LL-37
Cathelicidin antimicrobial peptide — CAMP
A host-defence peptide with direct antimicrobial activity and strong immunomodulatory effects. Its biology is double-edged, which is exactly why it is difficult to use therapeutically.
- Category
- Immune & Gut
- Half-life
- Minutes — the peptide is rapidly degraded in serum
- Cycle length
- Not established; studies address local application rather than cycles
- Level
- advanced
Overview
LL-37 is the only human cathelicidin: a peptide released by immune cells and epithelial surfaces as part of innate defence. It disrupts microbial membranes directly and also shapes the immune response — recruiting cells, influencing inflammation and supporting wound healing. That dual role is what makes it interesting and what makes it tricky. The same peptide that helps clear infections is implicated in inflammatory skin conditions and in tumour biology, so its behaviour depends heavily on context, dose and route. Most human-facing interest is in topical wound and skin applications rather than systemic use.
How it works
LL-37 is amphipathic: one face is positively charged and binds the negatively charged membranes of bacteria, the other inserts into the lipid bilayer, forming pores and disrupting the membrane. Beyond direct killing it acts as a signalling molecule, activating chemotaxis in immune cells and modulating inflammatory pathways through receptors including formyl peptide receptor 2.
Reported benefits
- Direct antimicrobial activity against bacteria, fungi and enveloped viruses in laboratory studies
- Immune-cell recruitment and modulation of inflammatory signalling
- Accelerated wound healing in some animal models
- Interest in topical and biofilm-related applications
Reported benefits describe what the published literature and user reports suggest — not a promise of outcome for any individual.
Dosing reference
There is no established systemic human dose. Research has focused on topical application and on local delivery in wound or skin contexts, with the peptide often formulated into a gel or dressing.
Because LL-37 is cytotoxic at higher concentrations and its immune effects are context-dependent, dose and route matter far more than they do for most compounds. There is no validated protocol for injection.
Community-reported: topical at low concentrations (0.1–0.5%), roughly 100–200 mcg orally, and rarely 100–500 mcg injected. Local irritation and post-dose flares are the most reported effects.
These figures are what people report using in public communities. They have not been studied, verified or checked against certificates of analysis, and they are not a recommendation, a prescription or a target to aim for.
Where the reported amounts come from
Amounts are reproduced for education only. Doses from trials cannot be assumed to suit anyone else, and community-reported amounts are frequently wrong. Self-administering unapproved compounds carries serious risk.
The research picture
LL-37 has a large mechanistic literature and a small clinical one. Laboratory work demonstrates broad antimicrobial activity, wound-healing effects and immune modulation; animal studies support topical healing applications. Clinical translation has been limited by the peptide's toxicity to human cells at effective concentrations and by its short half-life. It is also implicated in disease rather than only in defence: elevated LL-37 is associated with rosacea and psoriasis, and the peptide has been reported to influence tumour behaviour in some cancer models. That makes systemic self-administration an unusually speculative idea, even by the standards of research peptides.
Preclinical & non-clinical data
An antimicrobial cathelicidin peptide with potent activity against bacteria in cell studies, alongside documented cytotoxicity and pro-inflammatory effects. There is no human safety study of injected use.
Non-clinical data comes from cells and animals unless stated otherwise. It answers whether a compound is worth studying in people — not whether it is safe or effective in them.
What users report
Two distinct reporting groups. Topical users describe calming of irritated skin or sinus symptoms, and burning or stinging at higher concentrations — which lines up with its known inflammatory activity. A smaller group uses it orally for gut symptoms, and a few report injected use in chronic-inflammation protocols with flares, malaise and site reactions after dosing. The injected accounts are the ones to treat most cautiously; that is the route with the least justification and the most reported harm.
Where these reports come from
These are unverified personal accounts collected from public sources. They are not evidence of effectiveness or safety, they have not been independently checked, and they are not a recommendation to use anything described.
Possible side effects
- Local irritation and redness with topical use
- Cytotoxicity to human cells at higher concentrations
- Injection-site reactions
- No systemic human safety data
Safety notes
No established human dose or safety record for systemic use. Because LL-37 drives inflammation and has been linked to inflammatory skin disease and to tumour-related signalling in some models, anyone with an autoimmune or inflammatory condition, or a history of malignancy, has particular reason to avoid it. It is also degraded rapidly in serum, so injected dosing is pharmacologically unreliable.
Stacking
Sometimes combined in topical wound formulations with other repair compounds. Injected combinations have no evidence base and multiply unquantified risks.
Related compounds
Thymosin Alpha-1
Tα1, Zadaxin
Immune & Gut
An immune-modulating peptide with actual clinical approvals.
VIP
Vasoactive intestinal peptide — 28 amino acids
Immune & Gut
A signalling peptide central to immune tolerance and gut function.
KPV
Lysine-Proline-Valine
Immune & Gut
A tiny tripeptide for the gut side of inflammation.