# LL-37 — dosage, half-life & reference guide | PepVault

Source: https://pepvault.app/peptides/ll-37

Last updated: 2026-09-26

[Library](https://pepvault.app/peptides) [Healing & recovery](https://pepvault.app/peptides#healing) reviewed September 2026

# LL-37 Dosage, half-life & reference guide

Also known as Cathelicidin · hCAP-18 · CAP-18

Your body's own antimicrobial peptide. In lab studies it kills bacteria, fungi and some viruses, and it also steers immune responses.

- **Studied range:** 100–300 mcg
- **How often:** Daily
- **Evidence:** Emerging
- **Route:** SubQ injection

Studied in research — not a recommendation.

[LL-37 dose guide](https://pepvault.app/lab/dosage/ll-37)

## How it works.

Human antimicrobial peptide with broad-spectrum antimicrobial activity. In lab and animal studies it modulates innate immunity, breaks up biofilms and promotes wound healing; it can be anti- or pro-inflammatory depending on context.

**Commonly reported:** Noticeable injection-site redness or itching, and for some a flu-like, achy feeling in the first days. As a drug it has only been tested as a topical treatment for leg and foot ulcers, with mixed results; injected LL-37 hasn't been studied in people.

## Where LL-37 works.

- ### Skin & hair

  **In people.** As a drug it has only been tested as a topical treatment for leg and foot ulcers, with mixed results.
- ### Immune system

  **In animals.** In lab and animal studies it modulates innate immunity, breaks up biofilms and promotes wound healing.

An area lights for what a peptide is used for and what people report, with the evidence beside it. It isn’t a promise that it works there.

## Week by week.

What to expect in the first 8 weeks

1. Day 1–7 Community

   ### Some feel a flu-like wave early

   Commonly reported: a mild flu-like or achy feeling in the first few days for some users, usually passing within days. LL-37 stirs the immune system on its own, which may be why. If it's strong or doesn't settle, stop and talk to your clinician.

   The science

   LL-37 is the active fragment of cathelicidin hCAP-18. In lab studies it disrupts bacterial membranes and breaks up established biofilms. The community credits the early "herx-like" feel to dying microbes releasing endotoxin, but no study has shown that; LL-37 is itself immune-stimulating (Kahlenberg & Kaplan 2013), a simpler explanation.

   Sources

   - Vandamme et al. (2012)
   - Kahlenberg & Kaplan (2013)

   Updated Sep 2026
2. Day 7–21 Community

   ### Weeks 1 to 3: check what changed

   Commonly reported around weeks 1 to 3, by those who notice a change: more energy and fewer nagging symptoms. Results vary widely and injected LL-37 hasn't been studied in people, so compare how you feel now with your starting point.

   The science

   LL-37 also modulates adaptive immunity via TLR signaling and recruits neutrophils in lab and animal studies. In the one randomized trial that measured it, an LL-37 cream on mildly infected diabetic foot ulcers improved granulation but didn't significantly lower bacterial colonization over 4 weeks (Miranda 2023).

   Sources

   - Dürr et al. (2006)
   - Kahlenberg & Kaplan (2013)
   - Miranda et al. (2023)

   Updated Sep 2026
3. Day 21–28 Community

   ### Cycle wrap-up — time to assess

   Most LL-37 runs cap at 2–4 weeks. Symptoms flat or improved? Good time to stop and let the body re-equilibrate before deciding on another round. Longer runs don't have data behind them.

   The science

   Endogenous LL-37 has roles in both defense and inflammation regulation — chronically elevated levels are implicated in psoriasis and rosacea flare activity. The short-cycle convention is conservative because there's no long-term exogenous dosing data in humans.

   Sources

   - Morizane & Gallo (2012)

   Updated Apr 2026
4. Any day Community

   ### What LL-37 is built on

   LL-37 has strong mechanistic data as a natural antimicrobial and a growing body of research in chronic infection and biofilm contexts. Still early on the clinical side — most exogenous dosing is community-reported.

   The science

   The parent peptide (hCAP-18) is a human cathelicidin essential for innate immunity. Exogenous LL-37 has been studied topically in diabetic ulcers and investigated for C. diff and cystic fibrosis indications. No completed late-stage human trials for injectable use.

   Sources

   - Vandamme et al. (2012)
   - Kahlenberg & Kaplan (2013)

   Updated Apr 2026
5. With KPV and Thymosin Alpha-1 Community

   ### An immune-support trio

   Three immune layers at once: LL-37 works on microbes directly, KPV calms inflammation, and thymosin alpha-1 tunes the adaptive side. Commonly stacked for immune support; users judge it by how they feel over several weeks.

