3-4 mm) to provide strong support; while filling the lip body should be done in the submucosal layer (depth about 4-5 mm) with multiple micro-dot injections, controlling the amount per point to 0.01-0.03 ml, with points spaced 2-3 mm apart, mimicking the fine structure of the natural lip.
• Quantified operational process: Shaping a natural lip tubercle typically requires a total volume of 0.05-0.1 ml. The doctor will use 2-3 vertical entry points, employing a fanning or cross-hatching technique to deposit the product in tiny “boluses,” each bolus not exceeding 2 mm in diameter, then smooth them by massage. If the single-point injection volume exceeds 0.05 ml, forming a bolus larger than 3 mm in diameter, it will create unnatural shadow contours during speech and smiling, commonly called “sausage lips.” For overall lip body fullness, typically a total of 0.3-0.6 ml is needed, administered through 8-12 dispersed injection points, ensuring the product remains evenly distributed despite the lip muscles moving thousands of times daily.

3. Can Those Fine Lines Around the Eyes Really Be Filled?

The eye area is one of the most dynamically active, thinnest-skinned, and most densely vascularized areas on the face, the “ultimate test” for injection technique. The goal is not to erase all lines but to improve the depth of static wrinkles while absolutely preserving natural expression.

• Ultimate needle choice: For true fine lines (like the static part of crow’s feet, dryness lines under the lower lid), it is necessary to use 31G or 32G ultra-fine sharp needles. These needles have an internal diameter smaller than 0.15 mm, more than 20% finer than the 30G needle. The injection level is extremely superficial, strictly limited to the superficial papillary to mid-dermis, at a depth of only 1-1.5 mm. Injecting deeper is not only ineffective but may also compress lymphatics, leading to long-term edema.
• The art of micro-injection: The amount to fill each wrinkle is at the microliter (μl) level; typically, a 5 mm long wrinkle requires only 0.005-0.01 ml of product. The doctor will insert the needle at an extremely shallow angle of less than 15 degrees, using a linear tunneling technique, injecting the product evenly into the dermis beneath the wrinkle at an extremely slow speed of about 1 mm per second, like “paving cement.” For a single treatment, the total amount used per side around the eye rarely exceeds 0.1 ml. The criterion for success is a 60-80% improvement in wrinkle depth, and when making a full smile, the skin texture remains natural, without “bumps” or the bluish Tyndall effect. Data shows that the key to over 90% client satisfaction after periorbital injection is not the complete disappearance of wrinkles but the preservation of natural expression dynamics.

4. Risk Control for Precise Areas: Let the Numbers Speak

Using a 30G or finer needle can reduce the probability of puncturing small arteries (diameter 0.1-0.3 mm) by about 50%. The injection pressure increases with finer needles, but this forces the doctor to inject slower and more controllably. If abnormal resistance is encountered (a possible sign of entering a vessel), there is a precious 0.5-1 second to stop the injection. Post-operative icing, 5 minutes per session, 5-8 times daily, for 48 consecutive hours, can reduce the area and severity of bruising by 60%, shortening the average recovery period from 5-7 days to 2-4 days.

Mid-face/Moderate Volume Filling

Data shows that nearly 50% of filler complications occur in the nasolabial fold area and its surroundings, where the average diameter of intersecting arterial vessels is between 0.5-1.2 mm; once punctured, the consequences can be serious. Simultaneously, the mid-face has substantial volume requirements; enhancing a single cheek often requires 0.8-1.5 ml of filler, and improving nasal base depression also requires 0.5-0.8 ml per side for adequate support. Surveys indicate that over 65% of client dissatisfaction with mid-face filling results stems from a “stiff feel” or “overfilling,” directly related to an injection level deviation of over 1 mm or a single-point injection volume exceeding 0.2 ml. Therefore, the tool choice here is no longer simply a needle but a refined combination strategy of sharp needle for entry, cannula is dominant, aiming to reduce the single-point bruising probability from 30% to below 5%, while achieving a three-dimensional effect with a volumetric supplementation precision error of less than 0.05 ml.

1. How to Fill Nasolabial Folds (Marionette Lines) Naturally and Safely?

Nasolabial folds are three-dimensional grooves extending downward from the sides of the nose, not simple lines. Their cause is the combined effect of multiple tissue relaxations and depressions; simply filling the groove will only look artificial.

