Healing & Recovery

LL-37

Cathelicidin · hCAP18

LL-37 is the mature 37-residue human cathelicidin peptide cleaved from hCAP18. Pore-forming antimicrobial and innate-immune signaling biology is real in vitro and in animal models. Injectable research-chem vials are not an antibiotic, not a Lyme drug, and not a MRSA protocol. Vitamin D induces endogenous CAMP expression; that is not the same as injecting a 5 mg vial.

Not FDA-approved - research chemical
Reviewed by CalcMyPeptide Editorial Team
Last updated: August 2026Evidence: Low3 peer-reviewed citations
Typical research dose
50-200 mcg/day
Frequency
1× daily
Half-life
Hours-class in some models; SKU PK unpublished. The ~4 h catalog figure is not a human injection study we will treat as fact.
Common vials
5 mg
CAS
154947-66-7
Molecular weight
4493.3 g/mol

Use-case scores

0–10 against the evidence we have, not a gym ranking. Hidden domains do not apply here.

  • Immune4.5/10

    Multi-lab AMP and innate-immune biology. Human injectable efficacy for infection is not a completed drug program. Below the 5.5 animal ceiling after the “vial ≠ endogenous CAMP” haircut.

  • Injury & tissue3.5/10

    Keratinocyte migration and wound models exist. Not a tendon peptide. Not a substitute for antibiotics or wound care.

Compound card

Sequence
LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES
Class
Human cathelicidin (mature 37-mer from hCAP18)
Formula
C205H340N60O53
Status
Not FDA-approved · research use
Dose it
5 mg + 2.5 mL BAC water → 2 mg/mL · 50 mcg ≈ 3 units (U-100)
Open in calculator

How it works

LL-37 is the only human cathelicidin antimicrobial peptide, the 37-residue C-terminal fragment of hCAP18. Agerberth et al. 1995 (PNAS, PMID 7529412) cloned it as FALL-39; Gudmundsson et al. 1996 (PMID 8681941) established the mature LL-37 processing. It is amphipathic: it can pore bacterial membranes and it talks to innate immune receptors (FPRL1/FPR2, TLR modulation). Vitamin D induces the CAMP gene. That is endogenous biology, not a reason to inject a 5 mg vial.

Human therapeutic development has been mostly topical/wound and device-adjacent. Injectable research-chem calendars (50–200 mcg, Herxheimer folklore, Lyme/MRSA protocols) are not an antibiotic label. Hemolysis and pro-inflammatory signaling at high concentration are why “more AMP” is not automatically better.

Source: PMID: 18082616

Not an antibiotic substitute

Do not delay indicated antimicrobials or wound care because a cathelicidin page exists. Research-chem LL-37 is unlabeled.

Goal context

Innate immunity vs a named infection

CAMP biology is why people search this page. Lyme, Candida, and MRSA are diagnoses. Pore-forming peptides in a dish do not become a home antibiotic.

Vitamin D is not the vial

Vitamin D upregulates endogenous LL-37. Correcting deficiency is ordinary medicine. It is not equivalent to injecting synthetic LL-37.

Background & History

LL-37 is the mature 37-residue human cathelicidin cleaved from hCAP18. Agerberth 1995 cloned it as FALL-39; Gudmundsson 1996 established LL-37 processing. Membrane-active AMP and innate-immune signaling biology is real. Injectable research-chem vials are not an antibiotic and not a Lyme or MRSA protocol. Vitamin D induces endogenous CAMP expression; that is not the vial.

Research Use Cases

  • ✓Identity: the only human cathelicidin AMP
  • ✓Wound/keratinocyte models (preclinical)
  • ✓Not a substitute for indicated antimicrobials

Dosing

PhaseDoseFrequencyNotes
Community research-chem (unlabeled)50–200 mcgDaily or 5 on / 2 off SCCopied ranges. Not a label. 50 mcg is the usual “see if it stings” start, not a PK titration.

Administration

Route / form
Subcutaneous injection from a reconstituted vial. Topical SKUs are a different presentation.
Timing
No PK mandate. Morning is habit.
Empty stomach?
No - Food timing is not critical.

Timeline

First week
Local sting is common. Flu-like “Herx” stories are not a monitored kill curve.
Weeks 2–4
No honest infection-clearance timeline for a research vial.

Who it is for

AMP identity / innate-immune research

Moderate

This is the human 37-mer. Biology is real. Drug is not.

