LL-37, also called cathelicidin LL-37, is a human antimicrobial peptide studied in innate immunity, skin disease, infections, and wound healing. Human randomized trials exist, including venous leg ulcer studies, but that does not mean LL-37 is proven or appropriate for self-use. Chia does not currently offer LL-37.
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See if you qualify →What it is
LL-37 is a human antimicrobial peptide, meaning a short protein-like molecule that helps the body respond to microbes as part of innate immunity. It is commonly discussed as cathelicidin LL-37, human cathelicidin antimicrobial peptide, cathelicidin antimicrobial peptide 18, or CAMP in research on skin, infection, and inflammation 2 4.
In plain English: LL-37 is one of the body's built-in defense signals. It has been studied in human skin commensal bacteria and Staphylococcus aureus research, atopic dermatitis, pulmonary infectious diseases, active tuberculosis, chronic rhinosinusitis with nasal polyps, and wound research 2 3 4 6 8 9.
Patients often find LL-37 while also reading about other peptides such as KPV, BPC-157, and TB-500. Those compounds are different substances with different evidence questions, so they should not be treated as interchangeable.
| Name you may see | What it means | Why it matters |
|---|---|---|
| LL-37 | The peptide form often discussed in immune and wound research | Most consumer searches use this name. |
| Cathelicidin LL-37 | A member of the cathelicidin antimicrobial peptide family | This is the more scientific name used in many papers. |
| Human cathelicidin antimicrobial peptide / CAMP | Related naming for the human cathelicidin pathway | Vitamin D and biomarker studies may use these terms 10. |
| Antimicrobial peptide | A small immune-defense peptide active in host defense research | This class includes several molecules studied in skin, mucosa, and infection contexts 1 12. |
Mechanism of action
LL-37 appears to sit at the crossroads of antimicrobial defense and immune signaling. Human studies support discussion of antimicrobial peptide biology in skin, saliva, airways, wounds, and infection-related biomarker research, but not every proposed pathway has been proven to translate into a treatment effect for patients 1 2 4 8.
Innate immune signaling and antimicrobial activity
Innate immunity is the fast, first-line part of the immune system. LL-37 is studied as part of that system because antimicrobial peptides can interact with microbes and immune cells; in human skin research, antimicrobials from skin commensal bacteria were studied in relation to Staphylococcus aureus and atopic dermatitis 2.
LL-37-related biology is not static. A randomized controlled trial examined acute salivary antimicrobial peptide secretion responses to different exercise intensities and durations, showing that researchers study these peptides as dynamic immune markers in humans 1.
Inflammation, skin barrier, and wound-healing pathways
In skin and wound research, LL-37 is discussed because antimicrobial defense, inflammation, and tissue repair can overlap. Randomized placebo-controlled studies evaluated LL-37 in hard-to-heal venous leg ulcers, but those trials do not make LL-37 a general wound self-care product 5 9.
In airway research, LL-37 has been linked with neutrophil extracellular trap formation in chronic rhinosinusitis with nasal polyps. That supports a mechanism discussion, but it does not prove that taking LL-37 improves sinus disease 8.
Vitamin D is another related pathway. A clinical study reported vitamin D3 induction of human cathelicidin antimicrobial peptide 18 in newborns, and a randomized trial studied weekly vitamin D supplementation in pediatric atopic dermatitis with type 2 immunity biomarkers 3 10.
Evidence
LL-37 has an assigned evidence grade of A because the retrieved PubMed set includes two or more human randomized controlled trials. That is a design-and-quantity grade, not a claim that LL-37 is proven, broadly safe, or appropriate for personal use 1 5 9.
The strongest human study cluster in the retrieved set is wound research. LL-37 was evaluated in randomized placebo-controlled trials for hard-to-heal venous leg ulcers, including a multicenter prospective trial and an earlier randomized placebo-controlled trial 5 9.
Other human studies are more about biology, biomarkers, or related pathways than direct patient use. Examples include circulating LL-37 in pulmonary infectious diseases, serum LL-37 in active tuberculosis and other infectious diseases, antimicrobial peptide biomarkers in joint infection research, and LL-37 in chronic rhinosinusitis with nasal polyps 4 6 8 12.
