Thymosin Alpha-1

PEPTIDES+ MEMBERS ONLY

INDICATIONS FOR USE

Thymosin Alpha-1 (Tα1) is used for its immunomodulatory properties. It is indicated for treating chronic viral infections such as hepatitis B and C, immune dysfunction in cancer, and as adjunct therapy to enhance vaccine responses. Off-label, it is used for autoimmune diseases, chronic fatigue syndrome, and other conditions with impaired immunity.

ROUTE OF ADMINISTRATION

  • Administered subcutaneously.

COMMON INITIAL DOSING REGIMENS

  • Standard dosing is 1.6 mg to 3.2 mg administered subcutaneously two to three times per week. In chronic conditions, extended courses of 6–12 months or longer may be necessary, depending on response.

MECHANISM OF ACTION

  • Thymosin Alpha-1 is a naturally occurring peptide derived from the thymus gland. It works by restoring immune balance through T-cell activation and regulation. Tα1 enhances cytotoxic T-cell and natural killer (NK) cell activity, increases cytokine production, and improves antigen presentation by dendritic cells.

  • It promotes immune surveillance and pathogen elimination by shifting the immune system toward a Th1-dominant response, favoring pro-inflammatory cytokine production (e.g., IFN-γ, IL-2). This makes it particularly effective in combating viral infections and certain cancers. Additionally, it suppresses excessive inflammation by modulating regulatory T-cell (Treg) activity, reducing tissue damage during infections or autoimmune conditions.

COMMON SIDE EFFECTS

  • Localized Reactions: Redness, pain, or swelling at the injection site, typically mild.

  • Systemic Effects: Fatigue, headache, dizziness, or mild flu-like symptoms may occur but are generally transient.

  • Rare Reactions: Hypersensitivity reactions, such as rash or anaphylaxis, are extremely rare but possible.

  • Immunological Concerns: Overactivation of the immune system may exacerbate autoimmune conditions in predisposed individuals.

CONTRAINDICATIONS

  • Absolute: Hypersensitivity to Thymosin Alpha-1 or any excipient.

  • Relative: Use cautiously in patients with severe autoimmune disorders, as immune modulation may worsen disease activity. Limited safety data advises avoiding use in pregnant or breastfeeding individuals.

COMPARISON WITH LL-37

  • Thymosin Alpha-1 and LL-37 both modulate immune responses but differ in focus. Tα1 primarily enhances adaptive immunity, stimulating T-cell activity and supporting the clearance of viral infections and cancer. It is ideal for chronic viral illnesses, cancer immunotherapy, and conditions with suppressed immunity.

  • LL-37, in contrast, is focused on antimicrobial activity and innate immunity. It directly combats bacterial infections by disrupting biofilms and killing pathogens, making it better suited for resistant infections and wound healing.

  • While Tα1 offers a systemic boost to immune function, LL-37 addresses localized infections and inflammation. Their complementary mechanisms may allow combination use for infections with immune suppression or biofilm-related complications.

MORE INFORMATION

  • FDA Safety Data Sheet not available (experimental peptide therapy).

  • Dinetz E. Comprehensive Review of the Safety and Efficacy of Thymosin Alpha 1 in Human Clinical Trials. Altern Ther Health Med. 2024 [PubMed Link]

  • Dominari A. Thymosin alpha 1: A comprehensive review of the literature. World J Virol. 2020 [PubMed Link]

  • Cao A. Thymosin Alpha 1 Plus Routine Treatment for the Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis. J Coll Physicians Surg Pak. 2024 [PubMed Link]

  • Wei Y. Thymosin α-1 in cancer therapy: Immunoregulation and potential applications. Int Immunopharmacol. 2023 [PubMed Link]

  • Soeroto AY. The efficacy of thymosin alpha-1 therapy in moderate to critical COVID-19 patients: a systematic review, meta-analysis, and meta-regression. Inflammopharmacology. 2023 [PubMed Link]

  • Garaci E. Phenotypic drug discovery: a case for thymosin alpha-1. Front Med (Lausanne). 2024 [PubMed Link]

  • Tian Y. Thymosin alpha 1 alleviates inflammation and prevents infection in patients with severe acute pancreatitis through immune regulation: a systematic review and meta-analysis. Front Immunol. 2025 [PubMed Link]

  • Mao L. Thymosin alpha 1 - Reimagine its broader applications in the immuno-oncology era. Int Immunopharmacol. 2023 [PubMed Link]

  • Minutolo A. Thymosin alpha 1 restores the immune homeostasis in lymphocytes during Post-Acute sequelae of SARS-CoV-2 infection. Int Immunopharmacol. 2023 [PubMed Link]

  • Bellet MM. Thymosin alpha 1 exerts beneficial extrapulmonary effects in cystic fibrosis. Eur J Med Chem. 2021 [PubMed Link]

  • Peng D. The clinical efficacy and adverse effects of Entecavir plus Thymosin alpha-1 combination therapy versus Entecavir Monotherapy in HBV-related cirrhosis: a systematic review and meta-analysis. BMC Gastroenterol. 2020 [PubMed Link]

  • Liu Y. Thymosin Alpha 1 Reduces the Mortality of Severe Coronavirus Disease 2019 by Restoration of Lymphocytopenia and Reversion of Exhausted T Cells. Clin Infect Dis. 2020 [PubMed Link]

  • Solmonese L. The Immunomodulatory Activity of Thymosin Alpha 1 on Tumor Cell Lines and Distinct Immune Cell Subsets. Onco Targets Ther. 2025 [PubMed Link]