Background <p>Poly-D,L-lactic acid (PDLLA) skin boosters are widely used for biostimulatory skin rejuvenation, but comparative data on pain perception between injection techniques remain limited.</p> Objective <p>To compare patient-reported pain between intradermal and subdermal PDLLA injections using a randomized, double-blinded, split-injection design.</p> Methods <p>Twenty-one healthy participants (aged 27–64) each received ten facial injections: five intradermal and five subdermal, administered in randomized order using a 32G needle. Pain was assessed using a Visual Analogue Scale (VAS) immediately after each injection. The primary outcome was the difference in mean VAS scores between techniques. Secondary analyses examined the effects of age and gender on pain perception.</p> Results <p>The mean VAS score for intradermal injections was significantly higher than for subdermal injections (6.18 vs. 3.85, p&lt;0.001). No significant gender-based differences were observed. Patients under 40 reported higher intradermal pain than older subjects (p=0.04), but age had no impact on subdermal pain.</p> Conclusion <p>Subdermal PDLLA injections are significantly less painful than intradermal injections, likely due to lower nerve density and reduced dermal resistance. With equivalent efficacy and minimal downtime, subdermal injection may be preferable for patient comfort and compliance.</p> Level of Evidence V <p>This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors<a href="http://www.springer.com/00266">www.springer.com/00266</a></p>