Skin studies also matter, but they answer narrow questions. Human clinical research has examined antimicrobials from skin commensal bacteria in relation to Staphylococcus aureus and atopic dermatitis, while a pediatric randomized trial studied vitamin D supplementation and atopic dermatitis biomarkers 2 3.
| Research area | Human evidence in the retrieved set | What it can tell us | What it cannot tell us |
|---|---|---|---|
| Hard-to-heal venous leg ulcers | Randomized placebo-controlled trials 5 9 | LL-37 has been formally evaluated in a wound-healing trial setting. | It does not establish self-use, general wound care use, or dosing for an individual patient. |
| Atopic dermatitis and skin microbes | Human clinical and randomized biomarker studies 2 3 | LL-37-related antimicrobial pathways are relevant to skin research. | It does not prove that LL-37 improves atopic dermatitis symptoms. |
| Pulmonary infection and tuberculosis | Human clinical and randomized records measuring LL-37 levels 4 6 | LL-37 can be studied as a biomarker in infectious-disease settings. | It does not prove LL-37 is an infection treatment. |
| Chronic rhinosinusitis with nasal polyps | Human clinical study of neutrophil extracellular trap formation 8 | It supports a mechanism discussion about inflammation. | It does not prove symptom improvement from LL-37 use. |
| Exercise and salivary antimicrobial peptides | Randomized controlled trial of exercise intensity and duration 1 | Antimicrobial peptide secretion can be studied as a short-term human response. | It does not establish LL-37 supplementation or peptide therapy outcomes. |
What studies exist
| Year | Design | Study | Journal | Record |
|---|---|---|---|---|
| 2024 | Randomised controlled trial | Acute salivary antimicrobial peptide secretion response to different exercise intensities and durations | American journal of physiology. Regulatory, integrative and comparative physiology | PMID 39155711 |
| 2017 | Clinical trial | Antimicrobials from human skin commensal bacteria protect against Staphylococcus aureus and are deficient in atopic dermatitis | Science translational medicine | PMID 28228596 |
| 2024 | Randomised controlled trial | Effect of weekly vitamin D supplementation on the severity of atopic dermatitis and type 2 immunity biomarkers in children: A randomized controlled trial | Journal of the European Academy of Dermatology and Venereology : JEADV | PMID 38483248 |
| 2017 | Clinical trial | Circulating cathelicidin LL-37 in adult patients with pulmonary infectious diseases | Clinical and investigative medicine. Medecine clinique et experimentale | PMID 28218580 |
| 2021 | Randomised controlled trial | Evaluation 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 | PMID 34687253 |
| 2017 | Randomised controlled trial | Serum level of cathelicidin LL-37 in patients with active tuberculosis and other infectious diseases | Journal of biological regulators and homeostatic agents | PMID 28956425 |
| 2020 | Randomised controlled trial | The therapeutic efficacy of Bifidobacterium animalis subsp. lactis BB-12(®) in infant colic: A randomised, double blind, placebo-controlled trial | Alimentary pharmacology & therapeutics | PMID 31797399 |
| 2019 | Clinical trial | LL-37 promotes neutrophil extracellular trap formation in chronic rhinosinusitis with nasal polyps | Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology | PMID 31046155 |
| 2014 | Randomised controlled trial | 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 and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society | PMID 25041740 |
| 2009 | Clinical trial | Vitamin D(3) induces expression of human cathelicidin antimicrobial peptide 18 in newborns | International journal of hematology | PMID 19943126 |
| 2015 | Clinical trial | Diagnostic value of anti-microbial peptide, cathelicidin in congenital pneumonia | The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians | PMID 25354286 |
| 2020 | Clinical trial | Antimicrobial peptides in human synovial membrane as (low-grade) periprosthetic joint infection biomarkers | European journal of medical research | PMID 32799924 |
| Registration | Phase | Status | Enrolment | Title |
|---|---|---|---|---|