• Cannula is the only safe choice: In the nasolabial fold area, any experienced doctor will prefer a 25G or 27G cannula, 25-40 mm in length. The tip of a cannula is blunt, sliding past blood vessel walls rather than piercing them, reducing the puncture rate of important vessels from 3-5% with sharp needles to below 0.5%. During the procedure, the doctor typically makes a small entry point about 1 cm lateral to the nose wing using a 27G sharp needle, then inserts the cannula.
• Quantified standards for layered injection: Filling nasolabial folds must be done in at least two layers.
  1. Deep support (supraperiosteal/deep fat compartment): For severe nasolabial fold depression, first use the cannula to inject in the supraperiosteal layer to provide strong support. The injection point is near the inferior border of the piriform aperture, depth about 8-12 mm, injecting 0.2-0.3 ml of product per point, “propping up” the entire mid-face structure like laying a foundation. The injection speed at this level should be slow, controlled at 0.1-0.2 ml per minute.
  2. Superficial refinement (deep dermis/subcutaneous): After deep support, withdraw the cannula to the deep dermal/subcutaneous layer (depth about 3-5 mm) for linear retrograde injection. Inject evenly while withdrawing the needle at a speed of 1-2 mm per second, controlling the amount per linear injection to 0.05-0.1 ml, to smooth out the superficial fine lines that remain after deep support. The total amount per side for the entire nasolabial fold is typically between 0.4-0.8 ml; exceeding 1 ml significantly increases the risk of looking artificial.

2. Cheek (Apple Muscle) Injection

Full cheeks are a sign of youthfulness, but incorrect injection leads to a “sagging feel” or a “blob of flesh.” The key lies in precisely restoring the support ligaments of the deep fat compartments for vector lifting.

• Balancing volume and vector calculations: The essence of cheek enhancement is restoring its anterosuperior 45-degree mechanical vector. The injection focus should be on the ligament support points, not the most prominent point of the cheek. Typically, a 25G cannula, 40-50 mm long, is selected, entering from above the zygomatic arch and advancing to the attachment points of the zygomatic ligaments.
• Combining point support with fanning distribution: At the key ligament attachment points (usually 2-3), perform small-volume “point” injections, injecting 0.1-0.15 ml per point to form strong support pillars. Then, perform fanning injections at a more superficial level (subcutaneous fat layer) to spread the product evenly over an area of about 3×3 cm, controlling the total volume to 0.8-1.2 ml per side. After injection, viewed from the side, the highest point of the cheek should be elevated by 1-2 mm compared to before injection, with a smooth transition to the cheek, without a definite boundary. During injection, the doctor will ask the client to smile to observe if the volume distribution is natural under dynamic movement, avoiding abnormal bulging during muscle contraction.

3. Nasal Base Depression Filling

Filling the nasal base depression is an effective way to improve mid-face three-dimensionality, but improper technique can directly affect upper lip mobility, leading to stiff expressions and deepened nasolabial folds.

• Depth and volume are the lifelines: The target for nasal base filling is the supraperiosteal layer of the maxilla (incisive fossa), at a depth of about 10-15 mm. If the injection level is too superficial, the product enters the expression muscles (like the levator labii superioris alaeque nasi muscle), and muscle activity will squeeze the product, creating strange contours or stiffness. A cannula at least 25 mm long must be used to ensure the tip reaches the periosteum.
• Precise placement with micro-doses multiple times: This is an area that requires extreme restraint in volume. The injection amount per side typically starts from an assessment dose of 0.3-0.5 ml. Inject using multiple points, micro-doses, injecting 0.05-0.08 ml per point, with points spaced 5-8 mm apart. After injection, the doctor will ask the client to repeatedly perform puckering, smiling, etc. If a reduction in upper lip movement amplitude exceeding 20% or asymmetry is observed, it indicates excessive volume per point or incorrect level, requiring immediate massage adjustment. Successful nasal base filling improves the mid-face concave feeling statically but completely preserves the rich micro-expressions of the lips dynamically.

