Topical Anesthesia for Scalp PRP Treatment
Use pharmaceutical-grade topical numbing cream containing lidocaine-prilocaine (such as EMLA or generic equivalents) applied under occlusion for 45-60 minutes prior to PRP scalp injections. 1
Guideline-Based Recommendation
The Indian Association of Dermatologists task force, after evaluating 30 articles on PRP for androgenetic alopecia, specifically recommends that topically applied pharmaceutical grade numbing cream is highly recommended for scalp PRP injections. 1 This recommendation acknowledges that PRP therapy is generally associated with pain upon injection, particularly given the multiple point injections required (spaced 1 cm apart across treatment areas). 1
Optimal Topical Anesthetic Choice
Lidocaine-Prilocaine Combinations (EMLA or Generic)
- EMLA cream (2.5% lidocaine/2.5% prilocaine) is the most studied and effective topical anesthetic for needle-based procedures, demonstrating significantly greater pain relief than placebo and equivalent efficacy to lidocaine infiltration. 2
- Minimum application time is 45 minutes under occlusive dressing to achieve adequate dermal anesthesia. 3
- Optimal application time is 52-60 minutes for maximal effect before needle procedures. 4, 5
- Generic 2.5% lidocaine/2.5% prilocaine preparations show high absorption rates (0.72 µg/mL serum levels), providing effective anesthesia. 5
Alternative Options (Less Preferred)
- 4% lidocaine preparations (LMX-4, Topicaine) are available over-the-counter but show unpredictable absorption with higher systemic levels (0.44-0.808 µg/mL), increasing risk of adverse reactions. 5
- Ice application (1-2 minutes) provides inferior but clinically acceptable pain control compared to EMLA, with advantages of immediate availability and low cost. 4
Clinical Application Protocol
Pre-Treatment Preparation
- Instruct patients to shampoo and detangle hair before the session with no styling products (wax, gel, hairspray). 1
- Comb through and mark treatment areas before anesthetic application. 1
Anesthetic Application Technique
- Apply pharmaceutical-grade lidocaine-prilocaine cream to mapped scalp treatment areas. 1
- Cover with occlusive dressing for 45-60 minutes. 4, 3
- Use high-quality 30G × 4mm needles for injection to minimize additional discomfort. 1
Important Safety Considerations
Systemic Absorption Risks
- Significant interindividual variation exists in lidocaine absorption and metabolism, even with standardized application. 5
- Over-the-counter preparations should be used under healthcare professional supervision to avoid toxic effects. 5
- Contraindicated in infants under 6 months due to methaemoglobinaemia risk from prilocaine metabolites. 2
Patient-Specific Factors
- Monitor for adverse reactions including transient skin blanching, erythema, and rare cases of postinflammatory hyperpigmentation. 5, 2
- Consider lower concentrations or shorter application times in patients at extremes of age or body mass index. 6
Common Pitfalls to Avoid
- Insufficient application time (less than 45 minutes) results in inadequate anesthesia. 3
- Failure to use occlusive dressing reduces drug penetration and efficacy. 4, 3
- Using ice alone as primary anesthetic provides suboptimal pain control compared to pharmaceutical preparations. 4
- Applying topical anesthetic without healthcare supervision increases risk of systemic toxicity in susceptible individuals. 5