Chronic wound healing
Topical wound repair is the clearest clinical-development area.
Explore the research →HOST-DEFENCE & WOUND RESEARCH
LL-37
Produced naturally by the body, LL-37 forms part of our defences and is being explored for antimicrobial activity, inflammation and wound healing.
Wound healingAntimicrobial defenceInnate immunity
Small topical human trials; systemic use remains experimentalTopical LL-37 has entered randomized wound trials, including a positive small venous-ulcer study, but dose-response was not simply 'more is better' and injectable use lacks comparable evidence.
FOLLOW THE FULL PICTUREFrom interest to evidence, quality and the numbers.
Where does LL-37 research look most promising?
LL-37 is part of the body's own first line of defence, which makes its appeal unusually intuitive. It is linked with antimicrobial activity, immune signalling and tissue repair, bringing infection defence, inflammation and wound healing into the same research story.
Antimicrobial defence
LL-37 can act against a range of microbes in laboratory systems.
Explore the research →Cell migration & repair
LL-37 influences keratinocytes, endothelial cells and repair signalling.
Explore the research →THE SCIENCE BIT
A natural defence peptide that meets microbes directly.
LL-37 is part of the body's cathelicidin defence system. Its charge and structure allow it to interact with microbial membranes, which helps explain antimicrobial activity seen in experiments.
It also influences host-cell signalling and inflammation. These roles can differ with concentration and tissue, so antimicrobial activity is not the same as a universal infection treatment.
See the studies & trials →- Microbial membranes
- Direct peptide interactions
- Host-cell signals
- Immune and migration responses
- Local context
- Concentration and tissue matter
How this connects to the research
Natural defence biology with limited, route-specific human treatment evidence.
FROM MOLECULE TO TISSUE
Where LL-37 connects with the body
These are the tissues and biological systems behind the interest in LL-37.
- Skin and wounds
- Topical clinical research.
- Epithelial barriers
- Natural defence biology.
- Immune cells
- Inflammatory communication.
The research behind the interest
Chronic wound healing
Topical wound repair is the clearest clinical-development area.
A first-in-man trial reported faster healing at 0.5 and 1.6 mg/mL. The larger phase IIb trial was neutral overall, with an exploratory signal in larger ulcers.
Mixed human trial evidenceExplore the studies →Antimicrobial defence
LL-37 can act against a range of microbes in laboratory systems.
Laboratory antimicrobial activity does not establish that systemic dosing treats human infection.
Strong mechanistic evidenceExplore the studies →Cell migration & repair
LL-37 influences keratinocytes, endothelial cells and repair signalling.
Preclinical work supports re-epithelialisation and wound-environment effects.
Preclinical + human wound contextExplore the studies →Immune signalling
LL-37 can recruit and modify immune-cell responses.
The same context-dependent biology may support defence or contribute to inflammatory disease.
Complex mechanistic evidenceExplore the studies →Studies & trials
Studies & trials
Original publication · PubMed · trial registry where availableLL-37 in hard-to-heal venous leg ulcers ↗
34 people with hard-to-heal venous leg ulcers
Topical creamTwice weekly3-week run-in, 4-week treatment
Healing-rate constants were approximately six- and three-fold higher than placebo at 0.5 and 1.6 mg/mL; mean ulcer area fell 68% and 50%.
The 3.2 mg/mL arm did not outperform placebo, supporting a non-linear concentration response.
HEAL LL-37 phase IIb venous-leg-ulcer study ↗
148 people with hard-to-heal venous leg ulcers
Topical cream with compressionTwice weekly13-week treatment plus 4-month follow-up
Neither 0.5 nor 1.6 mg/mL significantly improved healing in the full cohort compared with placebo.
A post-hoc subgroup with ulcers at least 10 cm² showed a signal; both strengths were reported as well tolerated.
Evidence snapshot
Evidence snapshot
Separate dimensions, not one overall score◎
Human evidenceLimited
2/5 evidence depth
Small randomized topical wound trials provide direct human evidence.
✓
Clinical efficacyLimited
2/5 evidence depth
Clinical efficacy is not established across wound types, infections or systemic use.
◇
Safety evidenceLimited
2/5 evidence depth
Topical trial safety data exist, but systemic and long-term safety are uncertain.
⌁
Preclinical evidenceStrong
4/5 evidence depth
A large mechanistic literature covers antimicrobial, immune and repair effects.
