LL-37 Dosage: What's Been Studied

Key takeaways

• No study has ever given LL-37 to people by injection under the skin, so there is no studied dose for the way it is sold. Every subcutaneous LL-37 chart online is a seller's or a forum's invention.
• The human doses that exist are topical: 0.5, 1.6 and 3.2 mg/mL applied twice a week to chronic venous leg ulcers, and a 0.5 mg/g cream applied twice a week to diabetic foot ulcers. In the larger leg-ulcer trial, 12.5 or 40 micrograms per square centimeter twice a week for 13 weeks did no better than placebo overall.
• The only injected human doses were 250 and 500 mcg put directly into each melanoma skin metastasis once a week, in three cancer patients. A patient at the same center developed widespread skin lesions that cleared after the injections stopped.
• Seller charts say 100 to 200 mcg under the skin daily, five days a week. By our arithmetic, that is 500 to 1,000 mcg a week, about as much as or more than the 290 to 930 mcg a week the phase 2b trial applied to an average open ulcer at the start of treatment.
• No US pharmacy may compound LL-37 in October 2026, so this page has no units table and no reconstitution example: there is no labeled product to measure.

The direct answer: there is no LL-37 dose for injection, because no human study has ever injected it under the skin. The doses that have been studied in people were applied to open ulcers, injected into melanoma metastases, or delivered by an engineered gut bacterium, and none of them translates into the 100 to 200 mcg daily injections on seller charts. Our LL-37 profile covers what the peptide does, its risks and its legal status; our LL-37 versus KPV comparison covers the gut and skin question the two are often bought for.

The studied doses

Three things stand out. First, the dose-response ran backward: in the first trial the lowest concentration did best and the highest did nothing, and in the second, 0.5 mg/mL beat 1.6 mg/mL on most measures. Second, every wound dose was measured per square centimeter of open ulcer, not per person, so it has no meaning for an injection. Third, the only injections were into tumors, in patients with metastatic melanoma, under weekly oncology review.

What those doses add up to, labeled as arithmetic

None of the following is a dose. It is here to show the scale of what was studied against what is sold.

• Leg ulcers. At the start of the phase 2b trial, the average ulcer measured 11.6 square centimeters. At 12.5 mcg/cm² that is about 145 mcg per application, and at 40 mcg/cm² about 465 mcg, twice a week: roughly 290 to 930 mcg a week, spread on an open wound. The amount fell as wounds shrank, because it was dosed by area.
• Foot ulcers. At 0.025 mL per square centimeter of a 0.5 mg/g cream, the amount is about 12.5 mcg/cm², the same as the lower leg-ulcer concentration, on wounds with a median area of about 5 cm²: roughly 60 mcg per application.
• Melanoma. 250 mcg into each of two to four lesions is 500 to 1,000 mcg per weekly session; at 500 mcg per lesion, 1,000 to 2,000 mcg.
• Seller charts. 100 to 200 mcg a day for five days is 500 to 1,000 mcg a week, injected into intact tissue; the 500 mcg charts reach 2,500 mcg a week.

So the common chart puts as much or more LL-37 into the body each week as the wound trials put onto a wound, by a route no trial tested, for months in some 'protocols'. It is not a cautious fraction of a studied dose.

The charts sellers circulate

Some charts honestly label their subcutaneous numbers as anecdotal; that does not make them safer, only more candid. We found no seller chart with a nasal dose. Anyone considering LL-37 for sinus problems should know that in mice, LL-37 dripped into the nose is used to create sinonasal inflammation, with more neutrophils and mast cells at higher concentrations (Alt 2015).

Why there is no reconstitution example or units table

People searching for an LL-37 dose usually want one more thing: how much bacteriostatic water to add to a 5 mg vial and how many units to draw. We are not going to give that, for three reasons.

• No pharmacy may make it. LL-37 is not approved, has no USP monograph, is not part of an approved drug and is not on FDA's list of substances 503A pharmacies may compound. It came off FDA's Category 2 list on April 15, 2026 after its nomination was withdrawn and is due for advisory committee review by February 2027, but nothing has been added to the permitted list. The legal tracker records each step.
• The arithmetic would describe an unknown. Units-per-dose math assumes the vial holds what the label says. A research vial's content, purity and sterility have not been verified by anyone.
• Dosing help is what FDA cites. In its 2026 warning letters to research-peptide sellers, FDA pointed to dosing guides, reconstitution calculators and bundled bacteriostatic water as evidence that the vials were drugs for human use.

Our reconstitution calculator and the units converter exist for medications a pharmacy has dispensed with a labeled concentration. LL-37 has neither. Our KPV dosage chart takes the same studied-versus-sold approach to another peptide no pharmacy may compound.

Duration and the skin

The trials ran for four to thirteen weeks of twice-weekly topical treatment, or up to eight weekly tumor injections. No study has tested the months of daily injections some protocols describe. The closest animal evidence is unsettling for anyone injecting LL-37 'for skin': in mice, LL-37 injected into the skin every 12 hours for two days produced rosacea-like lesions that recovered, while 20 days of injections produced lesions with collagen deposition that did not fully recover (Zhang 2023). The LL-37 profile explains the human evidence linking LL-37 to rosacea and psoriasis.

