Other · 5mg × 10 vials
LL-37 is what your own immune system uses to crack open biofilms and punch holes in bacteria, given as a research peptide for people whose endogenous production isn't keeping up with a chronic infection load.
LL-37 is the active 37-amino-acid fragment of human cathelicidin (hCAP-18, gene CAMP), the body's own broad-spectrum antimicrobial peptide. It is part of the innate immune system's first line of defense and is produced by neutrophils, epithelial cells in the skin/lung/gut, and macrophages. Mechanism is multi-pronged: (1) direct microbe killing by inserting an amphipathic alpha-helix into bacterial, fungal, and enveloped-viral membranes, causing membrane disruption and lysis; (2) biofilm dispersal at sub-inhibitory concentrations, which is the single most-cited reason it's used in chronic infection protocols (biofilms are the bacterial "fortress" that lets Borrelia, Staph, Pseudomonas, and Candida persist through antibiotics); (3) immunomodulation, where LL-37 chemoattracts neutrophils/monocytes/T cells, modulates TLR signaling, and tunes cytokine output up or down depending on context; (4) wound healing and angiogenesis through formyl peptide receptor-like 1 (FPRL1/FPR2) activation. Endogenous LL-37 expression is vitamin-D-dependent: 1,25(OH)2D binding to VDR drives CAMP gene transcription, which is the mechanistic link behind the long-observed "low vitamin D, more infections" pattern. Exogenous administration short-circuits the vitamin D step and delivers the active peptide directly. In plain language: LL-37 is what your own immune system uses to crack open biofilms and punch holes in bacteria, given as a research peptide for people whose endogenous production isn't keeping up with a chronic infection load.
Typical dose ranges by experience level - educational reference. Message us and we tailor it to you.
Beginners with chronic Lyme/long-COVID/biofilm history should expect a Herxheimer-style reaction in week 1-2 (fatigue worsens, brain fog spikes, sometimes a transient skin flare). This is endotoxin release from disrupted biofilms, not a drug allergy. Reduce dose to 50 mcg/day or pause 3-5 days if reaction is severe. Pair with binders (activated charcoal, chlorella) 2 hr away from peptide injection if Herx is heavy. Vitamin D level should be checked first - running LL-37 on top of frank vitamin D deficiency wastes the protocol because endogenous expression won't co-amplify.
200 mcg/day is the working dose for active chronic infection (Lyme, post-acute COVID with persistent symptoms, recurrent Staph/MARCoNS, chronic Candida overgrowth). At this band most protocols add Thymosin Alpha-1 (Tα1) at 1.6 mg twice weekly for immune amplification and BPC-157 250-500 mcg/day for gut lining repair during clearance. Off-week protocols vary: hard stop for 2-4 weeks, or step back to 100 mcg/day maintenance for chronic cases.
300 mcg/day is the practical ceiling in community use; some functional medicine protocols (Carl Lanore's published version) used 125 mcg/day for 50 days straight rather than escalating, which is an alternate route to similar total exposure. Above 300 mcg/day is where the autoimmune skin flare risk climbs sharply (rosacea/psoriasis exacerbation is dose-dependent in animal models). Advanced cycling is almost always paired with the full chronic-infection stack: LL-37 + Tα1 + BPC-157 + NAD+, with cycling staggered so LL-37 off-weeks become Tα1-driven immune maintenance weeks.
Straight talk - what people actually report, and what the studies measured.
Peer-reviewed studies and clinical guidelines - tap any to read the source.
](https://pmc.ncbi.nlm.nih.gov/articles/PMC3346901/) - foundational review on LL-37 structure, function, and skin disease implications
Read study ↗PubMedThe vitamin D-antimicrobial peptide pathway and its role in protection against infection (Hewison 2009, PMID 19895218)](https://pubmed.ncbi.nlm.nih.gov/19895218/) - vitamin D / VDR / CAMP gene expression mechanism
Read study ↗PubMedVitamin D-Cathelicidin Axis: at the Crossroads between Protective Immunity and Pathological Inflammation during Infection (PMID 32395364)](https://pubmed.ncbi.nlm.nih.gov/32395364/) - the dual nature of LL-37 across protective vs pathological inflammation
Read study ↗PubMedThe Potential of Human Peptide LL-37 as an Antimicrobial and Anti-Biofilm Agent (PMC8227053)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8227053/) - biofilm disruption mechanism and clinical relevance
Read study ↗PubMedAntimicrobial peptide LL-37 is bactericidal against Staphylococcus aureus biofilms (PMC6553709)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6553709/) - direct evidence on Staph biofilm eradication, >4 log reduction
Read study ↗PubMedUpregulating Human Cathelicidin LL-37 Expression May Prevent Severe COVID-19 (PMC9134243)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9134243/) - COVID-19 inflammatory response and microthrombosis rationale
Read study ↗Aggregated sentiment from public forums & socials - real-world reports, not individual endorsements.
Herxheimer reactions (worsening fatigue, brain fog, joint pain, sometimes brief fever) in first 1-2 weeks: extremely common in chronic Lyme/biofilm users, severity proportional to pathogen load. Most users describe it as confirmation the peptide is working, not a side effect to fear, but it can be debilitating in heavy cases.
- Divergence: Literature flags injection site reactions and immune activation as primary AEs; community emphasizes Herx as the dominant first-cycle experience, and the literature mostly under-discusses it because clinical trials excluded heavy chronic infection patients.
Injection site redness/welt that lingers 24-48 hours: more common than with BPC/TB; manageable with site rotation
Facial flushing / rosacea flare at sustained 200+ mcg/day: small but real signal in community reports, more common in users with pre-existing rosacea history
Skin sensitivity / mild psoriasis-like patches in users with prior psoriasis: a known dose-dependent risk, community usually titrates back or cycles off
Fatigue persisting past Herx window: occasional, usually means dose is too aggressive for current pathogen load, drop to 50-100 mcg/day for a reset
Route: SubQ
Injection site: abdomen or outer thigh, rotate sites; some protocols inject near a localized infection site (e.g. lower-abdomen near affected lymph regions) but standard SubQ is fine for systemic effect
Storage: refrigerated 2-8°C, use within 14-21 days (shorter than most peptides; LL-37 is freshness-sensitive). Unreconstituted vials freezer for long-term, fridge if using soon. Shield from light.
Notes: Swirl gently to mix, never shake (peptide is structurally fragile). Allow to reach room temp before injecting once mixed. Use a fresh insulin syringe per draw. Some protocols split the daily dose AM/PM to keep tissue levels steady given the short plasma half-life. Pre-medicate with antihistamine if injection-site reactions become bothersome (more common with LL-37 than with BPC/TB-500).