HOW TO READ THESE SCORESStrong preclinical evidence · limited human evidence
These are editorial evidence-depth ratings on a 1–5 scale, not a statistical result or a single scientific formula. They summarise how much relevant evidence is present in each separate category and how mature that evidence is.
Human evidenceHow much direct research in people is available and how developed it is.
Clinical efficacyWhether human studies demonstrate meaningful outcomes for the claims being discussed.
Safety evidenceHow much human safety, tolerability and longer-term follow-up information is available.
Preclinical evidenceThe depth of laboratory and animal research supporting biological plausibility.
EVIDENCE LANDSCAPELL-37Mechanism → measured response → clinical outcome
Two topical venous-ulcer trials; phase IIb neutral overall
Extensive antimicrobial, barrier and immune biology
No validated systemic dose, efficacy or long-term safety
Keep route, study setting and outcome together
A measured biological response can be valuable evidence without establishing a self-administered protocol or a durable treatment benefit.
From promising signals to human evidencePreclinical research can reveal promising biological signals. Human studies show how far those signals have translated into real-world outcomes.
What people are exploring
COMMUNITY · USE CASES & EXPERIENCE
What people want to change with LL-37
Interest centres on chronic infections, immune resilience and wound repair. The most credible positive human signal is topical wound research, not systemic self-treatment.
Explore the everyday goalsConceptual scientific illustration
THE PRACTICAL ATTRACTION
The goals behind the interest
What the desired change means in daily life, and what makes an experience useful to understand.
Repair of difficult wounds
Topical wound research attracts interest in ulcers or skin that is slow to heal. The meaningful outcome is objective wound progress within a defined care setting, rather than a general feeling of improved immunity.
- What makes a report informative
- Wound measurements and the complete wound-care context.
- What can muddy the picture
- Dressings, circulation, infection treatment and clinical care strongly affect healing.
Persistent infection and biofilm questions
Its antimicrobial biology attracts people looking for answers to recurring or poorly explained symptoms. Laboratory activity against microbes is a research lead, rather than proof of a systemic infection treatment.
- What makes a report informative
- The identified organism, diagnosis and route studied.
- What can muddy the picture
- A laboratory antimicrobial effect cannot establish an effective or safe systemic exposure.
Immune and inflammatory balance
Interest also concerns host defence and inflammatory signalling. LL-37 can influence both, making the idea of simply boosting immunity too narrow to explain its biology.
- What makes a report informative
- A specific clinical outcome rather than a generic immune claim.
- What can muddy the picture
- Topical trial findings do not establish benefit for self-directed injected use.
PUT THE EXPERIENCE IN CONTEXT
How the goals compare with the research
Open an area to distinguish human findings from laboratory explanations.
Chronic wound healing
The published topical trial is often cited as proof of broad healing potential.
Human findings & limits
Small randomized venous-ulcer studies provide a genuine early clinical signal.
Laboratory & animal context
Keratinocyte migration, angiogenesis and antimicrobial research support the wound rationale.
What this means: Promising for a specific topical setting, not proof for all wounds or routes.
Antimicrobial or biofilm support
People discuss LL-37 for persistent infections and biofilms.
Human findings & limits
No general systemic infection indication or validated injectable protocol is established.
Laboratory & animal context
Direct antimicrobial and immune-modulating activity is well documented in laboratory systems.
What this means: Strong biology; clinical treatment claims remain unproven.
Immune support
Its endogenous host-defence role is often simplified into an immune-boosting claim.
Human findings & limits
Endogenous function does not show that more LL-37 improves outcomes.
Laboratory & animal context
Effects can be protective or pro-inflammatory depending on tissue and concentration.
What this means: Context matters; 'more' is not necessarily better.
Route and concentration
Topical, nasal and injected descriptions are often discussed as if they were interchangeable.
Human findings & limits
The direct human evidence is limited to formulated topical wound treatment with compression care.
Laboratory & animal context
Exposure, tissue concentration and inflammatory effects change with route and formulation.
What this means: A topical trial cannot validate systemic self-administration.
Research sources and further reading
Dose & duration
DOSE & DURATION
Research protocols · community patterns · calculator toolsSee the numbers in their proper context
See the amount, how often it was used and how long each study ran. Published human research and community descriptions each carry their own source label, so you can see where the numbers came from.
Source matters. The figures below show authorised, human-research or community-described protocols in their original context — not a personalised recommendation.
