Scientific context only. Not medical advice, not a recommendation to use.
At a glance
LL-37 is the only known human cathelicidin, a 37-amino-acid antimicrobial peptide generated by cleavage of the precursor protein hCAP18. In research it plays a central role in innate immune defence and wound healing, yet acts in a context-dependent manner as both anti- and pro-inflammatory and has been linked to autoimmune processes. LL-37 is not an approved drug; the evidence base is predominantly basic and preclinical.
Researched for
Antimicrobial defence (innate immunity)Wound healing and re-epithelializationImmunomodulationRole in autoimmune and inflammatory skin disorders (psoriasis, lupus)
Official status
US: Research only
No FDA approval. LL-37 is an endogenous peptide handled solely as a research substance; no approved medicinal product exists.
LL-37 is a cationic, amphipathic helical peptide and the only member of the cathelicidin family in humans. It is generated by proteolytic cleavage from the C-terminal portion of the precursor protein hCAP18 (CAP-18). Mechanistically it associates with and can permeabilize microbial membranes; in addition it modulates immune cells, influences cytokine release, exerts chemotactic activity, and can bind extracellular self-DNA. Preclinical models have described both anti-inflammatory and pro-inflammatory effects, depending on concentration and tissue context.
02
Evidence at a glance
Reading note. The distribution shows on which evidence tier each observation sits. Strong colours mark stronger evidence — weaker tiers are deliberately visible, not hidden.
4 observations · 3 tiers
Human trial
1
In vitro
2
Preclinical
1
03
What the studies show
In vitro
Zellkultur
Dürr UHN. et al. 2006
Membrane-disrupting antimicrobial activity against bacteria and other microorganisms observed in cell culture
What does NOT follow: Predominantly in-vitro findings; activity is strongly dependent on salt and serum conditions and not directly transferable to clinical efficacy.
Human trial
Mensch
Heilborn JD. et al. 2003
Promotion of re-epithelialization in skin wounds; reduced LL-37 levels reported in chronic ulcer epithelium
What does NOT follow: Observational tissue study on wound samples; shows an association, not proof of therapeutic benefit from exogenous administration.
In vitro
Zellkultur
Tokumaru S. et al. 2005
Induction of keratinocyte migration via transactivation of the EGF receptor observed in cell culture
What does NOT follow: Mechanistic in-vitro finding; clinical relevance for wound treatment is not established.
Preclinical
Mensch/Zellkultur
Dombrowski Y. et al. 2012
Pro-inflammatory role: overexpression in inflamed skin and binding to self-DNA triggering type-I interferon responses described in psoriasis
What does NOT follow: Pathophysiological model; illustrates the context-dependent dual role (pro- vs. anti-inflammatory) and possible involvement in autoimmune processes.
04
Where studies disagree
Open question
Is LL-37 anti-inflammatory or pro-inflammatory?
POSITION A
LL-37 acts protectively in innate immune defence and wound healing and can dampen excessive inflammation.
POSITION B
In certain contexts LL-37 amplifies inflammation, binds self-DNA, and has been linked to autoimmune diseases such as psoriasis and lupus.
CURRENT STATE · Current research describes LL-37 as a context-dependent molecule with a dual role; effects depend on concentration, tissue, and immunological environment. Therapeutic use is not established.
05
Pharmacokinetics
No robust pharmacokinetic human data available. A model curve is not invented.
06d
Safer use & risks
Risk notes for harm reduction — descriptive, not a usage or dosing guide.
⚠ Important — please read
This platform does NOT provide usage or dosing instructions. The points below describe risks and are meant to help avoid harm — they do not replace medical advice. Anyone who uses a substance should discuss it with a doctor.
There is no approved human use for this substance. What circulates online about amounts and frequency is self-experimentation without a safety net.
Online numbers are not a benchmark
Amounts from TikTok, YouTube and forums are mostly imitation rather than data — and are often wrongly derived from animal studies (µg/kg). Not a reliable benchmark for humans.
Sterility & infection risk
Injection solutions prepared or stored non-sterile carry an infection and abscess risk. Contamination is common with grey-market product.
Unknown product quality
Research-/grey-market product is not quality-tested: identity, purity and actual content are often unknown, and counterfeits occur.
Mind interactions
Combinations with medications or pre-existing conditions can carry risks (see the Interactions section). Clarify with a doctor beforehand.
Warning signs — seek medical help
With persistent pain, redness/swelling at the injection site, fever, shortness of breath, racing heart, chest pain or allergic reactions, seek medical help immediately.
A doctor, not a forum
Concrete questions about use and amount belong in a conversation with a doctor — not in a comment thread.
07b
Interactions & combinations
Documented interactions and contraindications from studies, prescribing information and guidelines. Where no data exists, this is stated.
Reporting of risks, NOT a combination guide. The absence of an entry does not mean „safe to combine“ but „not sufficiently studied“.
No documented interactions recorded
We have not yet found robustly documented interactions for this peptide. This does NOT mean none exist — the data is limited.
11
Legal status by country
Country
Status
Note
Checked
United States
Research only
No FDA approval. LL-37 is an endogenous peptide handled solely as a research substance; no approved medicinal product exists.
2026-06-07
Germany
Research only
No EMA or national approval. In Germany LL-37 is used exclusively in a research context; it is not an approved medicinal product.
2026-06-07
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Reconstitution calculator
Pure mg/mL maths — works like a calculator. Not a usage recommendation.
Peptides ship as a dry powder. Once dissolved in a liquid (reconstitution), this calculator answers a single question: how much substance is in one millilitre of solution afterwards?
1Enter the vial's substance amount (printed on the label).
2Enter how much solvent you add.
3Result = concentration in mg per mL.
Printed on the label
/
Liquid you add
=
2.50
mg / mL
5 mg in 2 mL gives 2.50 mg/mL — each millilitre contains 2.50 mg of substance.