LL-37: research

LL-37 dosage

Typical reported dose: 100–125 mcg once a day

• First wound trial: 0.5 mg/mL: 0.5 mg/mL LL-37 applied to the ulcer twice weekly for 4 weeks. twice weekly, on the skin. Studied in a trial. Studied in: Adults with hard-to-heal venous leg ulcers. (source)
• First wound trial: 1.6 mg/mL: 1.6 mg/mL LL-37 applied to the ulcer twice weekly for 4 weeks. twice weekly, on the skin. Studied in a trial. Studied in: Adults with hard-to-heal venous leg ulcers. (source)
• First wound trial: 3.2 mg/mL: 3.2 mg/mL LL-37 applied to the ulcer twice weekly for 4 weeks. twice weekly, on the skin. Studied in a trial. Studied in: Adults with hard-to-heal venous leg ulcers. (source)
• HEAL: 0.5 mg/mL: 0.5 mg/mL at 25 microlitres/cm², giving 12.5 mcg/cm² per application. twice weekly, every 3 ± 1 days, on the skin. Studied in a trial. Studied in: Adults with hard-to-heal venous ulcers receiving compression. (source)
• HEAL: 1.6 mg/mL: 1.6 mg/mL at 25 microlitres/cm², giving 40 mcg/cm² per application. twice weekly, every 3 ± 1 days, on the skin. Studied in a trial. Studied in: Adults with hard-to-heal venous ulcers receiving compression. (source)
• Foot-ulcer cream: 0.5 mg/g: 0.5 mg/g cream; 0.025 mL cream/cm² of wound, twice weekly for 4 weeks. twice weekly, on the skin. Studied in a trial. Studied in: Adults with mildly infected diabetic foot ulcers. (source)

These are doses reported in labels, trials or user reports, not a personal plan. Check the source behind each one.

Work out syringe units with the dosing calculator

LL-37 side effects and risks

Reported side effects

• Redness, swelling or irritation around ulcers: Pooled across all arms: ulcer redness 42.6%, swelling 39.2%; nearby skin redness 54.1%. No consistent excess versus placebo., mild. Assess local changes at each dressing change. (source)
• Adverse events during topical treatment: Any event: 20/48 at 0.5 mg/mL, 24/49 at 1.6 mg/mL, 20/51 placebo. These are not all drug caused., moderate. Review new symptoms; topical trial results do not describe injected-product safety. (source)
• Serious events during topical study: 11/148, 7.4%, across all arms. None was judged related to study drug; no deaths., serious. Seek urgent assessment of serious symptoms. (source)
• Irritant dermatitis in foot-ulcer trial: 1/13 active participants; attributed to excess wound fluid rather than LL 37 itself., mild. Have wound care reassessed. (source)
• Immune reactions or inflammatory flares: FDA flags immune reaction risk; systemic incidence is unknown. Laboratory work links LL 37 to autoimmune signaling., serious. New rash, swelling or systemic worsening needs assessment. (source)
• Symptoms reported after community use: One user described persistent spinal spasms and dry hair after a 4 week course; causation was not verified., moderate. Obtain assessment rather than using another untested peptide to reverse symptoms. (source)

Stop and get help if

• Breathing trouble, tongue or throat swelling, or fainting: Stop and get emergency care immediately.
• Spreading hot redness, increasing wound pain or fever: Seek urgent assessment for wound infection; LL-37 is not a proven substitute for infection care.
• New severe symptoms after an injection or rapidly worsening skin disease: Stop and seek prompt medical review; do not assume this is a helpful immune or detox response.

Who should avoid it

• pregnant: Precautionary block. Pregnancy was excluded from human trials; fetal safety is unknown.
• breastfeeding: Precautionary block. Breastfeeding was excluded; infant exposure and effects are unknown.
• tryingToConceive: Sperm-damaging effects occurred in lab and mouse work. Human reproductive risk from dosing is unknown.
• under18: No pediatric dosing or safety regimen established; human dosing studies were in adults.
• activeCancer: Precautionary block outside oncology research. FDA cites tumor-promoting findings in some tissues; LL-37 also promotes vessel growth.
• cancerHistory: Discuss prior cancer with oncology. Effects depend on the tissue and are not established by the three-person melanoma results.
• autoimmuneDisease: LL-37 can drive self-DNA immune signaling. Active autoimmune disease was excluded from the melanoma study.
• immunosuppressed: The melanoma trial excluded immune deficiency and systemic steroids; infection and immune effects remain uncertain.
• kidneyDisease: Human systemic clearance and kidney dose adjustments are unknown; the melanoma trial imposed kidney-function limits.
• liverDisease: No established liver dose adjustment; the melanoma trial required acceptable bilirubin, ALT and AST.
• other: Avoid re-exposure after a serious allergy to LL-37 or its formulation.
• testedAthlete: S0 prohibits unapproved pharmacological substances at all times. Verify status with the relevant anti-doping body.

Interactions

• Systemic steroids and other immunosuppressants: Immune effects may conflict. This is a precaution, not a proven interaction; systemic steroids were excluded from the melanoma trial.
• Other immune-active peptide stacks: No human combination trial found. Duplicate LL-37 exposure and multi-peptide immune effects have no established safety limits.

Product quality risks

• FDA flags immune reactions, peptide impurities and difficulty characterizing the active ingredient.
• Unregulated peptides may contain the wrong amount or ingredient, microbes or endotoxins; these risks lack LL-37-specific market rates.
• Trial material underwent content, impurity and identity testing. A research-vial label does not establish equivalent quality.

How LL-37 works

LL-37 can damage microbial membranes and send signals to immune and skin cells. It can help blood vessels and wound tissue grow in experiments. It can also trigger inflammation, including immune responses to the body's own DNA. Its effects depend on the tissue and concentration.

• Microbial membranes: Disrupts membranes in laboratory studies.
• FPR2 / FPRL1: Signals to immune and vessel-lining cells; promoted new blood vessels in animals.
• Self-DNA and TLR9: Helps self-DNA trigger interferon release in immune cells, a pathway linked to psoriasis.

Half-life: No reliable human elimination half-life for purified LL-37 was identified.