Thymosin Alpha-1 (Zadaxin) Pricing: April 2026

Thymosin Alpha-1 (Tα1, thymalfasin) is a 28-amino-acid peptide that modulates the immune system. It was first isolated from thymus tissue, and its main use is immune support.

Zadaxin: SciClone Pharmaceuticals makes the branded version, Zadaxin. It is FDA-approved or the equivalent in 35+ countries for chronic hepatitis B, chronic hepatitis C, and as a cancer adjuvant (a drug given alongside cancer treatment). It is not FDA-approved in the US. FDA has granted it orphan drug status for malignant melanoma, chronic active hepatitis B, DiGeorge anomaly, and hepatocellular carcinoma. Orphan status is an incentive for rare-disease drugs and does not mean approval.

Regulatory status (April 2026): FDA put Thymosin Alpha-1 on its Category 2 list in late 2023, which restricted compounding. On February 27, 2026, HHS Secretary RFK Jr. said Tα1 was one of 14 peptides moving back to Category 1. That restores legal compounding, though the formal FDA rule is still pending. Even so, 503A compounding with a doctor's prescription is broadly considered permitted as of April 2026. A 503A pharmacy makes patient-specific compounded drugs; a 503B facility compounds in bulk for clinics.

Standard dosing: 1.6 mg under the skin twice a week. That matches the approved Zadaxin hepatitis B protocol of 1.6 mg twice weekly for 26–52 weeks. Wellness users typically cycle 2–3 months on, then 1 month off.

Uses: Immune support, chronic infections, post-treatment Lyme, chronic fatigue (CFIDS), hepatitis B and C, cancer adjunct, COVID recovery, autoimmune modulation, and vaccine adjuvant. Insurance does not cover Tα1 for off-label or wellness use in the US. Off-label means a use FDA has not approved.