| NCT03923218 | N/A | COMPLETED | 60 | Effects of Smoking and Vitamin D3 on the Levels of Human Cathelicidin Peptide LL-37 |
| NCT04404335 | N/A | COMPLETED | 60 | The Role of Anti-inflammatory Cytokines and Antimicrobial Peptide LL-37 Biomarkers in the Treatment of Periodontal Disease. |
| NCT04098562 | PHASE2 | UNKNOWN | 40 | Efficacy of LL-37 Cream on Bacteria Colonization, Inflammation Response and Healing Rate of Diabetic Foot Ulcers |
| NCT01398280 | EARLY_PHASE1 | COMPLETED | 15 | Effects of Aminocaproic Acid (ACA) on Rosacea-specific Inflammation |
| NCT05054361 | N/A | RECRUITING | 180 | Crosstalk Between Mucosal-Associated Invariant T (MAIT) Cells and the Gut Microbiota and Mucosa in the Development of Type 1 Diabetes in Children |
| NCT03639376 | N/A | COMPLETED | 180 | Passive Smoking and LL-37 in Children |
| NCT01372995 | PHASE2 | COMPLETED | 31 | Vitamin D in Ventilated ICU Patients |
| NCT04292548 | N/A | COMPLETED | 180 | Salivary TAS, TOS, LL-37 and Dental Status in Passive Smoking Children |
This table is retrieved from PubMed and ClinicalTrials.gov rather than assembled by hand, so it shows what is indexed — including the absences. Last retrieved 2026-09-11.
Reported dosing ranges
No patient dosing range for LL-37 can be inferred from the retrieved records. The available records identify human research settings, including venous leg ulcer trials and biomarker studies, but the citation set provided here does not supply enough dosing detail to turn into personal instructions 5 9.
This distinction matters. A dose used in a controlled research protocol is not the same as a clinician choosing whether a substance fits a specific patient, wound, infection history, medication list, immune condition, or pregnancy status.
| Source | Studied context | Dose information available from the retrieved record | How to interpret it |
|---|---|---|---|
| Mahlapuu et al., 2021 5 | Multicenter prospective randomized placebo-controlled clinical trial in hard-to-heal venous leg ulcers | The retrieved citation record does not provide a patient dosing range. | Research context only; not a dosing recommendation. |
| Grönberg et al., 2014 9 | Randomized placebo-controlled clinical trial in hard-to-heal venous leg ulcers | The retrieved citation record does not provide a patient dosing range. | Research context only; not a dosing recommendation. |
| Cao et al., 2019 8 | Chronic rhinosinusitis with nasal polyps and neutrophil extracellular trap formation | No patient dosing range is provided in the retrieved citation record. | Mechanism research; not a use protocol. |
| Majewski et al., 2017 pulmonary infectious diseases 4 | Circulating LL-37 in adult pulmonary infectious diseases | No patient dosing range is provided in the retrieved citation record. | Biomarker context; not treatment dosing. |
| Misawa et al., 2009 10 | Vitamin D3 induction of human cathelicidin antimicrobial peptide 18 in newborns | This is vitamin D3/CAMP biology, not an LL-37 dosing record. | Related pathway evidence; not LL-37 dosing. |
Legal status
Our regulatory log holds no confirmed federal action for LL-37. That means we have not found one with a primary source — not that none exists.
This section is generated from a dated log of federal actions rather than written by hand, and it is re-checked daily against the Federal Register and FDA sources. Last checked 2026-09-11. See the full legal-status tracker for every compound we follow.
Safety
LL-37 safety is not settled for general patient use. The retrieved human records include randomized wound trials that evaluated LL-37 in controlled settings, but the records provided here do not give a full adverse-event profile that can be applied to self-use 5 9.
The main safety lesson is not that LL-37 is harmless. It is that controlled studies, biomarker studies, and real-world self-use are different. A wound trial population is not the same as a person buying a vial online without diagnosis, sterility checks, follow-up, or clinician oversight.
Human studies in infection-related settings show why clinician context matters. LL-37 levels have been studied in pulmonary infectious diseases, active tuberculosis, congenital pneumonia, and joint infection biomarker research; these are medical settings where symptoms can reflect serious disease 4 6 11 12.
