Peptide Knowledge Base · Immune

LL-37: what it is, what the evidence says, and its real status

A host-defense peptide with real antimicrobial biology, but it can also drive inflammation, and it is restricted. On the Tracker, not the shelf.

Can you actually get it?

Plain-English verdict: Education only.

Regulatory status: Expected to stay restricted.

How does LL-37 work?

A cathelicidin-family peptide that disrupts microbial membranes and modulates innate immune signaling, sometimes pro-inflammatory.

What it does — and what it does not do

What it does: Studied for antimicrobial and immune-modulating activity.

What it does not do: It is not approved or available, and its pro-inflammatory potential is a real caution.

How honest is the evidence?

Evidence grade D — Animal and lab evidence; human trials still to come.

preclinical; dual antimicrobial / pro-inflammatory biology

A grade measures how much human evidence exists, not whether a molecule is good, safe, or worth your interest. Read our grading methodology for what each grade means.

What we still don't know: The line between immune support and harmful inflammation is poorly characterized; no human dosing.

WADA status: Not prohibited.

Who should not take it

Pro-inflammatory potential; not characterized for safe human use.

Sources

Cathelicidin / LL-37 host-defense literature; FDA compounding restriction list

Compounded medications are not FDA-approved. We keep two signals separate and never collapse them: whether you can get something, and what the rule currently says. See the live FDA Peptide Tracker for status.

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Last reviewed Jun 18, 2026 · Peptós.LIFE · Not medical advice.