LL-37vsP21
LL-37 vs P21 — independent comparison of uses, administration, pricing across providers, and key differences. Last reviewed April 21, 2026.
Quick Verdict
Based on clinical evidence and real patient data
The only known human cathelicidin antimicrobial peptide, naturally produced by immune cells and epithelial tissues. LL-37 has broad-spectrum antimicrobial activity alongside potent immunomodulatory and wound-healing properties.
A 21-amino-acid peptide that mimics the action of ciliary neurotrophic factor (CNTF). Studied for neurogenesis, cognitive improvement, and neuroprotection. Shows promise in animal models for enhancing memory consolidation and protecting against neurodegenerative decline.
Best choice depends on your insurance, budget, and treatment history.Take the quiz to get a personalized recommendation.
LL-37 vs P21: At a Glance
Full comparison across all key factors.
| Factor | LL-37 | P21 |
|---|---|---|
| Category | recovery | cognitive |
| Also Known As | Cathelicidin, hCAP18/LL-37 | CNTF analog, Colostrinin fragment |
| Administration | Topical or subcutaneous injection | Intranasal spray |
| Prescription | Required | Required |
| Providers | 3 providers | 3 providers |
| Common Uses |
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Data sourced from FDA prescribing information and peer-reviewed clinical trials. Prices reflect telehealth platform costs as of April 21, 2026. See our methodology.
Pricing by Provider
3 providers offer both LL-37 and P21.
| Provider | LL-37 | P21 | Consultation | Lab Testing |
|---|---|---|---|---|
 | $50/one-time | $55/one-time | Async Telehealth | No |
 | $180/monthly | $180/monthly | Video Telehealth | Yes |
 | $240/monthly | $230/monthly | Video Telehealth | Yes |
Key Differences
LL-37
The only known human cathelicidin antimicrobial peptide, naturally produced by immune cells and epithelial tissues. LL-37 has broad-spectrum antimicrobial activity alongside potent immunomodulatory and wound-healing properties.
P21
A 21-amino-acid peptide that mimics the action of ciliary neurotrophic factor (CNTF). Studied for neurogenesis, cognitive improvement, and neuroprotection. Shows promise in animal models for enhancing memory consolidation and protecting against neurodegenerative decline.
Which Is Right for You?
Choose LL-37if…
- You want a recovery medication
- You prefer topical or subcutaneous injection administration
- 3 providers available on our platform
- Your primary goal is antimicrobial defense
- Your primary goal is chronic wound healing
Choose P21if…
- You want a cognitive medication
- You prefer intranasal spray administration
- 3 providers available on our platform
- Your primary goal is neurogenesis
- Your primary goal is memory consolidation
Frequently Asked Questions
What is the difference between LL-37 and P21?
Which is cheaper, LL-37 or P21?
Can I switch from LL-37 to P21?
Medical Disclaimer
This comparison is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before starting, stopping, or changing any medication. Individual results may vary. The information presented reflects publicly available data and may not account for your specific health situation.