human cathelicidin antimicrobial and immunomodulatory peptide

LL-37

aka cathelicidin LL-37 · LL37 · ropocamptide

Evidence grade
Grade D: Preclinical only
for injected or nasal use for infections, biofilms and CIRS
User score everyone · n = 23
US FDA Not approved checked 2026-11-13
WADA 2026 Prohibited (S0) checked 2026-11-13
EU Investigational topical use appears in the EU trial register; EU marketing authorization not found. · checked 2026-11-13
  • D injected or nasal use for infections / CIRS
  • F topical wound healing (trialled, failed)

Goals: Recovery & injury · Immune Compare with another peptide →

User reports

approximate — combined from two independent Reddit reads

Men 45–60

0 men aged 45–60

No reports in this group yet.

All men

0 men

No reports in this group yet.

Everyone

23 people

  • Positive: 4 of 23 (17%)
  • Mixed: 6 of 23 (26%)
  • Negative: 3 of 23 (13%)
  • No effect: 2 of 23 (9%)
  • Unclear: 6 of 23 (26%)
Benefits reported of 23
Benefits reported (n = 23)
ItemReports
Immune9 of 23 (39%)
Gut2 of 23 (9%)
Inflammation1 of 23 (4%)
Other1 of 23 (4%)
Side effects reported of 23
Side effects reported (n = 23)
ItemReports
Other11 of 23 (48%)
Insomnia1 of 23 (4%)
Joint pain1 of 23 (4%)
Why people stopped of 23
Why people stopped (n = 23)
ItemReports
Side effects2 of 23 (9%)
Other1 of 23 (4%)

Stopped 2 of 23 (9%) Used with other compounds 9 of 23 (39%)

User reports are anecdata, not evidence: self-selected, unverified, often combined with other compounds.

In their words

  • “No effect for me”

  • “Worked pretty well along with TA-1 for stomach problems”

  • “No it caused temporary reactive arthritis!”

  • “it definitely knocked back some infections but did not clear everything”

  • “Yes, ran 3 cycles over like 6mos to help kill a long term Lyme infection.”

  • “LL increased my inflammation & with knees and joints it made & caused sleepless painful nights. I did try it 2 times”

  • “Felt like I had to flu for 3-4 days. Then things leveled out. It definitely knocked something's back but unfortunately did not cure me.”

  • “Helped me to cure chronic sinusitis, I was so tired of using antibiotics every month! Used in spray, 200 mcg daily”

Read summaries and method notes

Read 1. No man aged 45–60 and no explicitly male reporter. Eight deduplicated users with polarized outcomes: gut/infection improvement (one with TA-1), "knocked back some infections" over three months, no effect, temporary reactive arthritis, sexual anhedonia after three 250 mcg doses, and an early die-off reaction. Stacking with TA-1 or other peptides was common.

Read 2. No verifiable age or sex. Nineteen users from 12 threads: 6 mixed, 6 unclear, 3 positive, 2 negative, 2 no effect. Partial or full immune/infection wins (8, e.g. pushing back Lyme or mould load, healing chronic sinusitis with a 200 mcg spray) against a very high rate of acute Herxheimer/die-off reactions and inflammatory flares (10: flu-like symptoms, fever, brain fog, a bladder-pain flare), plus joint pain with insomnia. Reactions came in the first 2–4 days and eased with lower doses; effective cycles lasted 4–26 weeks, often with relapse. Commenters warned of autoimmune flare risk via TLR activation.

Note 1. No age/sex-qualified users. The same username reporting LL-37 plus TA-1 in two threads was deduplicated. One Lyme-thread report was only on day 3 and coded unclear.

Note 2. No explicit age/sex. A 'my RS' report was excluded. Heavy confounding from concurrent thymosin alpha-1, BPC-157, herbal protocols and chronic infection syndromes.

Each read counted people independently. Overlap between the two reads is estimated from shared threads and removed; counts are approximate. How we count.

