LL-37

What people use it for

• Chronic wounds and leg ulcers (clinical research)
• Infections and immune support (popular use)

What LL-37 does in the body

Produced by white blood cells and skin cells. It can punch holes in bacterial membranes, disrupt biofilms, neutralise bacterial toxins and recruit immune cells. It also promotes wound healing, but too much is linked to inflammatory skin conditions like psoriasis and rosacea.

Strength of evidence

Limited: lab and animal data plus small human trials (e.g. topical use for venous leg ulcers).

Look up the evidence

• Reviews on PubMed: Summaries of the published research
• Clinical trials on PubMed: Published studies in people
• ClinicalTrials.gov: Registered trials, past and ongoing

Live searches of official databases. New to the terms? See the glossary.

Reported side effects & risks

• Injection-site pain and redness
• Possible worsening of inflammatory skin conditions
• Unknown long-term effects

Who should avoid it or take extra care

• Psoriasis, rosacea or other inflammatory skin or autoimmune disease (LL-37 is linked to these)
• Pregnant or breastfeeding

Not a complete list. Check with a doctor or pharmacist about your own health and medicines.

Regulatory status

Not approved.

How it's taken

Route: Injection (unofficial use)

How long it lasts (half-life): Short; not well established

Storage

Unreconstituted (powder) vials are usually kept refrigerated or frozen and away from light. Once mixed with bacteriostatic water, keep refrigerated and do not freeze; follow the supplier's stated beyond-use date.