ONE ANECDOTAL COMMUNITY EXAMPLE
ANECDOTAL · UNVALIDATEDA cautious systemic example kept apart from topical wound trials
The example below reflects recurring community discussion about injected LL-37. The human studies used formulated topical cream on ulcers with compression care.
1Days 1–3
100 mcg · once dailyAnecdotal systemic starting amount
2Days 4–7
100–200 mcg / dayOptional community-described step-up
3Weeks 2–4
Continue or stopShort course descriptions vary
4After course
Pause & reviewNo evidence-based break interval
What people commonly discuss100–200 mcg/day by subcutaneous injection for roughly 2–4 weeks appears in community protocol summaries.
What remains unvalidatedNo human study validates injected LL-37 at these amounts, a systemic escalation, antimicrobial efficacy or a repeat schedule.
ROUTE & DELIVERYTopical concentration cannot be converted to an injected dose
The wound trials used 0.5–3.2 mg/mL cream applied twice weekly within structured wound care. Concentration in a topical formulation does not equal systemic exposure.
PROFESSIONAL SOURCE CONTEXT
HEAL LL-37 phase IIb full paper ↗The source shows what has actually been studied. It does not validate the community example above or turn it into guidance.
Published human LL-37 protocols are topical wound-study protocols, not evidence for injected or general immune-support dosing.
PUBLISHED HUMAN RESEARCH
View source ↗First-in-man venous-leg-ulcer trial ↗
34 people with hard-to-heal venous leg ulcers
WHAT THIS TRIAL EXAMPLE SHOWS
This was a published human study. It involved 34 people with hard-to-heal venous leg ulcers. Route: Topical to ulcer. The study lasted 4 weeks after a 3-week run-in. The figures below describe the research design, not a personal schedule.
| First amount studied | 0.5 mg/mL cream arm |
|---|---|
| Later or target amount | 0.5, 1.6 and 3.2 mg/mL tested |
| How often? | twice a week |
| How was it given? | Topical to ulcer |
| How long? | 4 weeks after a 3-week run-in |
See the exact study wording +
Start / initial: 0.5 mg/mL cream arm
End / target: 0.5, 1.6 and 3.2 mg/mL tested
Frequency: Twice weekly
Route: Topical to ulcer
Study duration: 4 weeks after a 3-week run-in
Source: Grönberg et al., 2014 ↗
The two lower concentrations showed the strongest signal; the highest did not outperform placebo. This cannot be converted into an injection regimen.
PUBLISHED HUMAN RESEARCH
View source ↗HEAL LL-37 phase IIb trial ↗
148 people with hard-to-heal venous leg ulcers
WHAT THIS TRIAL EXAMPLE SHOWS
This was a published human study. It involved 148 people with hard-to-heal venous leg ulcers. Route: Topical to ulcer. The study lasted 13 weeks plus 4-month follow-up. The figures below describe the research design, not a personal schedule.
| First amount studied | 0.5 mg/mL cream arm |
|---|---|
| Later or target amount | 1.6 mg/mL second active arm |
| How often? | twice a week with compression |
| How was it given? | Topical to ulcer |
| How long? | 13 weeks plus 4-month follow-up |
See the exact study wording +
Start / initial: 0.5 mg/mL cream arm
End / target: 1.6 mg/mL second active arm
Frequency: Twice weekly with compression
Route: Topical to ulcer
Study duration: 13 weeks plus 4-month follow-up
Source: Mahlapuu et al., 2021 ↗
No significant benefit in the full cohort. The larger-ulcer result was post hoc and needs confirmation.
COMMUNITY DISCUSSION
Anecdotal / unvalidated · not equivalent to topical trialsWhat people commonly discuss
STARTING APPROACHES
Community injection descriptions often start around 100 mcg/day and may move toward 200 mcg/day. These amounts have no validating human dose-finding study.
DURATION / CYCLES
Short 2–4-week courses are commonly described; topical use is product- and wound-specific.
MAINTENANCE DISCUSSION
No validated systemic titration, maintenance or break schedule exists.
Community patterns are anecdotal and unvalidated unless a linked human study independently supports the same approach.
CALCULATOR TOOLS
Work with the numbers
Convert amounts, concentration, liquid volume and vial requirements. These tools do the arithmetic; they do not select a dose.
NEED HELP READING THE NUMBERS?Source labels, routes and dose termsOpen guide +
HOW WE LABEL NUMBERSKnow where a dose came from before you compare it.
