Peptide Academy · Recovery

LL-37

Also known as Human cathelicidin

Educational research summary, not medical advice. Many compounds here are not approved for human use. Talk to a licensed clinician before making any health decision.

The Peptide Academy is free to read. Members also get the research protocols for LL-37, dose and vial tracking, and an AI Advisor with cited sources. Try it all free for 7 days, no card needed.

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What is LL-37?

The body's only cathelicidin antimicrobial peptide, studied for infection defense and immune modulation.

How it works

Disrupts microbial membranes and modulates innate immunity via FPRL1, EGFR and TLR pathways; also promotes angiogenesis and wound closure.

What it has been studied for

Broad-spectrum antimicrobial activity
Antiviral defense
Wound healing support
Innate immune modulation
Anti-biofilm activity

These are effects reported or investigated in research, much of it preclinical. They are not proven outcomes or health claims.

Published research

Extensive in-vitro antimicrobial and biofilm data
Small human work in chronic wounds and atopic dermatitis

Half-life

Short — minutes to hours (antimicrobial peptide)

Cautions

Pro-inflammatory at high doses; implicated in psoriasis pathophysiology. Unapproved.

Side effects & fixes

Common side effects

—Pain, redness and swelling at the injection site
—Itching

Histamine reactions

Common. LL-37 directly triggers mast cells to release histamine, so pronounced local redness, itching and welts are expected.

Common fixes

Rotate injection sites (abdomen, thighs, upper arms) and stay at least an inch from the last spot.
Let the alcohol swab dry fully, let the solution reach room temperature, and inject slowly with a fresh needle.
A cold compress for 5–10 minutes eases a red or itchy welt; it should fade within a day.
For mild itching, redness or flushing, a non-drowsy over-the-counter antihistamine (such as cetirizine or loratadine) is commonly used — check with a pharmacist first, especially if you take other medicines.
Use the most dilute practical solution and the lowest dose.

Stop and get help

Reactions that spread beyond the site or last more than a day.
Stop and get emergency help for swelling of the face, lips, tongue or throat, trouble breathing, widespread hives, chest pain or fainting.

Basis: Mechanism studies and limited human data. Educational only, not medical advice.

Medication concerns

Theoretical: no human interaction studies

Immunosuppressants (transplant drugs like tacrolimus, high-dose steroids, biologics for autoimmune disease)
This compound is meant to stimulate the immune system, which may work against these medicines. Talk to the prescribing specialist first.
Antibiotics
Not studied together. Don't use LL-37 in place of prescribed antibiotics for an infection.
Everything else you take, including supplements
Bring a full list of medicines and supplements to your pharmacist or clinician before starting.

Basis: No human interaction studies; concerns follow from antimicrobial and immune effects. Educational only, not medical advice. Never stop or change a prescribed medicine without your prescriber.

Protocols & tracking are members-only

Members see the research protocols for LL-37, plan schedules, track every dose and vial, and ask the AI Advisor questions with cited sources. Try every Researcher feature free for 7 days, no card needed.

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