One of our partner clinics in London runs a split-face study every quarter on a volunteer patient. They compare two protocol variables side by side — depth versus pass count, serum versus no serum, stamp versus drag technique. Over three years they have accumulated data that tells a different story than the device manuals. We share the relevant findings here.
We track needle depth recommendations across 12 indications based on our partner clinics’ treatment logs. Here is what the data shows.
First, the relationship between needle depth and clinical outcome is not linear. Most clinicians assume deeper penetration means better results. Our partner clinic data shows an optimal depth window for each indication, and exceeding that window does not improve outcomes — it only increases downtime and complication risk.
Second, the effect of topical numbing on effective needle depth is underestimated. Patients who have applied numbing cream under occlusion for 45 minutes or longer develop significant tissue edema. This artificially increases skin thickness by up to 30%. If you set your needle depth based on the manual without accounting for this, you will penetrate deeper than intended once the edema subsides.
Third, the entry angle relative to the skin surface matters. At a 90-degree perpendicular angle, the full needle length penetrates. At 45 degrees, the effective depth is roughly 70% of the needle length. This is useful for areas with thin skin, but only if the practitioner understands the geometry.
For Fitzpatrick I-III skin, we recommend starting at 0.5mm for superficial indications and increasing in 0.25mm increments based on clinical response. For Fitzpatrick IV-VI skin, cap the depth at 1.0mm for the first session and observe healing response before increasing. The risk of PIH in darker skin types increases sharply above 1.0mm in our partner clinics’ experience.
We compiled these recommendations from the treatment data shared with tbphp by our partner clinic network — real numbers from real cases.
Clinical microneedling is still evolving. The clinics that get the best outcomes are the ones that track their data and adjust their protocols based on evidence rather than habit. The equipment and consumables matter, but technique and protocol consistency matter more.
Further Reading
About Skincare Protocol
Skincare Protocol is a clinical reference resource for aesthetic professionals. We document microneedling treatment protocols, post-care guidelines, and device selection criteria based on published research and practitioner experience. Content is aimed at clinic owners, aestheticians, and skincare professionals refining their treatment protocols. The cartridges referenced in these protocols are manufactured by tbphp.