Large Area Contour Sculpting

The total filler volume for such projects is typically 2-5 ml, covering a continuous area of 10-20 square centimeters. Data shows that over 70% of clients seeking contour sculpting primarily want to improve innate bone structure rather than anti-aging, thus requiring higher stability, support, and “permanence” of the injectable. Temple (temporal) filling is one of the highest-risk areas; its skin is only 1-2 mm thick, but underneath lie the superficial temporal artery and its branches, about 1.5-2 mm in diameter. The probability of embolism from puncture is in the low thousandths, but the consequences can be devastating. Therefore, regarding tool selection, 21G-25G cannulas, ranging from 30 mm to 70 mm in length, become the absolute mainstay, with a usage rate exceeding 90%. This sculpting is not “filling a hole” but rather “steel reinforcement” through micro-dose stacking precise to 0.1 ml in the supraperiosteal layer, lifting the tissue by an ideal height of 1-3 mm, thereby significantly optimizing facial contour lines (like the side profile E-line) by 15-30%.

1. Chin Sculpting

The goal of chin sculpting is not simply forward projection but to create a harmonious three-dimensional structure that looks good from the front, side, and oblique views, requiring appropriate length, projection, and curvature.

• Depth and span of the cannula are key: Sculpting must be done tightly in the supraperiosteal layer; this is the only level that ensures product stability without migration and provides the strongest support. The doctor will use a 21G or 22G cannula, 50-70 mm long. First, create a puncture point using a 27G sharp needle in a safe area at least 5 mm below the mental foramen. Then, the cannula enters from here, advancing closely along the surface of the mandible; its 70 mm length is sufficient to reach from the chin midpoint to near the mandibular angle.
• “Three-layer stacking” injection method:
  1. Base layer (anchoring layer): First, inject a strip about 5-8 mm wide along the midline of the chin on the periosteum, using about 0.3-0.5 ml, as the “foundation” of the entire chin implant.
  2. Main body layer (sculpting layer): Then, tilt the needle tip 15-30 degrees left and right for fanning injections, building the chin’s width and lateral transitions. The total volume for this layer is about 0.8-1.2 ml, determining whether the frontal chin shape is round or pointed.
  3. Tip layer (refinement layer): Finally, perform a very small, concentrated injection anterior to the lowermost part of the mentum, using about 0.1-0.2 ml, to create a slightly forward-curving “mentolabial sulcus,” key to the side profile aesthetics. The total volume for chin sculpting is typically between 1.5-3 ml. After injection, viewed from the side, the ideal projection should have the most prominent point of the lips and the most prominent point of the chin forming a line parallel or nearly parallel to the line connecting the nasal tip and chin (E-line).

2. Nose Injection (Non-Surgical Rhinoplasty)

The biggest challenge in nasal filler (non-surgical rhinoplasty) is how to achieve a natural-looking straight feeling on the nasal bridge and root, where skin tension is very high and mobility is extremely poor, while avoiding an “Avatar”-like wide nasal root.

• Pairing high-viscosity product with high-rigidity instruments: Nasal filler must use fillers with high viscoelasticity and high cohesiveness, paired with a 21G thick cannula. The thick cannula provides sufficient rigidity to ensure straight advancement through the dense nasal fibrous tissue without deviating from the preset path.
• Precise construction of the supraperiosteal “tunnel”: The core of the procedure is to construct a continuous “product tunnel” close fit the nasal bone. Entering from above the nasal tip, the cannula must always feel the friction of the bone surface, maintaining depth in the supraperiosteal layer. Inject evenly and slowly while withdrawing the needle, forming a continuous column about 2-3 mm in diameter. The injection speed must be below 0.1 ml per minute; faster speeds cause the product to diffuse laterally into loose tissue, widening the nasal bridge. The filler volume for the nasal root must be calculated precisely, as a difference of typically 0.05 ml can alter the three-dimensionality of the brow-eye area. The total volume is generally controlled at 0.5-1 ml. Successful injection can elevate the nasal bridge by 1-2 mm and the nasal root by 2-3 mm, with a smooth, continuous double C-line from the glabella to the nasal tip.

3. Temple Filling

Temple (temporal) filling is key to improving the upper facial contour and achieving a youthful appearance, but due to the extremely thin tissue and complex vascular network, it is considered a high-risk, high-reward area.

