LL-37 is a human cathelicidin antimicrobial peptide. The source describes it as a 37-amino-acid, positively charged helical fragment derived from hCAP-18 and involved in innate immune defense against microbes. It is a studied part of human biology, but the source also states that LL-37 is not an approved drug.

The source describes LL-37 as cationic and amphipathic, which supports interaction with negatively charged microbial membranes and membrane disruption. It is also reported to act as an immune signaling molecule, including LPS neutralization, inflammatory-response modulation, immune-cell recruitment, and support for epithelial repair processes.

Is LL-37 FDA approved?

No. The source lists LL-37 as not FDA approved and describes its current status as investigational, with clinical trials for wound healing and FDA Category 2 restricted language tied to limited safety and immunogenicity data.

What side effects are reported for LL-37?

Reported concerns in the source include injection-site reactions, skin ulcers or burning, allergic reactions, possible histamine release, possible contribution to autoimmune conditions, high-dose toxicity concerns, and limited long-term safety data.

What dose is reported for LL-37?

The source reports a community typical dose of 100-200 mcg daily, a community range of 50-300 mcg daily, and once-daily frequency. It also lists subcutaneous injection or topical administration. These are source-reported values, not dosing guidance.

Immune Clinical Trials - human trials under way

LL-37

Also known as: Cathelicidin, CAP18

At a glance

PeptiGuide dataset · reviewed Aug 2026

What it is

Human cathelicidin antimicrobial peptide researched for innate immune and wound-healing biology.

Status

Clinical Trials

Evidence level: human studies

Typical dose

100–200mcg

Subcutaneous injection or topical

Researched for

Antimicrobial, infections, biofilm disruption, wound healing

Trial progress

PrePreclinical
IPhase I
IIPhase II
IIIPhase III
IVPhase IV
FDAFDA approved

Phase II - Emerging human evidence with important limitations

Use the tools

In plain language

Human cathelicidin antimicrobial derived from hCAP-18.
Source describes a 37-amino-acid, positively charged helical peptide involved in innate immune defense.
Not FDA approved; source lists investigational status with clinical trials for wound healing.
Source-reported typical dose is 100-200 mcg daily, with or topical administration listed.
Researched for antimicrobial activity, infections, biofilm disruption, and wound healing.

How it's thought to work

LL-37 is described as a positively charged, amphipathic host-defense that can associate with negatively charged microbial membranes and disrupt them. Beyond direct antimicrobial effects, the source reports signaling roles that include neutralizing bacterial LPS, shaping inflammatory activity, recruiting immune cells to sites of injury or infection, and supporting epithelial repair. The source notes production in epithelial tissues such as skin, gut, and lung, as well as immune cells including neutrophils.

What the research shows

Where the research stands

The source presents LL-37 as a well-studied endogenous component of human innate immunity, with literature support for broad antimicrobial activity, membrane disruption, and distribution across epithelial and immune tissues. It also reports exploratory research on LL-37 or related mimics in laboratory anticancer models, Helicobacter pylori host-defense research, and ocular-surface pathogen contexts. The evidence described is strongest for LL-37 as a natural immune ; deliberate administration remains experimental in the supplied source, and the source flags that LL-37 may worsen inflammation in some disease settings.

What it shows

✓ Human studies

Emerging human evidence with important limitations

△ Limitations

Study protocols describe research and are not dosing recommendations.

Bottom line: Investigational; source notes clinical trials for wound healing and FDA Category 2 restricted status due to limited safety data and immunogenicity concerns. Not FDA Approved

Typical dosing

CommunityCommunity dataset

100–200 mcg

daily

50 mcgfull range seen300 mcg

Community-reported dosing is described for antimicrobial, infection, and biofilm-disruption contexts, with some reports of higher acute-use amounts; this does not establish safety or efficacy.

Research dosing

Study-specific protocolsHuman trials under way - protocols are study-specific

Doses observed in studies

100-200 mcg subcutaneous

Research Literature - Observed in studies

Study protocols describe research and are not dosing recommendations.

Duration: Variable by protocol
Administration: Subcutaneous injection or topical

Timing & administration

Best time to take

Morning

As directed, typically once daily

Food recommendation

With or without food

Why this timing?

The source favors morning timing in the context of LL-37's antimicrobial and immune-surveillance role, but this rationale is source-reported and not established dosing guidance.

Possible side effects

Not everyone experiences these. Individual responses vary with dose, duration, and personal factors.

Injection-site reactions
Skin toxicity
Allergic reactions
Histamine release
Possible contribution to autoimmune conditions
High-dose toxicity concerns
Limited long-term safety data

Not everyone experiences side effects, and severity can vary by context, purity, route, and individual health factors.

Sources

PubMed ClinicalTrials.gov FDA.gov

Frequently asked questions

Sequence

Leu-Leu-Gly-Asp-Phe-Phe-Arg-Lys-Ser-Lys-Glu-Lys-Ile-Gly-Lys-Glu-Phe-Lys-Arg-Ile-Val-Gln-Arg-Ile-Lys-Asp-Phe-Leu-Arg-Asn-Leu-Val-Pro-Arg-Thr-Glu-Ser

One open dataset

Every fact on this page - doses, side effects, references - comes from the same PeptiGuide dataset that powers the Tracker, Compare, and the Lab.

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Educational resource, not medical advice. Talk to your clinician before acting on anything here.

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LL-37

In plain languageIn plain language

How it's thought to workHow it's thought to work

What the research showsWhat the research shows

Typical dosing

Research dosing

Timing & administrationTiming & administration

Possible side effectsPossible side effects

SourcesSources

Frequently asked questionsFrequently asked questions

What does LL-37 do?

How does LL-37 work?