LL-37 Dosage Guide, Benefits & Side Effects

LL-37 Dosage Guide, Benefits & Side Effects

LL-37 disrupts pathogen membranes, speeds wound healing in ulcers, and modulates immune response, with early antitumor trial data too.

Chemical Makeup

27

Amino Acids

LL-37

Ala

Position 1

Pro

Position 2

Val

Position 3

Ser

Position 4

Position 5

Gly

Position 6

Position 7

Position 8

Thr

Position 9

Position 10

Leu

Position 11

Position 12

Lys

Position 13

Met

Position 14

Tyr

Position 15

Position 16

Arg

Position 17

Position 18

Asn

Position 19

His

Position 20

Trp

Position 21

Position 22

Position 23

Position 24

Position 25

Position 26

Position 27

As seen on

LL-37 Dosage Guide for Immune & GutLL-37 Dosage Calculator

LL-37 has antimicrobial properties and supports healing, given as an injection under the skin.

Vial size

5 mg

Bacteriostatic water

2 mL

Dosing

100 mcg

Frequency

Daily

Cycle

4–6 weeks

Benefit

Immune & Gut

What is LL-37?

LL-37 is a naturally occurring peptide made by your immune system, including white blood cells and skin cells, that acts as a first line of defense against infection. It works by physically breaking apart the outer membranes of harmful microbes while also helping coordinate the immune system's broader response. It's studied for wound healing, fighting stubborn infections, and even some cancer research.

Healing

Research targets include tissue repair, wound healing, and recovery from injury.

Immunity

Research targets include immune cell activity, inflammatory response, and infection defense.

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Is LL-37 FDA approved?

LL-37 is not an FDA-approved drug. It is intended for research purposes only and is not approved for human consumption, diagnostic, or therapeutic use.

Research Use Only

LL-37 has not been evaluated by the FDA for safety or efficacy in humans.

No Clinical Oversight

Not manufactured under FDA-regulated quality or clinical standards.

Unregulated Sourcing

Purity, dosing, and sourcing are not verified through FDA testing or oversight.

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How Does LL-37 Work?

Because it carries a strong positive charge, it's drawn to and punches into the outer coating of bacteria, breaking them open. Beyond directly killing microbes, it also acts on the body's own cells to help coordinate the wider immune response, encourage new blood vessel growth, and call in immune cells to the area.

Drawn to bacteria

Its positive charge is drawn to the outer coating of bacteria.

Breaks them open

Punches into that coating, breaking the bacteria apart.

Coordinates the immune system

Also helps call in immune cells and encourage new blood vessel growth.

LL-37 Targeted areas

How to reconstitute LL-37

The materials you'll need and step-by-step instructions for safely mixing LL-37 with bacteriostatic water.

Materials needed

Your LL-37 vial (lyophilized)

Alcohol swabs

Bacteriostatic sterile water

3 mL syringes (Luer Lock tip)

25G or 27G needles (Luer Lock). Other gauges may also be acceptable.

Sharps container (optional)

Remove the caps

Sanitize the rubber stoppers

Attach the needle

Draw the bac water

Pull back on the plunger to draw your desired volume of bacteriostatic water. If you overfill, just push the excess back in until you reach the right marker on the syringe.

Insert the needle into the LL-37 vial

With the bac water in your syringe, insert the needle into the LL-37 vial at a slight angle to avoid pressure buildup.

Release the water gently

Let the water run gently down the side of the vial. Don't inject it forcefully.

Swirl to dissolve

Avoid shaking. Gently swirl, flip, and roll the vial to dissolve the powder.

Check for full dissolution

Cap, dispose, and store

How to Store LL-37

The dry powder can handle room temperature for a few weeks, but freezing it well below zero is best for long-term storage. Once mixed with liquid, refrigerate for a few days or freeze it, avoiding repeated freezing and thawing.

Lyophilized Storage

Stable at room temperature up to 3 weeks; store desiccated below -18°C for long-term.

Reconstituted Storage

Refrigerate at 2–8°C for 2–7 days, or store below -18°C.

Handling Notes

Avoid freeze-thaw cycles.

What Are the Benefits of LL-37?

What research says it may help with, and how it works in the body.

wound healing

In clinical trials, a 0.5mg/mL dose shrank ulcer size by 68%.

Helps new tissue form at wound sites and speeds up wound closure.

Sped up healing in animal studies.

immunity

Strengthens the body's natural defenses against germs.

Fights MRSA and other drug-resistant bacteria, cutting bacterial colonies (biofilms) by more than 10,000-fold in lab tests.

Helps regulate the immune system without weakening it overall.

skin health

Encourages skin cells to grow and renew themselves.

Encourages the growth of new blood vessels to support tissue repair.

Helps the body produce collagen to support wound healing.

What Are the Side Effects of LL-37?

Who should avoid it, warning signs to watch for, and what to know before combining it with other compounds.

Who Should Avoid It

Pre-existing hypersensitivity to peptides

Compromised immune status (relative contraindication)

Non-sterile wound environments

Stop Right Away If You Notice

Severe injection site reactions with spreading inflammation

Allergic reaction signs (rash, difficulty breathing, swelling)

Persistent flu-like symptoms

Signs of wound infection (increased redness, warmth, drainage)

Worsening wound condition or delayed healing

Unusual pain or irritation at application site

Milder Signs to Watch For

How Long Should a LL-37 Cycle Last?

