Thymosin Alpha-1 dosage
Thymosin alpha-1 is thymalfasin, sold as Zadaxin in more than 30 countries (not the US). The labeled dose is 1.6 mg subcutaneous twice a week for 6 to 12 months, the same regimen as the 1998 hepatitis B trial that supports it. Community use copies that exactly, 1.6 mg twice weekly, with some people doing 1.6 mg daily for a week during an illness. Over 2,000 patients in trials and under 1% had a drug-related side effect.
Basis: clinical trial (Chien et al. 1998, Hepatology, 98 chronic hepatitis B patients, randomized; same dose as the Zadaxin label, 900 mcg/m2). 26 or 52 weeks; no significant side effects
- How often
- twice weekly, 3 to 4 days apart
- When
- any time of day
- How long
- label: 6 to 12 months; community: 4 to 12 weeks, repeated as needed
- Route
- subcutaneous only (the label says never intravenous)
- Storage
- lyophilized: fridge (label 2 to 8 C); reconstituted: use immediately on the label, within 4 weeks refrigerated by common practice
Dose ranges by source
| Range | Per | Basis | Note |
|---|---|---|---|
| 1.6 mg twice weekly | dose | clinical trial (Chien et al. 1998, Hepatology, 98 chronic hepatitis B patients, randomized; same dose as the Zadaxin label, 900 mcg/m2) | 26 or 52 weeks; no significant side effects |
| 1.6 mg once or twice weekly | dose | commonly reported | maintenance; some do 1.6 mg daily for 5 to 7 days during acute illness, and a few report 3 to 6.4 mg, which is above any label |
Thymosin Alpha-1 dose to units chart
10 mg vial + 2 mL bacteriostatic water = 5 mg/mL (50 mcg per unit on a U-100 insulin syringe). 10 mg + 2 mL = 5 mg/mL, so 1.6 mg = 0.32 mL = 32 units. A 5 mg vial + 1 mL gives the same 32 units. The Zadaxin vial is 1.6 mg in 1 mL, one dose per vial.
| Dose | mL | Units (U-100) | Doses per vial |
|---|---|---|---|
| 1.6 mg | 0.32 | 32 | 6 |
| 2 mg | 0.4 | 40 | 5 |
Different vial or water? Full 10 mg + 2 mL table or set your own numbers below.
Side effects
- injection site discomfort or redness
- rash (rare)
- joint pain with hand swelling (rare)
- transient muscle soreness (rare)
- ALT flare during hepatitis treatment (expected on the label)
Thymosin Alpha-1 dosage questions
Thymosin alpha 1 dosage?
1.6 mg subcutaneously twice a week. That is the Zadaxin label dose, the dose in the 1998 hepatitis B trial and what most people copy. The label runs it 6 to 12 months; community cycles are usually 4 to 12 weeks.
How many units is 1.6 mg of thymosin alpha 1?
With 10 mg in 2 mL (5 mg/mL) 1.6 mg is 32 units. With 5 mg in 1 mL it is also 32 units. With 5 mg in 2 mL it is 64 units.
Can you take thymosin alpha 1 daily?
Some ICU trials gave 1.6 mg every 12 hours for a week, and community users sometimes do 1.6 mg daily for 5 to 7 days when sick. The chronic data is all twice weekly. Daily use is a short-term choice, not a maintenance plan.
Is thymosin alpha 1 FDA approved?
No. It is approved in over 30 countries under the name Zadaxin, mainly for hepatitis B, and has US orphan designations, but no US approval. The FDA has also restricted compounding of it.
Sources
- Chien RN et al., Hepatology 1998, Efficacy of thymosin alpha1 in patients with chronic hepatitis B: a randomized, controlled trial (PubMed 9581695)
- RxList, Zadaxin (thymalfasin) prescribing summary: 1.6 mg subcutaneous twice weekly, how supplied, adverse reactions
- Peptide Protocol Wiki, Thymosin alpha-1 dosing (community protocols)
Brands we recommend for Thymosin Alpha-1. We are independent and have no affiliation with any brand: no affiliate links, no referral codes, no paid placements. These are the suppliers whose testing and certificates hold up when we check them.
- Licensed Peptides two accredited labs on every lot, certificates public, card and Apple Pay checkout
- Core Peptides long track record, public certificates, wide catalog
- Ascension Peptides public third-party testing, clear pricing
This page is an educational summary of published labels, trials and commonly reported use. It is not medical advice and does not replace a clinician.