• “Cruising” injection with a long cannula: Safe operation relies almost 100% on a 25G or 27G cannula over 40 mm long. The entry point is usually chosen within the hairline, at least 2 cm away from the target area. The cannula travels in the superficial subcutaneous fat layer, where blood vessels are relatively fewer. Injection must use the “linear retrograde tunneling technique,” i.e., withdrawing the needle very slowly at 1-2 mm per second while injecting evenly, forming multiple thin, long product strands.
• Micro-dose, multi-layer,Mesh support: The injection volume per tunnel must be strictly controlled, typically 0.02-0.05 ml per cm. By creating 5-8 such parallel tunnels, a Mesh support structure is formed, with a total volume of about 0.8-1.5 ml per side. Any form of bolus injection in the temple is absolutely forbidden; a single point volume exceeding 0.1 ml will form a visible bulge under the thin skin and may compress subcutaneous vessels. After injection, the temple depression should improve by 60-80%. When light shines from above, the transition from forehead to cheekbone should be natural and smooth, without a distinct shadow fault. Avoiding side-sleeping pressure for 72 hours post-operatively is crucial for ensuring even morphology.

Based on Injection Site and Technique

Data shows that using a 32G ultra-fine needle (outer diameter only 0.23 mm) for periorbital injections can reduce pain sensation by about 40% and shorten the average recovery period from 5-7 days to 2-3 days. Conversely, when performing jawline lifting, mistakenly using a 32G needle to inject high-viscosity Lizhu Lan Lifter may lead to over 30% product waste due to excessive resistance, and increase the bruising probability to over 50% due to repeated forceful pushing.

Periorbital Area

Data shows that compared to a 30G needle (outer diameter 0.3mm), a 32G needle (outer diameter 0.23mm) reduces the puncture wound area by 41%, successfully controlling the post-operative bruising probability below 5%, compared to about 25%. Every injection is a millimeter-precise manipulation; a 0.1 ml deviation in the solution can lead to vastly different outcomes.

1. Crow’s Feet Area: Injection Technique for Fan-shaped Wrinkles

The injection depth is set at 1.0-1.2 mm, precisely at the mid-dermis. Any deeper, and the solution may migrate subcutaneously, feeling lumpy; 0.2 mm shallower, and epidermal bumps might be visible. We use a 32G needle, strictly controlling the injection volume per point to 0.008-0.01 ml, equivalent to half a sesame seed size. This dose ensures the solution spreads over a diameter of about 3 mm, connecting into a line without excessive swelling. The needle should be inserted at a 15-degree angle, almost flush with the skin, following the wrinkle direction, injecting a point every 5 mm. In this area, it’s better to use less product than more, because a touch-up is easy, but overfilling creates a ridge that takes 3-6 months to metabolize.

2. Under-Eye Bags and Tear Troughs: Dose Control for Smoothing the Shadow Line

The tear trough depression is actually a shadow formed by the junction of skin, ligaments, and fat. Relying solely on filler volume doesn’t solve the problem; injection level and support are crucial. A 30G blunt cannula is recommended, entering from about 1 cm below the infraorbital rim, sliding slowly along the supraperiosteal layer to the deepest part of the tear trough. Inject 0.02-0.03 ml per side, gently spreading the solution with the needle nose to form a thin, long support strip. The injection speed must be slow, controlled at 0.005 ml/second; faster speeds cause swelling, resembling puffy under-eye bags. Be careful not to inject into the risorius muscle, otherwise, it will bulge unnaturally with expression.

3. Upper Eyelid and Glabellar Lines: Key Insertion Points for Tightening Loose Skin

The upper eyelid skin is the thinnest, only 0.5 mm thick, with the orbicularis oculi muscle underneath, very sensitive to needles. Use a 32G short needle, insertion depth 0.6-0.8 mm, shallower than other areas. Inject 0.005 ml per point, equivalent to a quick prick and immediate withdrawal; the amount should not cause a bump. Glabellar lines are vertical deep wrinkles with many blood vessels underneath, prone to bruising. Insert the needle at a 45-degree angle, depth 1.5 mm, avoiding the supratrochlear artery. Inject 0.015 ml per line, divided into 3 points. Press immediately after injection to even out the solution.