- Possible concern: local irritation or wound-site issues may matter in skin or wound contexts, but the retrieved records do not provide a complete side-effect list that applies to consumers 5 9.
- Possible concern: immune and inflammatory conditions may change the risk-benefit discussion, because LL-37 is studied in immune signaling and inflammatory pathways 3 8.
- Possible concern: active infection, chronic wounds, or possible tuberculosis require medical evaluation, not peptide self-experimentation 4 6.
- Supply concern: products sold as “research use only” are not medical care. They may raise risks around sterility, identity, impurities, storage, and dosing accuracy.
If your interest in LL-37 is skin-related, you may also be comparing it with better-known skin and antioxidant topics such as GHK-Cu or glutathione. Those are separate substances with separate evidence and safety profiles.
Interactions
No dedicated LL-37 drug-interaction study is included in the retrieved evidence set. That is not reassurance; it means interaction risk is uncertain from the records available here.
Patients should be especially careful if they have immune disease, active infection, chronic wounds, dermatologic disease, chronic sinus disease, lung infection symptoms, or a history of tuberculosis, because LL-37 appears in human studies involving immune, infectious, airway, and wound contexts 4 6 8 9.
Pregnancy, breastfeeding, and pediatric use need extra caution. The retrieved records include newborn and child studies related to cathelicidin biology or atopic dermatitis biomarkers, but those do not establish that LL-37 use is appropriate during pregnancy, breastfeeding, or childhood 3 10 11.
| Question to ask a clinician | Why it matters |
|---|---|
| Do I have an active infection or wound that needs diagnosis first? | LL-37 has been studied in infection and wound contexts, where missing the underlying diagnosis can be risky 4 5. |
| Could my immune condition change the risk discussion? | LL-37 is tied to innate immune and inflammatory pathways in human research 2 8. |
| Are my medications relevant? | The retrieved evidence set does not include dedicated interaction studies, so medication review should be individualized. |
| Am I pregnant, breastfeeding, or asking for a child? | The retrieved child and newborn records are research contexts, not self-use guidance 3 10 11. |
How to obtain it legally
Chia does not currently offer LL-37. We are saying that plainly because a useful peptide reference should separate education from access. We should not imply that we prescribe, compound, sell, or ship a compound that is not in our live catalog.
A safer process for any peptide starts with a licensed clinician evaluation. That means a clinician reviews the reason you are asking, your diagnosis or symptoms, your medication list, allergies, immune history, pregnancy or breastfeeding status, and whether your goal matches any reasonable medical pathway.
If a treatment is clinically appropriate and properly sourced, a prescription decision belongs to the clinician. A licensed pharmacy is different from a research-chemical vendor: pharmacies operate under pharmacy standards, while “research use only” sellers are not providing diagnosis, follow-up, sterile-use counseling, or ongoing medical care.
At Chia, our available care is limited to treatments in our current catalog. For example, we offer clinician-reviewed online care for Sermorelin, NAD+, glutathione, GHK-Cu cream, compounded semaglutide, and compounded tirzepatide where clinically appropriate. We do not offer LL-37.
For Chia treatments that are offered, the process is 100% online: a health questionnaire, review by a licensed US provider, provider-guided dosing when prescribed, dispensing through state-licensed US 503A compounding pharmacies, and home delivery. A prescription requires a medical evaluation and is not guaranteed; compounded drugs are not FDA-approved.
FAQ
LL-37 is a human antimicrobial peptide involved in innate immune defense. Human studies have looked at LL-37-related biology in skin, wound, infection, airway, vitamin D, and exercise-response contexts. That does not mean LL-37 is proven for self-use.
LL-37 has been studied in human trials, including wound-healing research, but the retrieved records do not establish a complete safety profile for general use. Safety depends on the person, the medical problem, the source, the formulation, and clinician follow-up.
The retrieved citation records do not provide a complete consumer side-effect list. Possible concerns include local skin or wound reactions, immune or inflammatory effects, and risks from unregulated products such as sterility, identity, impurity, and dosing problems.
LL-37 is assigned evidence grade A because the retrieved PubMed set includes two or more human randomized controlled trials. The grade describes the amount and design of evidence, not whether LL-37 works or is safe.
