Overview

The body's own broad-spectrum antimicrobial peptide, and a good illustration of why "natural" does not mean "safe to add more of". LL-37 is also directly implicated in the pathology of psoriasis, rosacea and lupus.

Not approved for human use anywhereNo approval anywhere for human use. Sold under research-use labelling. Not approved for human use.

At a glance

Regulatory status	Not approved. Studied topically for chronic wounds; systemic use unstudied. Has a genuine pro-inflammatory disease association.
Drug class	Human cathelicidin antimicrobial peptide — 37 residues
Route	Topical or subcutaneous (research)
Half-life	Short; rapidly degraded
Evidence rating	2/5 Limited Evidence rating 2 out of 5: Limited Preclinical work plus scattered human reports, uncontrolled use, or negative trials.
Studied in	Small phase 1/2 topical trials in hard-to-heal venous leg ulcers; extensive immunology research; substantial literature on its role in autoimmune skin disease.

How it works

Amphipathic helical peptide that disrupts bacterial membranes and neutralises endotoxin. It also acts as an immune signalling molecule, chemoattracting neutrophils and monocytes, and — critically — forms complexes with self-DNA and RNA that activate plasmacytoid dendritic cells, driving interferon responses.

Evidence base

Rated 2 of 5 — Limited. Preclinical work plus scattered human reports, uncontrolled use, or negative trials.

One of the clearest examples of a peptide whose known biology argues against casual use.

Benefits & potential uses

Bars indicate how well each claim is supported: three = strong human evidence, two = moderate, one = preliminary or preclinical.

Broad-spectrum antimicrobial activity Moderate evidence

Active against bacteria, fungi and some viruses, including biofilm-forming organisms, with a membrane mechanism that resists conventional resistance development.
Chronic wound healing signal Preliminary

A small randomized topical trial in venous leg ulcers showed improved healing rates.
Endotoxin neutralisation Preliminary

Binds and neutralises bacterial LPS in laboratory models.
Immune cell recruitment Preliminary

Chemotactic for neutrophils, monocytes and T cells.

Risks, cons & cautions

Bars indicate seriousness: three = serious or common, two = moderate, one = minor.

Drives autoimmune skin disease Serious

LL-37 is overexpressed in psoriasis and rosacea lesions and functions as an autoantigen in psoriasis. Adding more is mechanistically the wrong direction in these conditions.
Pro-inflammatory at higher concentrations Serious

The same peptide is antimicrobial at low concentration and inflammatory at high concentration — a narrow therapeutic window.
Cytotoxic to human cells at higher doses Moderate evidence

Membrane-disrupting activity is not perfectly selective for microbes.
No systemic human data Serious

Injectable use has never been evaluated.
Lupus association Serious

LL-37-DNA complexes are implicated in systemic lupus erythematosus pathogenesis.

Who should avoid it

Psoriasis, rosacea, or lupus
Any autoimmune inflammatory condition
Pregnancy
Systemic use generally

If used under medical supervision, monitor

No validated monitoring exists

Commonly confused with

These mix-ups cause real harm — two products sold under one name, or two molecules whose effects run in opposite directions.

KPV Research Use Only Evidence 1/5

Both host-derived peptides sold for inflammation, with opposite immune directions. KPV suppresses NF-kB signalling; LL-37 is pro-inflammatory at higher concentrations and drives psoriasis and lupus pathology.

Compare side by side

Regulatory & legal status

Not approved for human use.

Infographic

LL-37 — benefits & risks at a glance Download SVG

Where to read further

We link to live literature searches rather than a frozen citation list, so you always see current results — including anything published after our last review.

antimicrobialwound healinginflammationhigh risk

Related peptides in Antimicrobial & Antibiotic

Terms used on this page

Antimicrobial Peptide (AMP): Antimicrobial peptides are short cationic amphipathic sequences of innate immunity that kill microbes mainly by disrupting anionic membranes, a mechanism far easier to demonstrate than to develop into a drug.
Amphipathicity: Amphipathicity is the segregation of hydrophobic and hydrophilic residues onto opposite faces of a folded peptide, the arrangement that lets a sequence sit in and disrupt membranes.
Interferon: Interferons are antiviral and immunoregulatory cytokines, grouped into type I, type II and type III families, that signal through JAK-STAT to switch on hundreds of interferon-stimulated genes.
Endotoxin (Lipopolysaccharide): Endotoxin is the lipopolysaccharide of Gram-negative outer membranes, a heat-stable TLR4 agonist that causes fever and shock at nanogram doses and that sterilisation does not remove.
T Cell: T cells are the lymphocytes of adaptive cellular immunity, each carrying a uniquely rearranged receptor that recognises a peptide fragment only when it is displayed by an MHC molecule.
Therapeutic Window: The therapeutic window is the range of exposure above the concentration needed for effect and below the one producing unacceptable harm, and its width decides how tightly dosing must be controlled.

This page is educational information, not medical advice. It cannot account for your medical history, medications, or risk factors. Do not start, stop or change any treatment based on it. Speak to a qualified healthcare professional who knows your case.