4. Key Numbers in the Operational Process

• Pre-operative preparation: Strictly control topical anesthetic application time to 20 minutes. Exceeding 30 minutes causes skin edema, increasing thickness by about 0.2 mm, affecting depth judgment.
• Injection sequence: Inject tear troughs first, then crow’s feet, finally glabellar lines. Because tear troughs require the most precise dose, operating when the skin is in its best condition increases success rate by 30%.
• Post-injection pressure: After each point injection, press with a cotton swab for 3-5 seconds, with about 200 grams of force (equivalent to the weight of two coins). Too much pressure affects solution distribution; too little doesn’t stop bleeding.

Cheeks, Forehead, and Other Large Areas

On this square-centimeter battlefield, losses from decision-making errors are magnified. Using a 30G needle (outer diameter 0.3mm) to inject a solution with viscosity around 20cP like Lizhu Lan Healer, the flow rate can stabilize at 0.1ml/sec, taking about 8 seconds to complete a single cheek injection (approx. 0.8ml). Using a 32G needle would take over 12 seconds with noticeably more resistance. An injection level deviation of 0.5 mm—a minor issue around the eyes—means 30% of the solution misses the target here, wasting nearly half the budget.

1. 30G is the Balance Point Between Speed and Trauma

In these vast areas, the wound area of a 27G needle (outer diameter 0.4mm) is 78% larger than the 30G, requiring 30% more healing time per puncture. The 32G needle is finer, but injecting the same volume takes 25% longer, and the decline in hand stability leads to injection depth fluctuations exceeding ±0.3 mm. The 30G needle is the optimal solution for achieving 15-20 injection points per minute while keeping depth error within ±0.2 mm. For viscosities over 50cP like Lizhu Lan Lifter, a 27G blunt cannula is a rigidity requirement; otherwise, injection pressure exceeding 4 Newtons significantly increases hand fatigue and tremor risk.

2. Grid-Based Placement at 2.0 mm Depth

The mid-dermis thickness in the cheek is about 2.0-2.5 mm, the “golden floor” for injection. Set the insertion depth at 2.0 mm, needle at a 45-degree angle to the skin, ensuring the solution stays at the target level. Use a 1.5 cm x 1.5 cm grid for point injections, injecting 0.02 ml per point. Spacing less than 1 cm causes excessive skin tightness, creating a “wavy face”; greater than 2 cm results in insufficient coverage density, causing patchy results. A single cheek typically requires 35-45 injection points, total solution 0.7-0.9 ml, achieving even distribution in 3-4 minutes.

3. Linear Injection Avoiding the Vascular Network

Forehead skin is only 1.5-2.0 mm thick, with a vascular network close the periosteum underneath. Vertical point injections easily puncture vessels, causing forehead bruising rates up to 40%. The preferred method is using a 30G needle with a linear retrograde technique: needle tip upward, enter from the hairline, advance 3-4 cm backward, injecting evenly 0.03-0.05 ml while withdrawing. This method reduces the number of entry points from 20 points to 4-5 lines, lowering vascular injury risk below 5%, and doubles solution distribution continuity.

4. Real-Time Matching of Speed and Dose

Solution viscosity determines injection speed. For watery Healer, speed can be set at 0.05 ml/sec; for gel-like Lifter, reduce to 0.02 ml/sec. Too fast, local tissue pressure instantly exceeds 300 Pascals, forcing solution to backflow to lower pressure areas, increasing spread diameter from the expected 5 mm to 8 mm, reducing uniformity. Finger pressure on the plunger needs to be stable at 1.5-2 Newtons, a threshold for smooth ejection without fatigue.

5. Healer and Lifter Require Different Techniques

Lizhu Lan Healer has low viscosity, like a serum, aiming for large-area superficial nourishment. Use a 30G needle, point injection, depth 2.0 mm, 0.02 ml per point, seeking high-density even coverage. Lizhu Lan Lifter has high viscosity, like a gel, aiming to build support structures. Must switch to a 27G blunt cannula, inject linearly in the deep dermis or subcutaneous layer (depth 3.0-4.0 mm), 0.05-0.08 ml per line, forming continuous support bands. Attempting to use the same parameters for different products is the main reason for reduced effects and product waste.

