Reviewed by the PeptideMind Team · Updated August 5, 2026

LL-37 Peptide Dosage Guide, Benefits & Side Effects

LL-37 peptide (cathelicidin) dosage guide: injection protocols, wound healing, immune support, antimicrobial benefits, and side effects to know before use.

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LL-37 Dosage Schedule

A daily shot of an antimicrobial peptide studied for supporting the immune system and gut lining while it helps with general healing.

LL-37 Immune & Gut Support Protocol

5 weeks, focused on immune function.

Daily dosing

Taken daily.

100 mcg per injection

100 mcg per injection, given just under the skin in the abdomen or thigh.

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

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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.

Immunity

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What Does LL-37 Do?

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.

Frequently Asked Questions About LL-37

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

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.

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.

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.

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.

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.

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.

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.

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.

LL-37 Reconstitution Guide

LL-37 is supplied as a freeze-dried powder that must be mixed into a injectable solution before use. Available in 5mg, 10mg sizes.

5 mg lyophilized vial

LL-37 is supplied as a freeze-dried powder that must be mixed into a injectable solution before use. Available in 5mg, 10mg sizes.

2 mL bacteriostatic water

Adding 2 mL of bac water to a 5 mg vial gives a workable concentration for syringe dosing. More water makes microdosing easier; less concentrates each draw.

Storage after mixing

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. After reconstitution, keep the vial refrigerated and use within 30 days.

Reconstitution steps

Remove caps & sanitize stoppers

Attach needle to syringe

Draw 2 mL bacteriostatic water

Insert needle into LL-37 vial

Release water gently down the side

Swirl to dissolve — don't shake

Check for full dissolution

Refrigerate LL-37 — good for 30 days

Chemical Makeup

Amino Acids

LL-37

Ala

Position 1

Pro

Position 2

Val

Position 3

Ser

Position 4

Val

Position 5

Gly

Position 6

Gly

Position 7

Gly

Position 8

Thr

Position 9

Val

Position 10

Leu

Position 11

Ala

Position 12

Lys

Position 13

Met

Position 14

Tyr

Position 15

Pro

Position 16

Arg

Position 17

Gly

Position 18

Asn

Position 19

His

Position 20

Trp

Position 21

Ala

Position 22

Val

Position 23

Gly

Position 24

His

Position 25

Leu

Position 26

Met

Position 27

Amino acid sequence

AlaninePosition 1

ProlinePosition 2

ValinePosition 3

SerinePosition 4

ValinePosition 5

GlycinePosition 6

GlycinePosition 7

GlycinePosition 8

ThreoninePosition 9

ValinePosition 10

LeucinePosition 11

AlaninePosition 12

LysinePosition 13

MethioninePosition 14

TyrosinePosition 15

ProlinePosition 16

ArgininePosition 17

GlycinePosition 18

AsparaginePosition 19

HistidinePosition 20

TryptophanPosition 21

AlaninePosition 22

ValinePosition 23

GlycinePosition 24

HistidinePosition 25

LeucinePosition 26

MethioninePosition 27

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

Discolored or cloudy solutionsYellow discoloration or visible particlesPre-mixed liquid formulations (LL-37 unstable long-term)Non-sterile preparationsMicrobial contamination

Was it helpful?Yes

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.

A smartphone screen displaying FDA status for a drug, indicating "FDA approved drug: No" and "Classification: Research use only." A banner notes "Research Only" with the disclaimer "not for human use," emphasizing its intended use for laboratory and analytical purposes.

LL-37 Cycle Length: How Long Should It 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.

Week 1-2: Reduced bacterial load, initial wound bed preparation
Week 2-4: Increased granulation tissue formation, epithelial migration
Week 4-6: Significant wound size reduction
Week 6-8: Continued healing toward wound closure

LL-37 Research References

It is a phase 2 compound

4Research references

LL-37

LL-37 is a phase 2 compound

Venous Leg Ulcer Trial - Grönberg et al.

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

n.d.

Melanoma Phase I Trial

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

2015

MRSA Biofilm Study - Noore et al.

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

n.d.

Structural Analysis - Wang et al.

NMR spectroscopy determining 3D structure of LL-37.

n.d.

Browse user-created protocols

Real protocols from the community that include LL-37

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Dr. JRSW

250days

6 peptides·Healing·1mo ago

Jana

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Weight

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LL-37 Peptide Dosage Guide, Benefits & Side Effects

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