Immune
LL-37
The only human cathelicidin — a 37-residue host-defense peptide cleaved from hCAP-18, with direct antimicrobial and biofilm-disrupting activity plus immunomodulatory and wound-healing signaling roles.
Also known as LL37 · Cathelicidin LL-37 · hCAP-18/LL-37 · CAMP fragment
ANIMAL DATA ONLY
The evidence is animal and cell-culture work. There are no controlled human dosing trials, so every number below is convention rather than a result.
Overwhelmingly in-vitro and animal. The only substantive human work is small topical testing on venous leg ulcers.
At a glance
Dose summary
No reliable human half-life has been published for LL-37, so none is listed rather than guessed at.
No regulator and no trial set these numbers. They describe what people actually do, recorded so you can see the range rather than guess at it — which is not the same thing as a recommendation.
Reconstitution
What to draw, at the usual vial
A 5 mg vial reconstituted with 2 mL of bacteriostatic water gives 2.50 mg/mL. A typical 250 mcg dose is 0.100 mL — pull the plunger to 10 units on a U-100 syringe.
Same dose, other vial sizes
| Vial | Water | Concentration | Draw | Units | Doses |
|---|---|---|---|---|---|
| 5 mg | 2 mL | 2.50 mg/mL | 0.100 mL | 10 units | 20 |
The highlighted row is the one quoted above: the smallest listed vial that holds at least four typical doses. Change any of it — a different vial, more or less water, a different dose — on the reconstitution calculator, which draws the syringe to true U-100 graduations.
Mechanism & evidence
What it is, and what is known
The only human cathelicidin — a 37-residue host-defense peptide cleaved from hCAP-18, with direct antimicrobial and biofilm-disrupting activity plus immunomodulatory and wound-healing signaling roles. The evidence base is overwhelmingly in vitro and animal: bactericidal assays, biofilm models, rodent infection and wound studies. Human work is early — the most substantive is small early-phase testing of topically applied LL-37 on hard-to-heal venous leg ulcers; there is no approved product and no established systemic dosing trial.
The 100-500 mcg daily subcutaneous range shown is compounding-pharmacy and community convention only, scaled off the 5 mg vial that is the usual market size, and should be read as low confidence. Human half-life after injection has not been characterized, so it is left null rather than guessed. Note that LL-37 is sequence-identical to an endogenous peptide implicated in psoriasis, rosacea and lupus autoimmunity, which is a genuine reason for caution in anyone with an inflammatory skin or autoimmune condition.
Cycles are kept short (about 4 weeks) in practice rather than by evidence.
Tolerability
Reported side effects
- Injection site redness, itching, wheal or induration — LL-37 degranulates mast cells, so local histamine-type reactions are the expected complaint
- Flu-like feeling or transient fatigue after a dose
- Headache
- Flushing
- Theoretical concern with malignancy: LL-37 is pro-angiogenic and has been reported to promote proliferation in some tumor models
Hard stops
Do not use this if
- Pregnancy, possible pregnancy, or breastfeeding
- Under 18
- Active, suspected or recently treated malignancy
These are flags, not a screening. They do not replace a conversation with a clinician who knows your history.
Handling
Storage
Keep it cold, keep it dark, and label the vial with the date you mixed it. Discard anything cloudy or past the window above.
Combinations
Commonly stacked with
Stacking multiplies the side-effect surface and makes it impossible to tell which compound did what. Add one thing at a time.
References
Sources
Educational information only, not medical advice. Talk to a licensed clinician before starting, changing, or stopping anything.