LL-37: Better Than Antibiotics?

Happy Friday!

FYI - I just dropped a new video on J-147, Dihexa, and Noopept if you want to check it out:

For today’s email, I want to talk to you about a LL-37—a compound that’s capturing attention in biohacking and regenerative medicine circles, yet remains relatively unknown to the broader health-conscious audience.

As you probably know by now, I’m always hunting for cutting-edge therapies that enhance health, vitality, and longevity, and LL-37 certainly fits that bill.

I’ve personally used LL-37 to help heal viral infections on myself, and I have used it to improve my gut health dramatically.

In this deep dive, I’ll walk you through exactly what LL-37 is, where it comes from, how it works, and why it might be something you should pay attention to—especially if you’re looking to accelerate healing, boost immune function, or tackle challenging infections.

Let’s dive in!

What Exactly Is LL-37, and Where Does It Come From?

LL-37 is an antimicrobial peptide naturally produced by the human body as part of your innate immune system—the frontline defense against pathogens.

It comes from a gene called CAMP, and it’s initially produced as a larger molecule called hCAP-18, which is then cleaved into its active form, the 37-amino acid peptide we call LL-37.

You can find it produced naturally in your skin, respiratory tract, gut lining, and inside immune cells like neutrophils, macrophages, and even T-cells.

Interestingly, vitamin D3 levels heavily influence how much LL-37 your body produces, connecting sunlight exposure and immune function.

While LL-37 is naturally occurring, therapeutic forms are typically synthesized in laboratories using advanced peptide synthesis or recombinant technology, which enables us to employ it for therapeutic use.

How LL-37 Works: Healing, Defense, and Beyond

It has three powerful mechanisms:

1. Potent Antimicrobial Activity

LL-37 directly kills bacteria, fungi, and some viruses by disrupting their cell membranes.

This is particularly valuable against antibiotic-resistant infections or biofilm-forming bacteria, like those in chronic wounds or persistent infections.

2. Immunomodulation

Beyond killing microbes, LL-37 modulates your immune response.

It attracts immune cells to infection sites, reduces harmful inflammation by neutralizing bacterial endotoxins, and supports your immune system to efficiently resolve infections.

3. Tissue Healing and Regeneration

Perhaps most excitingly, LL-37 enhances healing and tissue regeneration.

It stimulates keratinocytes and fibroblasts, encouraging wound closure and collagen formation.

It even boosts angiogenesis—the growth of new blood vessels, critical for delivering nutrients and oxygen to healing tissues.

In chronic, difficult-to-heal wounds (like diabetic ulcers), LL-37 has shown remarkable promise in accelerating healing and restoring skin integrity.

Real-Life Benefits: Who Can LL-37 Help?

Given these mechanisms, LL-37 has broad potential. But let’s focus on practical applications:

• Chronic Wound Healing: Individuals with diabetic foot ulcers, venous leg ulcers, or pressure ulcers can significantly benefit from topical LL-37 treatments. Clinical trials have demonstrated faster healing times, reduced infection rates, and improved tissue regeneration.

• Infections Resistant to Antibiotics: If you’re struggling with recurrent infections or biofilm-driven conditions (like chronic sinusitis or persistent middle ear infections), LL-37 provides a powerful adjunct to traditional antibiotics, often clearing infections resistant to conventional treatment.

• Inflammatory and Autoimmune Conditions (With Caution): While LL-37 helps balance the immune response, it must be approached carefully in inflammatory or autoimmune contexts. Conditions like rheumatoid arthritis or psoriasis might actually worsen with excessive LL-37 use, because it can amplify certain autoimmune signals. However, careful, targeted use (often with professional oversight) might help resolve chronic inflammation by addressing underlying infections or healing damaged tissue. In this case, the right dosing is critical.

Side Effects and Risks: What You MUST Know

LL-37 is generally safe when administered correctly, but caution is essential:

• Cytotoxicity at High Doses: Excessive LL-37 can damage healthy cells, potentially leading to irritation, inflammation, or tissue damage. Clinical studies have found that lower, carefully regulated doses are most effective and safest.

• Autoimmune or Inflammatory Flare-ups: If you have an autoimmune condition (like lupus or severe psoriasis), LL-37 might exacerbate inflammation rather than alleviate it. This makes LL-37 unsuitable for people who already exhibit high LL-37 levels, as it may worsen their symptoms.

• Cancer Risks (Theoretical): LL-37 can potentially stimulate angiogenesis, which might theoretically feed tumors. While research is mixed—LL-37 also exhibits anti-tumor properties—it’s prudent to avoid LL-37 if you have active cancer or a history of cancer until more is understood. In my opinion, this is similar to how BPC-157 is often misinterpreted as “causing cancer” - it doesn’t, but we lack extensive data on its real-world use.

• Local Irritation: Topical application might occasionally lead to mild irritation or discomfort. Usually, this subsides quickly, but sensitive individuals should proceed cautiously.

Dosage and Administration: How to Use LL-37

While there’s no universal dosage yet (since it’s not yet FDA-approved), here’s my recommendation based on personal experience:

• Topical use for wounds: Effective concentrations range from 0.5–1.6 mg/mL, applied to the wound 1–2 times per week. Lower doses (around 0.5 mg/mL) appear most effective in trials, reducing the risk of irritation while optimizing healing effects.

• Duration: LL-37 is typically applied topically for several weeks—most studies show significant benefits after just 4 weeks of regular topical use. If improvement continues, longer treatment can be considered under supervision.

• Subcutaneous injection: This is the method I have personally used. To help with infections, including gut issues like SIBO, toe fungus, or any other bacterial, viral, or microbial infection, I recommend the following approach (and yes, I know this is slightly different from the cheat sheet, but you can use either protocol). 

Here’s how I would mix a 5mg bottle from BioLongevity Labs to get a 125mcg dose:

• Add 2ml of BAC water

• Withdraw 5 units (125mcg) into an insulin syringe

• Inject in a fasted state in the AM or PM once per day subcutaneously into the belly

NOTE: It does sting to inject, so just be ready!

Who Should (And Shouldn’t) Consider LL-37?

Good Candidates:

• Individuals with chronic, non-healing wounds (venous, diabetic ulcers)

• People dealing with persistent, antibiotic-resistant infections

• Those with compromised immune systems needing additional antimicrobial defense

Not Ideal Candidates:

• People with extreme cases of autoimmune conditions since they already have high levels of LL-37 the body is attempting to producte (psoriasis, lupus)

• Cancer patients (due to theoretical concerns of stimulating tumor growth)

• Those prone to severe inflammatory reactions or allergic responses

LL-37 Isn’t Magic

It’s important to emphasize: LL-37 isn’t a miracle cure-all.

It’s an exceptionally promising support for healing and immune function—but it works best alongside healthy lifestyle practices.

Nutrition, stress management, sleep, and regular exercise remain foundational.

LL-37 enhances your body’s natural healing power, but cannot substitute for a consistently healthy lifestyle.

It’s an advanced tool, perfect for certain situations, but not something to depend on alone to fix deeper, underlying health issues.

Final Thoughts

If you fit the criteria above and have been struggling with stubborn wounds, difficult infections, or weakened immunity, LL-37 could be a genuine game-changer for your healing journey.

It’s one of the most intriguing peptides available, with robust clinical backing in specific contexts.

Best,

Hunter

P.S. You can save 25% on LL-37 and and 19 other healing peptides this weekend at BioLongevity Labs as part of the Healing Sale. The products are discounted 10% already in the store, and when you use code HUNTERW, you will get an additional 15% off.