Summary

Human cathelicidin antimicrobial peptide. 37-amino acid alpha-helical peptide. MW: ~4,493 Da. Endogenously produced — vitamin D upregulates its expression.

Proposed mechanism

LL-37 is your body's primary antimicrobial peptide — broad-spectrum, multifunctional:

  1. Direct antimicrobial — disrupts bacterial, fungal, and viral membranes. Active against MRSA, P. aeruginosa, E. coli, C. albicans
  2. Biofilm disruption — laboratory findings do not establish that nasal or injected LL-37 eradicates patient biofilms or treats CIRS.
  3. Immune modulation — recruits immune cells to infection sites, promotes wound healing, modulates TLR signaling
  4. Anti-endotoxin — neutralizes LPS (bacterial lipopolysaccharide), reducing systemic inflammatory response to gram-negative bacteria

Key distinction vs KPV: Their laboratory mechanisms differ; clinical combination benefits and a comparative safety ranking are not established.

Safety

  • Inflammation and dermatitis in topical wound trials
  • Case report of atypical and blistering skin eruption after intratumoral injection
  • Preclinical male reproductive and tissue-specific tumor-promotion concerns
  • Potential immunogenicity and peptide impurities
  • Systemic and intranasal human safety not established

From labels, regulators and trials. No signal in small studies ≠ safe.

Evidence D injected or nasal use for infections, biofilms and CIRS

D stands for the marketed systemic use: no human trial of it exists. Human trials do exist for topical wound healing only, and the largest (148 patients) failed overall - so if the page presents wound healing as a use, that use is F, not a reason to raise the grade.

Human trials · 4

  1. PMID 250417402014double-blind placebo-controlled RCT 34 people

    Patients with hard-to-heal venous leg ulcers

    The 0.5 mg/mL topical group showed a faster healing-rate measure; this small exploratory result was not confirmed overall in the larger phase IIb trial. Source

  2. PMID 346872532021multicentre double-blind placebo-controlled RCT 148 people

    Patients with hard-to-heal venous leg ulcers

    Topical LL-37 did not significantly improve healing in the overall population; a post hoc large-ulcer subgroup was hypothesis-generating. Source

  3. NCT040985622023double-blind placebo-controlled RCT 25 people

    Adults with mostly uninfected or mildly infected diabetic foot ulcers

    Granulation index improved, but ulcer area and bacterial-count differences were not statistically significant. Source

  4. NCT022253662021open-label single-arm phase I/II 4 people

    Patients with injectable melanoma lesions

    Very small intratumoral dose-finding study; results were posted in 2021 and cannot establish comparative efficacy. Source

Bar length = trial size on a log scale.

Dose ranges

Reported ranges from labels and studies, with context. Not a recommendation.

  • clinical trial, venous leg ulcers, topical plus compression
    0.5 or 1.6 mg/mL, equivalent to 12.5 or 40 micrograms/cm², twice weekly for 13 weeks Source
  • clinical trial, diabetic foot ulcers, topical cream
    0.5 mg/g cream twice weekly for 4 weeks Source

Editorial ratings EDITORIAL

Editors’ judgement, 0–5. Opinion, not data; separate from grade and user score.

Not rated yet.

Sources

  1. pubmed.ncbi.nlm.nih.gov/25041740/
  2. pmc.ncbi.nlm.nih.gov/articles/PMC9298190/
  3. pmc.ncbi.nlm.nih.gov/articles/PMC10514151/
  4. clinicaltrials.gov/study/NCT02225366
  5. fda.gov/advisory-committees/pharmacy-compounding-advisory-committee/meeting-pharmacy-compo
  6. pubmed.ncbi.nlm.nih.gov/29665030/
  7. pmc.ncbi.nlm.nih.gov/articles/PMC13457997/
  8. clinicaltrials.gov/ct2/show/NCT04098562
  9. clinicaltrials.gov/study/NCT04098562
  10. fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-pres
  11. fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-c
  12. wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf

Reddit threads read · 14

5 further sources on commercial or non-primary hosts not listed.

Research checked 2026-11-13.