This breaks down how long a typical LL-37 cycle runs and what research suggests happens at each stage. Research shows that staying on a peptide continuously, without a break, may make it less effective over time.

That's why most research protocols build in a break between cycles, often called a washout period, to let the body reset before starting again.

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Cheat Sheets Featuring LL-37

See how LL-37 fits into a broader research stack with these free downloadable cheat sheets. Each one includes reference dose ranges, dosing frequency, and half-life for every peptide it covers. For research purposes only.

18 peptides

15 peptides

78 peptides

Browse user-created protocols

Real protocols from the community that include LL-37

Dr. JRSW

Jana

nad

Weight

GLP-3

LL-37 Research References

It is a phase 2 compound

LL-37 is a phase 2 compound

68% ulcer area reduction demonstrated at optimal doses in chronic venous leg ulcers.

n.d.

Intratumoral LL-37 in melanoma patients demonstrated safety and immune stimulation (NCT02225366).

2015

>4 log reduction in MRSA biofilms compared to conventional antibiotics.

NMR spectroscopy determining 3D structure of LL-37.

Frequently Asked Questions About LL-37

Straight answers on reconstitution, dosing, and safety, everything you need to research with confidence. For research reference only.

What is LL-37 and how does it work?

LL-37 is the only cathelicidin-family antimicrobial peptide produced naturally in the human body (derived from the precursor protein hCAP18). It is a cationic peptide that binds electrostatically to negatively charged microbial membranes, disrupting them and causing cell death in bacteria, fungi, and some viruses. Beyond direct antimicrobial action, it neutralizes bacterial toxins like LPS, helps break down biofilms, and modulates the immune system by recruiting immune cells and influencing inflammation, which is why it is studied for both infection control and wound healing.

What dosages are commonly used or discussed for LL-37?

There is no clinically validated injectable dosing protocol for LL-37 in humans. The strongest human evidence comes from topical wound-care trials using gel concentrations of 0.5 mg/mL and 1.6 mg/mL applied to venous leg ulcers, not from injections. In research and biohacking communities, subcutaneous protocols circulating online typically describe 100-200 mcg per day (sometimes split into two 50-100 mcg doses), used 5 days a week for 2-6 weeks followed by a break, but these regimens are anecdotal and have not been validated in peer-reviewed human trials. Animal studies used doses (up to 1-5 mg/kg) that do not translate directly to human dosing.

How should LL-37 be reconstituted and stored?

LL-37 is typically supplied as a lyophilized (freeze-dried) powder. Lyophilized peptide is generally stable for months when kept sealed, desiccated, and stored at or below -18 to -20°C (room temperature storage for short periods is sometimes tolerated but shortens shelf life). It is commonly reconstituted with bacteriostatic or sterile water by slowly injecting the liquid down the inside wall of the vial to avoid foaming/denaturation, then left to dissolve without shaking. Once reconstituted, it is generally recommended to store the solution refrigerated (about 2-8°C) and use it within roughly 28-30 days, avoiding light exposure, heat, and repeated freeze-thaw cycles.

What side effects or risks are associated with LL-37?

In controlled topical wound-healing trials, LL-37 has shown a generally favorable safety profile with few adverse events attributed to treatment. However, laboratory studies show LL-37 can be cytotoxic to human cells at higher concentrations (roughly 1-10 micromolar range), and it is notably elevated in inflammatory skin conditions such as psoriasis and rosacea, raising questions about its role in inflammatory disease. There is essentially no controlled human safety data for injectable or systemic use, so risks of that route (site reactions, immune effects, unknown long-term effects) are not well characterized. Anyone considering use should be aware these products are not evaluated by regulators for human administration.

Is LL-37 legal to buy, and is it approved for human use?

LL-37 is not FDA-approved (or approved by comparable regulators elsewhere) for human or veterinary use. It is widely sold by peptide vendors explicitly labeled 'for research use only, not for human consumption,' intended for laboratory and in-vitro research by qualified professionals. Regulatory status can vary by country, but purchasing it for personal use falls outside its labeled and approved purpose, and quality/purity can vary significantly between suppliers.

What is the evidence for LL-37 and wound healing?

The clearest human clinical evidence for LL-37 comes from trials of a topical gel applied to chronic venous leg ulcers, where the treated groups (0.5 mg/mL and 1.6 mg/mL) showed meaningfully higher rates of complete wound healing compared to placebo. This is distinct from the injectable protocols discussed in online communities, which lack equivalent clinical trial support. The topical/gel route remains the best-documented application of LL-37 in humans to date.

Can LL-37 be stacked with other peptides?

Some online sources and users describe combining LL-37 with peptides like BPC-157 or TB-500, reasoning that these may support tissue repair or modulate immune response alongside LL-37's antimicrobial and wound-healing effects. These combinations are based on anecdotal reports and theoretical mechanisms rather than controlled studies, and there is no clinical research establishing safety or added benefit from stacking LL-37 with other peptides.

Does LL-37 have a role in immunity beyond fighting infection?

Yes. Research indicates LL-37 has both pro-inflammatory and anti-inflammatory functions depending on context: it can recruit and activate immune cells, promote wound-related angiogenesis (new blood vessel formation), and help regulate excessive inflammatory responses. At the same time, abnormally high LL-37 levels are associated with autoimmune and inflammatory skin conditions, suggesting its immune signaling effects are concentration- and context-dependent rather than uniformly beneficial.