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Immune support

LL-37

The body’s own germ-fighting peptide, discussed for immunity.

StatusInvestigational (topical); not approved (EU/UK/US)
How well studied in peopleSmall human studies
Experts quoted3 experts

iNot medical advice. We don’t recommend any dose. Every dose below is a quote from the person named, describing their views or their own use. LL-37 is not an approved medicine in the EU, UK or US. It has been tested only as a topical treatment for leg ulcers.

What experts say about dosing

2 statements from 2 people. Each one is word for word: we add punctuation only and mark cuts with […]. The chips repeat the exact words used.

Vigorous SteveBodybuilding coach and YouTuber (VigorousSteve)

Gut “reset” protocol

Dose
“about 500 microgr”
How often
“per day”
How long
“about 20 days or 3 weeks”
How taken
“inject”

“it's basically a naturally occurring antibiotic that you can inject. l37 will work systemically but potentiates most of its effects in the intestinal tract. ideally you run that about 500 microgr per day for about 20 days or 3 weeks in duration, after which you discontinue it, and you probably never have to use this compound ever again because it will kill everything, so that means that you'll have to completely repopulate your gut microbiome after you're done with ll37”

Watch at 0:46End-Stage FULL Gut Microbiome Reset With Peptide LL-37 #shorts (VigorousSteve) · 29 Aug 2022

Context: From a 90-second short. “microgr” is where the captions cut off “micrograms”. He follows with advice to eat fermented and raw foods afterwards. Not described as his own use.

Ben GreenfieldFitness and longevity author; host of Ben Greenfield Life

Immune stack (dosing guidelines)

Dose
“100mcg”
How often
“2x/day”
How long
“for 4–6 weeks”
How taken
“Subcutaneous injection”

“Dosing Guidelines: 100mcg 2x/day for 4–6 weeks. Administration Route: Subcutaneous injection”

Read the sourceBen’s Peptide Stack for Recovery, Explosive Gains, & Ageless Vitality (bengreenfieldlife.com) · 17 Sep 2024

Context: Published as “Dosing Guidelines” in an article on his own site; not described as his own use.

What experts say about safety

4 statements from 3 people about risks and how strong the evidence is.

Ben GreenfieldFitness and longevity author; host of Ben Greenfield Life

Own use

“LL-37, an anti-microbial peptide, helped my gut recover from a nasty bout of giardia thanks to a water filter snafu during a wilderness survival course.”

Read the sourcePeptides Part 1 (bengreenfieldlife.com) · 11 Jan 2022

Context: No dose given.

Warning: die-off reaction

“Warning: If you have SIBO, the die-off and Jarisch-Herxheimer Reaction from LL-37 can be uncomfortable and may involve flu-like symptoms and diarrhea for up to two weeks.”

Read the sourceBen’s Peptide Stack for Recovery, Explosive Gains, & Ageless Vitality (bengreenfieldlife.com) · 17 Sep 2024

Context: Same article. He goes on to say many people then see their SIBO symptoms resolve; we have not found trial evidence for that.

Vigorous SteveBodybuilding coach and YouTuber (VigorousSteve)

Own use: one course

“I think I heard it over a decade ago about ll37 and I never had the opportunity to try it until I hooked up with the compounding pharmacy here in Thailand, right, so one course for me really improved my gut microbiome and my ability to digest. again I did have to repopulate my gut microbiome afterwards”

Watch at 15:02STEROIDS Ruined Your Gut? The CURE Is Within! (VigorousSteve) · 5 Feb 2022

Context: From the full video that his LL-37 short (above) is taken from; earlier in it he describes the same “about 500 micrograms per day for about 20 days” course, combined with a fast.

Dr Kent HoltorfPhysician; host of the Peptides and Longevity podcast (Big Doc Energy)

Antimicrobial peptide

“antimicrobial peptides, um, ll37 is a big one, very broad range of antimicrobial, um, properties that your body secretes, actually stem cells secrete them, it also stimulates stem cells”

Watch at 20:47Peptides 101 (Peptides and Longevity podcast / Big Doc Energy, Dr Kent Holtorf) · 5 Feb 2025

Context: No dose given.

Go deeper

What the research used

Context, not a dosing guide. The human trials applied LL-37 to the skin of chronic leg ulcers. None tested injection. They are not a guide to injected use.

Human trials

StudyStudied inWhat the study usedWhat it found
Grönberg et al., 2014, Wound Repair RegenPubMed 2504174034 people with venous leg ulcersTopical 0.5, 1.6 or 3.2 mg/mL twice weekly, 4 weeksFaster healing at the two lower strengths; no benefit at 3.2 mg/mL
Mahlapuu et al., 2021, Wound Repair Regen (HEAL LL-37)PubMed 34687253148 people with venous leg ulcersTopical 0.5 or 1.6 mg/mL vs placeboNo significant difference in healing overall; possible benefit in large ulcers (post hoc)
What we don’t know yet
  • Human trials were topical, not injected.
  • The larger phase 2b trial did not meet its main goal.
  • Ben Greenfield warns of a die-off reaction in people with SIBO; see his quote.
  • Grey-market products are unregulated, so identity, purity and dose accuracy vary.
Common questions

Has LL-37 been tested by injection?

Not in the trials we found. Both human trials applied it to leg ulcers.

Why does the protocol section only contain quotes?

We do not write our own dose ranges. The protocol cards show, word for word, what named people have publicly said, with their caveats and a link to the source.

About this page

Word-for-word statements about LL-37, a human antimicrobial peptide, each with a link to the source. The wound-healing trials are listed separately as context.

Also known as
Cathelicidin antimicrobial peptide (CAMP), human
Type
37-amino-acid human antimicrobial peptide
Last updated
11 Oct 2026

Last reviewed 11 Oct 2026 · Compiled by the Peptide Dosing editorial team · How we check quotes