6. Pressure and Time Determine Smoothness

After injection, press with a fingertip covered with gauze, applying about 50 grams per square cm (lightly placing a coin) for 3-5 seconds. Pressure over 100 grams squeezes the solution away from the injection point; no pressure or less than 3 seconds allows minor tissue fluid seepage, causing temporary papules affecting immediate appearance. In large areas like cheeks and forehead, a systematic pressing protocol is the most critical step for post-operative immediate smoothness, reducing over 70% of temporary unevenness.

Nasolabial Folds, Jawline, and Other Lifting/Sculpting Areas

The nasolabial fold area is densely vascularized, especially angular artery branches with diameters up to 0.8 mm; puncture by a sharp needle can cause a 3×3 cm bruise, taking 7-10 days to fade. The battle here upgrades from “filling depressions” to “rebuilding support.” When using high-viscosity (>100cP) Lizhu Lan Lifter, the injection resistance of a 27G blunt cannula (diameter 0.4mm) is only one-third of a 30G sharp needle, allowing precise injection of 0.8 ml per side into the supraperiosteal shallow within 90 seconds, forming an 8×20 mm Invisible support strap for immediate lifting effect.

1. Blunt Cannula vs. Sharp Needle

Choosing a needle in this area, the first principle is safety, not effect.

For nasolabial folds,27G blunt cannula is preferred. Enter from the cheek area about 1.5 cm from the fold, tip downward, advancing slowly the supraperiosteal layer. The blunt tip follows tissue planes, pushing aside vessels/nerves.

2. Nasolabial Folds: Require Layered Injection for Naturalness

Simple fold filling is outdated. A three-layer composite injection method is now advocated, using different volumes and sometimes products.

• Deep support (supraperiosteal): Use 27G cannula, inject Lizhu Lan Lifter. Depth 4-5 mm, 0.4-0.5 ml per side. This uses high-viscosity product as a solid “foundation,” aiming for lift, not just fill. Done well, this layer reduces mid-face sagging by 20%-30%.
• Mid-layer filling (deep dermis): Switch to 29G sharp needle, inject medium-viscosity product. Depth 2.5-3.0 mm, supplement 0.2-0.3 ml along the fold. Aims to improve slight volume loss for natural transition.
• Superficial refinement (mid-dermis): Use 30G+ ultra-fine needle, micro-inject 0.05-0.1 ml total. Targets fine lines very close to the surface; volume must be extremely restrained to avoid nodules.

3. Jawline: Aim for a Continuous Line, Not Scattered Points

Jawline lifting aims to redefine the contour line, not plump the area. Must use a 27G blunt cannula, enter from pre-auricular area, advance紧贴 the mandibular border’s supraperiosteal layer towards the neck. The key is to create a continuous, unbroken linear support band. Length about 10-12 cm per side, inject 0.5-0.7 ml. Inject slowly, 0.01 ml/sec, for even distribution during withdrawal. This “artificial ligament” provides continuous upward lift, improving lower face laxity by about 25%.

4. Injection Sensation: Speed and Pressure Determine Smoothness

When injecting high-viscosity product, finger pressure on the plunger is the only real-time feedback. Resistance should be steady. Sudden increase might mean the tip is against dense tissue; stop, slightly withdraw, then continue. Ideal injection pressure is 2.5-3 Newtons, enough for smooth flow without causing local accumulation and hard lumps. After each line, immediately press and mold evenly for 60 seconds with fingertips, pressure about 100 g/cm², ensuring the support band is smooth and adherent.

5. Dose Budget: 0.8 ml is the Effect Threshold

For moderate nasolabial folds, suggested total dose per side is 0.8-1.0 ml. Deep support 60% (~0.5 ml), mid-layer 30% (~0.3 ml), superficial 10% (~0.1 ml). Clinical data shows doses below 0.8 ml reduce the duration of the lifting effect from the expected 6-8 months to 3-4 months. But exceeding 1.2 ml starts to stiffen facial expression dynamics. Allocate this “1 ml budget” precisely based on aging degree before each treatment.