Best peptides for immune support
Peptides that modulate immune function, support immune defense, and help regulate inflammatory responses.
What to know
Thymosin Alpha-1 is the gold standard immune peptide — FDA-approved in 35+ countries for hepatitis B/C and as an immune adjunct. LL-37 is a natural antimicrobial peptide with broad-spectrum activity. These peptides modulate rather than simply boost immunity, which is an important distinction for autoimmune considerations. Immune peptide protocols are typically used short-term (2-4 weeks) or cyclically.
Recommended peptides
LL-37
healing-recovery
LL-37 is a human antimicrobial peptide (cathelicidin) that plays a key role in innate immune defense against bacteria, viruses, and fungi.
BPC-157
healing-recovery
BPC-157 (Body Protection Compound-157) is a synthetic pentadecapeptide consisting of 15 amino acids derived from a protective protein found naturally in human gastric juice. First isolated and characterized by researcher Predrag Sikiric and his team at the University of Zagreb in the early 1990s, BPC-157 has become one of the most extensively studied peptides in preclinical research, with over 100 published studies investigating its effects across multiple organ systems. The compound earned the nickname "the Wolverine peptide" in biohacking communities due to the breadth of tissue repair observed in animal studies. Research spanning more than three decades has documented effects on tendons, ligaments, muscles, bones, skin, corneas, the gastrointestinal tract, liver, and nervous system in preclinical models. A 2025 systematic review published in HSS Journal (PMID: 40756949) analyzed 36 studies conducted between 1993 and 2024, finding that BPC-157 consistently improved outcomes across musculoskeletal injury models. Despite this extensive preclinical evidence, human clinical data remains extremely limited. As of March 2026, only three small human studies have been published: a 2-person intravenous safety pilot (PMID: 40131143), a small retrospective knee pain study, and a 12-patient interstitial cystitis pilot. The knee pain study reported significant relief in most participants at 6-12 months, and the cystitis pilot reported substantial symptom improvement. Neither of these smaller studies has been published with full peer-reviewed PMIDs. A Phase I safety trial (NCT02637284) was registered by PharmaCotherapia but the sponsor never published results, raising transparency concerns in the research community. BPC-157 is classified as a research compound and is not FDA-approved for any human use. In 2023, the FDA placed BPC-157 in Category 2 of its list of bulk drug substances under evaluation for compounding, meaning it does not meet safety criteria for pharmacy compounding. The World Anti-Doping Agency (WADA) added BPC-157 to its prohibited substances list in 2022 under the S0 category (non-approved substances). Despite these regulatory designations, BPC-157 continues to be widely discussed in peptide research communities and functional medicine circles. The compound is available in injectable and oral forms. Most preclinical research has used subcutaneous or intraperitoneal injection, though studies have also demonstrated activity when administered orally, particularly for gastrointestinal conditions. An important distinction exists between the acetate salt and arginate salt forms. The arginate form reportedly demonstrates significantly better oral bioavailability and stability, though head-to-head bioavailability studies have not been published in peer-reviewed journals. A comprehensive preclinical safety evaluation published in Regulatory Toxicology and Pharmacology (PMID: 32334036) tested BPC-157 across multiple species including mice, rats, rabbits, and dogs. The study found no test-related adverse effects in single-dose or repeated-dose toxicity evaluations, no genetic toxicity, and no embryo-fetal toxicity at doses up to 20 mg/kg over six weeks. However, the absence of large-scale human safety trials means that the long-term safety profile in humans remains unknown. The primary mechanisms through which BPC-157 appears to exert its effects involve the promotion of angiogenesis, modulation of nitric oxide synthesis through multiple pathways, upregulation of growth factor receptors, and interaction with the dopamine and serotonin neurotransmitter systems. These mechanisms have been documented across dozens of studies spanning multiple research groups. BPC-157 occupies a unique position in the peptide landscape. Its broad preclinical evidence base across tissue types, combined with the near-total absence of human clinical trials, creates a significant gap between what animal research suggests and what has been demonstrated in people. All information on this page reflects published research and is presented for educational purposes only.
Selank
nootropic
Selank is a synthetic analog of the immunomodulatory peptide tuftsin with anxiolytic and nootropic properties, approved for clinical use in Russia.
Thymosin Beta-4
healing-recovery
Thymosin Beta-4 is the full-length naturally occurring protein from which TB-500 is derived. It plays a central role in tissue repair, cell migration, and immune modulation.
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Written by Alejandro Reyes
Founder & Lead Researcher
Reviewed by Peptide Nerds Editorial · Updated April 2026