Bottom line

The only honest LL-37 dosage chart has an empty row for subcutaneous injection. Above it sit topical wound concentrations of 0.5 to 3.2 mg/mL, the lowest of which worked best in a small trial and did not beat placebo in a larger one, and 250 to 500 mcg injected weekly into melanoma lesions in three people. The 100 to 200 mcg daily charts match none of them by route, schedule or rationale, and they add up to more peptide each week than the wound trials applied to open ulcers. Until FDA acts, there is no legal LL-37 product, no label and no dose.

Frequently asked questions

+−What is the correct dosage of LL-37?

There is no correct dosage for the way LL-37 is sold, because no study has ever given it to people by injection under the skin. The human doses that exist are topical, 0.5 to 3.2 mg/mL applied to chronic leg ulcers twice a week and a 0.5 mg/g cream on diabetic foot ulcers twice a week, and 250 to 500 mcg injected weekly into melanoma metastases in three cancer patients. Seller charts of 100 to 200 mcg a day come from none of these.

+−How much LL-37 was used in the leg-ulcer trials?

The first trial applied 0.5, 1.6 or 3.2 mg/mL twice a week for four weeks to venous leg ulcers in 34 patients; the two lower concentrations sped healing and the highest did not. The phase 2b trial applied 0.5 or 1.6 mg/mL at 25 microliters per square centimeter of ulcer, which is 12.5 or 40 micrograms per square centimeter, twice a week for 13 weeks in 148 patients, and found no overall benefit over placebo.

+−How much LL-37 do people inject?

Seller and forum charts list 100 to 200 mcg under the skin once a day, often five days on and two off, in blocks of two to four weeks, with some charts going to 250 or 500 mcg. No human study supports any of it: the only injected human doses were 250 and 500 mcg put directly into melanoma skin metastases once a week, in three patients under oncology monitoring, and one of the center's patients developed widespread skin lesions.

+−How do you reconstitute a 5 mg vial of LL-37?

We do not give reconstitution instructions for LL-37. No US pharmacy may compound it in 2026, so a 5 mg vial is a research product whose content, purity and sterility nobody has verified, and FDA's 2026 warning letters treated reconstitution guides and bundled bacteriostatic water on vendor sites as evidence that such vials are unapproved drugs for human use. The arithmetic would be precise about an unknown amount of an unknown substance.

+−Is there an oral or nasal LL-37 dose?

Not for the synthetic peptide. The trial described as 'oral LL-37' gave hospitalized COVID-19 patients a genetically engineered Lactococcus lactis bacterium that produces LL-37 in the gut, and its abstract does not state the amount. No study has tested an LL-37 nasal spray in people; in mice, LL-37 dripped into the nose is used to create sinus inflammation, with more inflammation at higher concentrations.

+−How long should you take LL-37?

No study has defined a course for anything other than wounds and tumors: four or thirteen weeks of twice-weekly topical applications to leg ulcers, four weeks of cream on foot ulcers, and up to eight weekly injections into melanoma lesions. The 'two to four weeks on, two weeks off' cycles on seller charts have no study behind them. In mice, twice-daily skin injections for 20 days produced rosacea-like lesions that did not fully recover.

+−Can a doctor prescribe LL-37 at a proper dose?

Not in October 2026. LL-37 is not FDA-approved and no US pharmacy may compound it: it came off FDA's Category 2 list on April 15, 2026 after its nomination was withdrawn and is due for advisory committee review by February 2027, but it is not on the permitted list. With no pharmacy label, there is no labeled dose for any provider to follow.

Sources

1. StudyGrönberg A, Mahlapuu M, Ståhle M, Whately-Smith C, Rollman O. Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial. Wound Repair Regen 2014;22:613-21. (2014)
2. StudyMahlapuu M et al. Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: a multicentric prospective randomized placebo-controlled clinical trial. Wound Repair Regen 2021;29:938-50. (2021)
3. StudyMiranda E et al. Efficacy of LL-37 cream in enhancing healing of diabetic foot ulcer: a randomized double-blind controlled trial. Arch Dermatol Res 2023;315:2623-33. (2023)
4. StudyM.D. Anderson Cancer Center. Intratumoral injections of LL37 for melanoma (NCT02225366), phase 1/2; record with results posted December 9, 2021. ClinicalTrials.gov. (2021)
5. StudyDolkar T et al. Dermatologic toxicity from novel therapy using antimicrobial peptide LL-37 in melanoma: a detailed examination of the clinicopathologic features. J Cutan Pathol 2018;45:539-44. (2018)
6. StudyZhao Y et al. Efficacy and safety of oral LL-37 against the Omicron BA.5.1.3 variant of SARS-CoV-2: a randomized trial. J Med Virol 2023;95:e29035. (2023)
7. StudyZhang C et al. Long-term administration of LL-37 can induce irreversible rosacea-like lesion. Curr Issues Mol Biol 2023;45:2703-16. (2023)
8. StudyAlt JA et al. Topical cathelicidin (LL-37) an innate immune peptide induces acute olfactory epithelium inflammation in a mouse model. Int Forum Allergy Rhinol 2015;5:1141-50. (2015)