LL-37 has been evaluated in randomized placebo-controlled studies of hard-to-heal venous leg ulcers. Those studies are important, but they do not make LL-37 a general wound-care product or a self-treatment plan.
No. Vitamin D is a hormone-like vitamin, while LL-37 is an antimicrobial peptide. Some human research connects vitamin D biology with cathelicidin antimicrobial peptide pathways, but they are not the same substance.
Chia does not currently offer LL-37. If you are considering any peptide, avoid treating research-chemical vendors as medical care. A safer process starts with a licensed clinician evaluation and a pharmacy pathway when a treatment is clinically appropriate.
No. Chia does not currently offer LL-37. We do offer other clinician-reviewed treatments in our live catalog, but this page is educational only for LL-37.
References
- 1.PMID 39155711 [randomised controlled trial] Ito R, Uchino T, Uchida M, et al. Acute salivary antimicrobial peptide secretion response to different exercise intensities and durations. American journal of physiology. Regulatory, integrative and comparative physiology. 2024.
- 2.PMID 28228596 [clinical trial] Nakatsuji T, Chen TH, Narala S, et al. Antimicrobials from human skin commensal bacteria protect against Staphylococcus aureus and are deficient in atopic dermatitis. Science translational medicine. 2017.
- 3.PMID 38483248 [randomised controlled trial] Borzutzky A, Iturriaga C, Pérez-Mateluna G, et al. Effect of weekly vitamin D supplementation on the severity of atopic dermatitis and type 2 immunity biomarkers in children: A randomized controlled trial. Journal of the European Academy of Dermatology and Venereology : JEADV. 2024.
- 4.PMID 28218580 [clinical trial] Majewski K, Żelechowska P, Brzezińska-Błaszczyk E. Circulating cathelicidin LL-37 in adult patients with pulmonary infectious diseases. Clinical and investigative medicine. Medecine clinique et experimentale. 2017.
- 5.PMID 34687253 [randomised controlled trial] Mahlapuu M, Sidorowicz A, Mikosinski J, 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 and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society. 2021.
- 6.PMID 28956425 [randomised controlled trial] Majewski K, Agier J, Kozłowska E, et al. Serum level of cathelicidin LL-37 in patients with active tuberculosis and other infectious diseases. Journal of biological regulators and homeostatic agents. 2017.
- 7.PMID 31797399 [randomised controlled trial] Nocerino R, De Filippis F, Cecere G, et al. The therapeutic efficacy of Bifidobacterium animalis subsp. lactis BB-12(®) in infant colic: A randomised, double blind, placebo-controlled trial. Alimentary pharmacology & therapeutics. 2020.
- 8.PMID 31046155 [clinical trial] Cao Y, Chen F, Sun Y, et al. LL-37 promotes neutrophil extracellular trap formation in chronic rhinosinusitis with nasal polyps. Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology. 2019.
- 9.PMID 25041740 [randomised controlled trial] Grönberg A, Mahlapuu M, Ståhle M, et al. 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 and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society. 2014.
- 10.PMID 19943126 [clinical trial] Misawa Y, Baba A, Ito S, et al. Vitamin D(3) induces expression of human cathelicidin antimicrobial peptide 18 in newborns. International journal of hematology. 2009.
- 11.PMID 25354286 [clinical trial] Gad GI, Abushady NM, Fathi MS, et al. Diagnostic value of anti-microbial peptide, cathelicidin in congenital pneumonia. The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatology Societies, the International Society of Perinatologists. 2015.
- 12.PMID 32799924 [clinical trial] Banke IJ, Stade N, Prodinger PM, et al. Antimicrobial peptides in human synovial membrane as (low-grade) periprosthetic joint infection biomarkers. European journal of medical research. 2020.
About this article
Chia Health Editorial Team — Evidence-reviewed health education
This article is for educational purposes only and is not a substitute for individualized medical advice. Talk to a licensed clinician before starting, stopping, or changing any prescription.
AI tools may assist with research and drafting. Chia's editorial team reviews source use, clarity, treatment information, and safety framing before publication. A clinician is named only after explicit sign-off. Read our editorial standards.
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