   The science

   The three act on different immune layers: innate antimicrobial (LL-37), inflammatory damping (KPV) and T-cell orchestration (Tα1). No study has tested them together; the pairing rests on their separate lab, animal and (for Tα1) clinical research.

   Sources

   - Kahlenberg & Kaplan (2013)

   Updated Sep 2026

Day 1 is the day you start it.

## Mixing and a typical run.

Example numbers

### Reconstitution example

Reconstitute a 5 mg vial of LL-37 with 2 mL of bacteriostatic water and a 200 mcg dose is 8 units on a U-100 syringe, about 25 doses per vial.

- **Vial:** 5 mg
- **Water:** 2 mL
- **Amount:** 200 mcg

Draw to **8 units**

0.3 mL insulin syringe · 30 units

[Mix it in the Reconstitution Lab](https://pepvault.app/lab) [Open the calculator](https://pepvault.app/tools/reconstitution-calculator)

### Run notes

- **Cycle:** Short cycles of 2–4 weeks due to limited data. Conservative approach advised. Community practice — opinions vary. Not a clinical recommendation.
- **Timing:** SubQ injection. Timing flexible.
- **Route:** SubQ injection
- **Stacks:** Thymosin Alpha-1, KPV

## Safety.

### Common side effects

- Injection site pain
- Redness
- Mild systemic inflammation

## Goes with.

- [Thymosin Alpha-1](https://pepvault.app/peptides/thymosin-alpha-1)
- [KPV](https://pepvault.app/peptides/kpv)

## Questions people ask.

### What is LL-37?

Your body's own antimicrobial peptide. In lab studies it kills bacteria, fungi and some viruses, and it also steers immune responses.

### How is LL-37 dosed in research?

The research range for LL-37 is 100–300 mcg, daily or EOD. Studied in research — not a recommendation.

### How long does LL-37 last?

The half-life of LL-37 is unknown in humans (short; broken down by proteases).

### What do people report on LL-37?

Commonly reported on LL-37: noticeable injection-site redness or itching, and for some a flu-like, achy feeling in the first days. As a drug it has only been tested as a topical treatment for leg and foot ulcers, with mixed results; injected LL-37 hasn't been studied in people.

### Is LL-37 safe?

The research basis for LL-37 is emerging: primarily preclinical / limited human data. Common side effects in the library: injection site pain, redness and mild systemic inflammation.

### What does LL-37 stack with?

Common stacks for LL-37: Thymosin Alpha-1 and KPV.

## Research.

The literature

### Search the latest research

[PubMed](https://pubmed.ncbi.nlm.nih.gov/?term=LL-37) [Google Scholar](https://scholar.google.com/scholar?q=LL-37)

## Reference.

- **Cadence:** Daily Daily or EOD
- **Half-life:** Unknown in humans (short; broken down by proteases)
- **Research basis:** Emerging Primarily preclinical / limited human data

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## Free tools

- [LL-37 dose guide](https://pepvault.app/lab/dosage/ll-37)
- [Reconstitution Lab (3D)](https://pepvault.app/lab)
- [Injection guide (3D)](https://pepvault.app/lab/injection)
- [Peptide Sky (3D)](https://pepvault.app/lab/sky)
- [Peptide tier list](https://pepvault.app/lab/tiers)
- [Reconstitution calculator](https://pepvault.app/tools/reconstitution-calculator)
- [Half-life & active level](https://pepvault.app/tools/peptide-half-life-calculator)

PepVault for iPhone

## Track LL-37 in PepVault

Log every dose and keep your vial and the doses left in it. 7 days free on the yearly plan for new subscribers.

[Download on the App Store](https://apps.apple.com/app/apple-store/id6779318649?pt=129020030&ct=peptides-cta&mt=8)

[Open the calculator](https://pepvault.app/tools/reconstitution-calculator) [How the vial count works](https://pepvault.app/peptide-vial-tracker-app) [Explore the live demo](https://pepvault.app/login)

Reviewed September 2026 [How we check the library](https://pepvault.app/about#library)

PepVault is a research and tracking resource, not medical advice. Ranges are what studies used, never a dose for you. Brand names are trademarks of their owners; PepVault is independent of them.

PepVault is a private research and tracking tool, not medical advice. The information here is reference material from published literature and community use — always verify it and discuss any protocol with a qualified clinician before changing it.

© 2026 PepVault