Peptide Knowledge Base · Immune
LL-37: what it is, what the evidence says, and its real status
A natural cathelicidin antimicrobial and immune-signaling peptide, restricted, and pro-inflammatory in the wrong context.
Short version: 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: Restricted · research-only · Education only.
Not available. LL-37 is a research-only antimicrobial peptide, restricted on the FDA Tracker and not FDA-approved. Education only; it can be pro-inflammatory and is not characterized for safe human use.
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 — preclinical; dual antimicrobial / pro-inflammatory biology. 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.
How it is taken
Not offered; education only.
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 or the knowledge base.
Last reviewed 2026-08-11 · Peptós.LIFE · Not medical advice.