yes i take peptides · shopping companion

LL-37

Cathelicidin

Category · For RecoveryStatus · RUOCitations · 60

The verdict

Mostly no — the autoimmune-amplification concern is real and not theoretical.

By source — cost, legality, risk

Brand
Not available
None — no FDA approval
No FDA-approved LL-37 exists.
Compounded 503A pharmacy
$140–$300/mo
Rx · off-label systemic use (topical-only evidence)
Mid. Some compounders carry; legitimacy depends on whether prescriber documents an indication.
RUO research peptide
$45–$120/mo
Sold 'for research only'
Highest. LL-37 is long (37 residues), synthesis quality varies — sub-90% purity is common.
Gray-market raw
~$6/mo (amortized — one box covers many months)
Unregulated overseas import
Crypto/Wise pay, no published COA; synthesis-difficulty of the 37-residue parent means identity-failures are common at the cheapest tier.

Stop signals · abort if

Stop and evaluate for: new joint pain or swelling
new rash, especially photosensitive
new oral ulcers
persistent low-grade fevers
new fatigue out of proportion
any pattern that looks like an autoimmune flare. Persistent infection or worsening

Sources · top 5 of 60

01Segreto F, et al. Cathelicidin LL-37 Expression in Human Breast Implant Capsules. Plastic and reconstructive surgery. 2024;153(5):1066-1073. PMID: 37220260.
02Leite ML, et al. The LL-37 domain: A clue to cathelicidin immunomodulatory response?. Peptides. 2023;165:171011. PMID: 37068711.
03Memariani H, et al. Antibiofilm properties of cathelicidin LL-37: an in-depth review. World journal of microbiology & biotechnology. 2023;39(4):99. PMID: 36781570.
04Wnorowska U, et al. Nanoantibiotics containing membrane-active human cathelicidin LL-37 or synthetic ceragenins attached to the surface of magnetic nanoparticles as novel and innovative therapeutic tools: current status and potential future applications. Journal of nanobiotechnology. 2020;18(1):3. PMID: 31898542.
05Memariani M, et al. Antifungal properties of cathelicidin LL-37: current knowledge and future research directions. World journal of microbiology & biotechnology. 2023;40(1):34. PMID: 38057654.