Authorised labelHuman trialCommunity-describedBEFORE THE NUMBERS: CHECK THE PRODUCT
Understand peptide testing →A dose only means something if the vial contains what the label says.
Purity, identity, quantity, sterility and endotoxin testing answer different questions. Learn how to read a COA and why a high purity percentage is not the same as confirming the amount in the vial.
READ THIS PAGE IN THREE STEPS
Understand the study before the number
A dose only makes sense alongside the population, route, frequency and duration. Start with where the number came from, then look at how it was delivered and how long the study actually ran.
1Source
Was it an authorised label, a human trial or a community-described pattern?
2Route & frequency
How was it given, and how often? The same number by a different route may not mean the same exposure.
3Duration
Was this one dose, a short trial or long-term treatment? A study window is not automatically a recommended cycle.
ROUTES EXPLAINED
Plain-English guideWhat do the injection types mean?
Route means how a compound was delivered. It affects absorption and can completely change how a study should be interpreted.
SubQ / SCSubcutaneous
An injection into the fatty layer just under the skin.
Common in peptide and metabolic-drug studies. It usually aims for systemic absorption rather than treating only the spot injected.IMIntramuscular
An injection into muscle tissue.
Muscle can absorb a medicine differently from fat. An IM amount should not be assumed to be equivalent to a SubQ amount.IVIntravenous
Delivered directly into a vein.
This gives immediate bloodstream exposure and is commonly used in supervised research or clinical settings. It is not interchangeable with a home injection route.INIntranasal
Delivered through the nose rather than by injection.
The amount delivered depends on formulation and device. A spray count alone does not tell you the dose unless concentration and spray volume are known.Other routes you may see:Oral = swallowed.Topical = applied to skin or another surface.Implant = a formulation placed under the skin by a trained professional.
CALENDAR SETUP
Topical wound-study guide
Human trials · topical, condition-specificHuman studies used cream concentrations in mg/mL, applied with wound care. Concentration alone does not give the peptide mass per application. Record application reminders using the actual wound-care schedule; the studies do not establish an injectable regimen.
Form and route: Topical study cream applied to venous leg ulcers
The planner keeps amounts and repeat patterns blank for this compound. Use its formulation guide to record an independently specified schedule.
PLAIN-ENGLISH GLOSSARYWhat do the dose terms mean?Open glossary +
mgmilligram
One thousand micrograms (mcg).
mcg / μgmicrogram
One thousandth of a milligram.
mcg/kgweight-based dose
The amount is calculated for each kilogram of body weight.
IUinternational unit
A measure of biological activity used for some medicines; it cannot be converted to mg without compound-specific information.
Routehow it was given
For example SubQ, IM, IV, intranasal, oral or topical.
Frequencyhow often
For example once daily, twice weekly or every seven days.
Titrationplanned step-up or step-down
A protocol changes the amount over time rather than using one fixed amount throughout.
Half-lifehow quickly levels fall
The time taken for the amount of a compound in the body to reduce by roughly half. It can influence study timing but does not by itself define a schedule.
Cyclea defined period of use
Usually means an on-period followed by a stop or review. Many community 'cycles' have not been clinically validated.
Maintenancea continuing phase
A longer-term amount or interval used after an initial phase when a study or authorised treatment actually defines one.
Reconstitutionturning powder into solution
Adding a specified liquid to a freeze-dried vial so a concentration can be calculated.
U-100 unitssyringe volume markings
100 units equals 1 mL on a U-100 insulin syringe. The markings show volume, not peptide mass.
Often combined with
OFTEN COMBINED WITH
Community rationale · component roles · evidence boundaryWhy people explore pairings with LL-37
See the thinking behind community-named stacks, the different role each component is proposed to play, and how much of that idea has actually been tested as a combination.
Potential first, evidence in context. Pairings are usually explored because their research stories appear complementary. That makes them interesting to study, but does not yet prove extra benefit or safety.
CURRENT COMPOUNDLL-37
→
OFTEN EXPLORED WITHLL-37 + wound standard care
Topical LL-37 + Compression / wound care
→
OFTEN EXPLORED WITHLL-37 + thymosin alpha-1
LL-37 + Thymosin alpha-1
→
OFTEN EXPLORED WITHLL-37 + BPC-157
LL-37 + BPC-157
Combination-specific human research is the strongest evidence for what a pairing adds. Evidence for either ingredient alone should not be silently transferred to the combination.
