LL-37 Side Effects: What Studies and Users Report
What FDA labels and clinical studies report for LL-37, how strong that evidence is, and what is still unknown.
Side effects reported in studies
Side effects reported in published studies, strongest design first. Frequencies are quoted as the source gives them; animal results are labelled.
| Side effect | How common | Study type | Source |
|---|---|---|---|
| Tolerability“The study drug was well tolerated and safe in both dose strengths.” | Frequency not stated | Human RCTn = 148 | Wound repair and regeneration 2021, PMID 34687253 |
| Local or systemic adverse events“There were no safety concerns regarding local or systemic adverse events.” | Frequency not stated | Human RCTn = 34 | Wound repair and regeneration 2014, PMID 25041740 |
What is not known
- How common each effect is at the doses people use outside of studies.
- Effects that take longer to appear than the length of the published studies.
- How LL-37 interacts with other medicines and supplements.
- Whether research-grade products, which are not checked by the FDA, behave like the material used in studies.
When to get medical help
Get urgent care for: trouble breathing, swelling of the face or throat, a widespread rash, severe or lasting stomach pain, fainting, or an injection site that becomes hot, red and spreading.
This is not a complete list. A doctor or pharmacist can help you judge whether a symptom is related.
Common questions
What are the side effects of LL-37?
Studies we summarise reported tolerability, local or systemic adverse events. The table on this page gives how often each happened and links each source.
Is LL-37 safe?
Its safety has not been established by an FDA review. LL-37 is not FDA approved for any use. Research-chemical products are not checked for purity or dose.
More on LL-37
Sources
- 1Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: A multicentric prospective randomized placebo-controlled clinical trial.Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society · 2021PMID 34687253Accessed 2 Oct 2026
- 2Treatment 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 and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society · 2014PMID 25041740Accessed 2 Oct 2026
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