Named infection treatment

Low

Wrong tool. See a clinician.

Reconstitution

VialWaterConcentrationExample dose
5 mg2.5 mL BAC2 mg/mL100 mcg = 0.05 mL = 5 units on a U-100 syringe

Change vial size or water volume? Open the reconstitution calculator.

Safety & Considerations

Research-use AMP. Can irritate at the site. Theoretical hemolysis and pro-inflammatory signaling at high concentration. Not for use as a standalone antimicrobial. Active systemic infection belongs in clinic, not in a peptide calculator.

Regulatory & Legal Status

FDA Status (US)
Research Only
WADA Status (2026)
Not Listed

Not currently on the WADA 2026 Prohibited List. Policies may change - verify before competition.

Classification

Research Chemical

US Compounding: Not eligible / not available

⚠️ This information is for educational purposes only and may not reflect the most current regulatory updates. Always verify with official FDA, WADA, and jurisdiction-specific sources before use.

Limits of current evidence

  • No approved injectable LL-37 antibiotic. Topical/wound research is not a SubQ infection protocol.
  • PMID 7529412 is FALL-39 cloning, not a human RCT. Do not cite it as clinical proof.
  • Herxheimer-like “die-off” stories are community interpretation, not a monitored antimicrobial endpoint.
  • High concentrations can be cytotoxic/hemolytic in vitro. Start-low folklore exists because of that, not because of a Phase 2 dose-finding trial.

Verdict

LL-37 is a real human AMP with a real cloning paper. It is not a Lyme drug, not MRSA-in-a-syringe, and not “stronger than antibiotics.” Use this leaf for identity and vial math. Take infections to a clinician.

Interactions & Contraindications

High concentrations can be cytotoxic/hemolytic in vitro. Local sting is common. Immunostimulatory AMP biology is a caution in autoimmunity. Not an antibiotic substitute.

Synergies & Common Stacks

+ BPC-157 →

People pair them in wound folklore. Complementary marketing is not a synergy RCT. Infections still need indicated care.

Appears in goal guides

Goal guides are maps, not clinic protocols. A mention here is not a treatment plan.

Immune Resilience & Post-Viral Stack

Thymosin α1 and Thymalin identity. Zadaxin is not a US NDA. This is not a viral-pathogenesis or thymic-regeneration treatment page.

View Protocol →

Immune Optimization Protocol

Thymic cytomax (Vladonix) plus Endoluten and Bonomarlot, then Thymosin Alpha-1 and Selank, with LL-37/KPV as acute experimental tools.

View Protocol →

Frequently Asked Questions

Does LL-37 treat Lyme or MRSA?▼
No indication we will print. Membrane-active AMP biology is real in vitro. That is not a borrelia or MRSA protocol.
What is a typical research-chem dose?▼
Community range is 50–200 mcg SC. Start at the low end because local sting and theoretical cytotoxicity are real. Not a label.
How do I reconstitute a 5 mg vial?▼
This leaf’s default is 5 mg + 2.5 mL BAC = 2 mg/mL. 100 mcg is 0.05 mL (5 units). Use the calculator if you change water.
Is the half-life 4 hours?▼
That is a catalog estimate. We will not treat it as a human injection PK study.
Why do people mention Vitamin D?▼
The CAMP gene is vitamin-D responsive. That is endogenous expression, not vial math.
Can I stack it with BPC-157?▼
People do (wound folklore). Complementary marketing is not a synergy RCT. Infections still need indicated care.
Is it FDA-approved?▼
Not as an injectable antibiotic. Do not confuse endogenous CAMP with a drug approval.
What about autoimmune disease?▼
AMPs can be immunostimulatory. Unlabeled use in autoimmunity is a clinician problem, not a DIY plus.

References

  1. Agerberth B, Gunne H, Odeberg J, et al. “FALL-39, a putative human peptide antibiotic, is cysteine-free and expressed in bone marrow and testis.” Proc Natl Acad Sci U S A (1995). PMID: 7529412
  2. Gudmundsson GH, Agerberth B, Odeberg J, et al. “The human gene FALL39 and processing of the cathelin precursor to the antibacterial peptide LL-37 in granulocytes.” Eur J Biochem (1996). PMID: 8681941
  3. Vandamme D, et al. “The human cathelicidin LL-37 - a multifunctional peptide involved in infection and inflammation in the lung.” Pulm Pharmacol Ther (2012). PMID: 22584291

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