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FDA Category 2 · restricted from compounding

This compound is on the FDA’s interim Section 503A Category 2 bulks list and cannot be legally compounded by US pharmacies. An HHS announcement in February 2026 signaled intent to restore several peptides to Category 1, but no Federal Register action has been published. Check the FDA PCAC schedule for updates.

Read the full regulatory context
ClinicalImmuneTopicalPartial data

LL-37 (Cathelicidin)

hCAP18 · LL37

Endogenous 37-aa cationic antimicrobial peptide with immunomodulatory, wound healing, and angiogenic effects.

§ 01   Overview

Overview

Endogenous 37-aa cationic antimicrobial peptide with immunomodulatory, wound healing, and angiogenic effects.

Grönberg 2014 chronic leg ulcer trial; multiple engineered analogs in trials.

§ 02   Mechanism

Mechanism of action

LL-37 is the active form of the human cathelicidin hCAP18. It directly disrupts microbial membranes, modulates innate immune responses, and promotes wound healing and angiogenesis. Engineered analogs (OP-145, omiganan) are in clinical development.

  • 01Direct antimicrobial activity
  • 02Immunomodulation
  • 03Studied in chronic leg ulcers and COVID-19

§ 03   Dosing

Dosing protocol

Standard Protocol

Dose Range
Topical / trial-dependent
Route
Topical

§ 04   Evidence

Evidence & research

Clinical

Grönberg 2014 chronic leg ulcer trial; multiple engineered analogs in trials.

FDA Status

Not FDA-approved as a drug. Engineered analogs in clinical trials.

§ 06   News

In the news

5 articles from the last 12 months · updates hourly

§ 07   Sourcing

Sourcing & supply

Regulatory status

Restricted from compounding

Placed on the FDA's 503A Category 2 list and cannot be lawfully compounded in the US. No brand pharmacy alternative exists. US buyers encounter only research-use-only (RUO) channels, which the FDA's Intended Use Doctrine treats as unapproved drug sales.

No suppliers in our directory currently stock this compound. For investigational or research-only compounds, legitimate channels may not exist outside clinical trials.

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§ 09   Safety

Safety & side effects

Side effects

  • 01Local irritation
  • 02Potential pro-inflammatory at high doses

Contraindications

None specified.

§ 10   Questions

LL-37 (Cathelicidin) FAQ

What is LL-37 (Cathelicidin)?
Endogenous 37-aa cationic antimicrobial peptide with immunomodulatory, wound healing, and angiogenic effects. LL-37 is the active form of the human cathelicidin hCAP18. It directly disrupts microbial membranes, modulates innate immune responses, and promotes wound healing and angiogenesis. Engineered analogs (OP-145, omiganan) are in clinical development.
What is LL-37 (Cathelicidin) used for?
Reported uses include direct antimicrobial activity, immunomodulation, and studied in chronic leg ulcers and covid-19. Evidence strength is rated Clinical — see the evidence section for detail.
How is LL-37 (Cathelicidin) dosed?
Commonly referenced dosing is Topical / trial-dependent, administered Topical. This is educational reference only; consult a licensed clinician before use.
What are the side effects of LL-37 (Cathelicidin)?
Commonly reported side effects include local irritation and potential pro-inflammatory at high doses. This list is not exhaustive.
Is LL-37 (Cathelicidin) legal?
Placed on the FDA's 503A Category 2 list and cannot be lawfully compounded in the US. No brand pharmacy alternative exists. US buyers encounter only research-use-only (RUO) channels, which the FDA's Intended Use Doctrine treats as unapproved drug sales. FDA status: Not FDA-approved as a drug. Engineered analogs in clinical trials..

§ 11   References

Selected references

  1. 01

    Grönberg — chronic leg ulcers

    PMID: 22025658 (NCT02526030)

  2. 02

    COVID review

    PMID: 32225038

This site is for educational and research purposes only. It does not constitute medical advice. Always consult a qualified healthcare provider before using any peptide or supplement.