LLL-37 IS USUALLY DISCUSSED AROUNDHost defence, wound biology and context-dependent inflammation
＋The strongest human setting is topical venous-ulcer care; systemic antimicrobial and immune-support use remains unvalidated.
PTHE PAIRED APPROACH MAY ADDStructured wound care or a second immune-modulating story
Compression and wound care belong to the tested clinical context. Thymosin alpha-1 is a community rationale, not a proven synergy.
＋
OFTEN EXPLORED WITH
Explore →＋LL-37 + wound standard care
Topical LL-37 + Compression / wound careWHY IT IS EXPLOREDHuman trials evaluated LL-37 as an adjunct within structured wound care.
Relevant only to the studied topical wound setting.OFTEN EXPLORED WITH
Explore →＋LL-37 + thymosin alpha-1
LL-37 + Thymosin alpha-1WHY IT IS EXPLOREDCommunity pairing combines host-defence and immune-modulation narratives.
No controlled combination trial establishes added benefit or safety.OFTEN EXPLORED WITH
Explore →LL-37 + BPC-157
LL-37 + BPC-157WHY IT IS EXPLOREDOften framed as combining antimicrobial or barrier defence with repair signalling.
There is no controlled human evidence for this pairing, route or combined safety.01Match the route
Topical wound evidence cannot be transferred to an injected immune stack.
02Avoid infection delay
Suspected infection needs diagnosis and appropriate antimicrobial care, not an experimental pairing.
03Watch immune complexity
Combining immune-active compounds can increase uncertainty rather than create balanced immunity.
Safety context
SAFETY & UNCERTAINTY
Concentration and route materially change the risk
01ENCOURAGING CONTEXTTopical human exposure has been studied
Two randomized venous-ulcer trials provide condition-specific tolerability data beyond laboratory research alone.
02THE IMPORTANT BOUNDARYHost defence is not simply immune boosting
LL-37 can be antimicrobial, repair-supporting, inflammatory or cytotoxic depending on concentration and tissue context.
03WHAT REMAINS UNKNOWNSystemic and chronic exposure
Injected pharmacokinetics, organ exposure, interaction risk and long-term immune effects are not established in people.
What the current evidence saysLL-37 can be cytotoxic or pro-inflammatory at some concentrations and is implicated in inflammatory skin biology. Small topical trials cannot establish the safety of systemic injection or chronic exposure.
01 · OBSERVEDPublished safety findings
The summary above reflects the human or preclinical evidence currently represented on this profile.
02 · UNCERTAINGaps still matter
Limited follow-up, small studies or absent controlled trials can leave uncommon and longer-term risks unresolved.
03 · CONTEXTProduct and regulatory status
Route, product identity, quality and regulatory status can materially change the safety context; see the linked status sources below.
Hard-to-heal ulcers and suspected infection can require vascular review, debridement, compression or antimicrobial treatment.
Milligrams per millilitre in a cream does not describe absorbed dose or validate a systemic amount.
Unapproved injectable products add contamination, concentration and sequence-verification uncertainty.
Sources & current status
READ FURTHER
Sources & current status
Follow the professional sources used across this profile, then see how the compound is currently described in regulatory and research terms.
KEY RESEARCH RECORD
7 sourcesSources used on this profile
Original publicationLL-37 in hard-to-heal venous leg ulcersJournal / DOI ↗Bibliographic recordLL-37 in hard-to-heal venous leg ulcersPubMed ↗Original publicationHEAL LL-37 phase IIb venous-leg-ulcer studyFree full paper ↗Original publicationHEAL LL-37 phase IIb venous-leg-ulcer studyJournal / DOI ↗Bibliographic recordHEAL LL-37 phase IIb venous-leg-ulcer studyPubMed ↗Professional sourceUnited KingdomMHRA products database ↗Professional sourceUnited StatesFDA Drugs@FDA database ↗
CURRENT STATUS
How to interpret its position today
No UK-authorised medicine is represented on this profile
LL-37 is presented as a research compound. The MHRA products database should be checked for any future change in authorised status.
MHRA products database ↗No FDA-approved therapeutic product identified
Regulatory evaluation of a substance for compounding is separate from approval of a drug for safety and efficacy.
FDA Drugs@FDA database ↗Profile reviewed against its linked source record on 20 September 2026. See how evidence is assessed.