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Some human trialsNot FDA approved

Thymosin Alpha-1 dosage

Also known as: Ta1 · TA-1 · Thymalfasin · Zadaxin · Thymosin alpha 1

Updated 26 sources

Every Thymosin Alpha-1 protocol on file, 19 in all, labelled by where each number came from. 3 have titration steps, each step is worked out in U-100 units for a 1.6 mg vial + 1 mL water.

Calculate with Thymosin Alpha-1Thymosin Alpha-1 overview

Thymosin Alpha-1 dosage by goal

Grouped by goal. Each protocol shows the amount, how often, cycle and rest as the source states them, with every titration step.

Standard immune support2

Standard immune support

Amount
1.6 mg
How often
Twice weekly, e.g. Monday and Thursday
Route
SubQ, vial (powder)
Cycle
8 to 12 weeks

Standard immune support (community)

Amount
1.5 mg
How often
Twice weekly
Route
SubQ, vial (powder)
Cycle
8 to 12 weeks

Daily low dose2

Daily low dose

Amount
300 to 500 mcg
How often
Once daily
Route
SubQ, vial (powder)
Cycle
8 weeks in the chart; 8 to 16 weeks commonly reported
Titration steps for Daily low dose
WhenDoseU-100 units (1.6 mg vial + 1 mL water)
Week 1300 mcg18.8 units · 0.188 mL
Weeks 2 to 8500 mcg31.3 units · 0.313 mL

Note: Not a trial or label schedule; the label dose is 1.6 mg twice a week.

Daily low dose (community)

Amount
300 to 500 mcg
How often
Once daily
Route
SubQ, vial (powder)
Cycle
4 to 8 weeks

Other protocols: injected15

Chronic hepatitis B (label)

Amount
1.6 mg
How often
Twice a week
Route
SubQ, vial (powder)
Cycle
6 to 12 months

Who: Adults with chronic hepatitis B, where Zadaxin is approved (not the US).

Note: Label dose outside the US. Subcutaneous only, never intravenous. The 1.6 mg vial is mixed with 1 mL of the supplied sterile water just before use.

Chronic hepatitis C with interferon (label)

Amount
1.6 mg
How often
Twice a week
Route
SubQ, vial (powder)
Cycle
12 months

Who: Adults with chronic hepatitis C, alongside interferon, where Zadaxin is approved.

Under 40 kg (label)

Amount
40 mcg/kg
How often
Twice a week
Route
SubQ, vial (powder)

Who: Label patients weighing under 40 kg.

Sepsis (TESTS trial)

Amount
1.6 mg
How often
Every 12 hours
Route
SubQ, vial (powder)
Cycle
7 days

Who: 1,106 adults with sepsis in Chinese ICUs.

Note: 28-day mortality was 23.4% vs 24.1% on placebo (HR 0.97), so the trial found no clear benefit.

Hepatitis B trial

Amount
1.6 mg
How often
Twice a week
Route
SubQ, vial (powder)
Cycle
26 or 52 weeks

Who: 98 adults with chronic hepatitis B (Chien 1998).

Note: At 18 months, complete virological response was 40.6% after 26 weeks and 26.5% after 52 weeks, vs 9.4% untreated.

Acute illness, front-loaded

Amount
1.6 mg
How often
Daily for 5 to 7 days, then twice weekly
Route
SubQ, vial (powder)
Cycle
1 week of daily loading, then 4 to 8 weeks twice weekly
Titration steps for Acute illness, front-loaded
WhenDoseU-100 units (1.6 mg vial + 1 mL water)
Days 1 to 71.6 mg100 units · 1 mL
Weeks 2 to 91.6 mg100 units · 1 mL

Note: Pitched for active infections and recovery after chemotherapy. No trial tested this pattern; the twice-daily sepsis trial found no mortality benefit.

Longevity and prevention

Amount
1.6 mg
How often
Once or twice weekly
Route
SubQ, vial (powder)
Cycle
8 to 12 weeks, 2 to 3 cycles a year
Rest
4 weeks off between cycles

Label-based six-month course

Amount
1.6 mg
How often
Twice a week, 3 or 4 days apart
Route
SubQ, vial (powder)
Cycle
6 months, 52 injections

Conservative start, small frame

Amount
0.8 to 1.2 mg
How often
Twice weekly, 3 to 4 days apart
Route
SubQ, vial (powder)
Cycle
2 to 4 weeks, then step up to 1.6 mg

Short acute course

Amount
1.6 mg
How often
Once or twice daily
Route
SubQ, vial (powder)
Cycle
5 to 7 days only

Note: The guide lists this as a hospital (ICU) regimen that people copy. The largest trial of twice-daily dosing, in sepsis, found no mortality benefit.

Intensive

Amount
3.2 mg
How often
Twice weekly
Route
SubQ, vial (powder)
Cycle
6 to 12 month courses for chronic conditions

Note: One guide's tier. 3.2 mg was one of the arms in a melanoma trial alongside chemotherapy.

Low starting schedule

Amount
250 mcg
How often
3 times a week, then 500 mcg weekly to maintain
Route
SubQ, vial (powder)

Note: The same guide also lists 1.6 mg twice weekly as typical and does not explain the gap.

When sick (community)

Amount
1.6 mg
How often
Daily for 3 to 5 days, then twice weekly
Route
SubQ, vial (powder)
Cycle
2 to 4 weeks
Titration steps for When sick (community)
WhenDoseU-100 units (1.6 mg vial + 1 mL water)
Days 1 to 51.6 mg100 units · 1 mL
Days 6 to 281.6 mg100 units · 1 mL

Note: Community front-loading. The titration shows the longer end (5 daily doses, then twice weekly to week 4).

Long-term maintenance (community)

Amount
1.5 mg
How often
Once weekly
Route
SubQ, vial (powder)
Cycle
3 months on
Rest
1 month off

Note: Reported by immunocompromised users on the aggregator.

Immune loading (community)

Amount
1 mg
How often
Daily
Route
SubQ, vial (powder)
Cycle
10 to 30 days

Doses shown are what sources report, labelled by origin. Not medical advice.

Thymosin Alpha-1 dosage chart by vial size

Units to draw for the doses sources cite most, at every vial size and water volume.
Thymosin Alpha-1: concentration and U-100 syringe units for each vial size and water volume
WaterStrength300 mcgdose, units500 mcgdose, units1.6 mgdose, units
1.6 mg vial
1 mLRegulatory1.6 mg/mL18.80.188 mL31.30.313 mL1001 mL
5 mg vial
1 mLCompetitor guide5 mg/mL60.06 mL100.1 mL320.32 mL
2 mLCompetitor guide2.5 mg/mL120.12 mL200.2 mL640.64 mL
10 mg vial
1 mLCompetitor guide10 mg/mL30.03 mL50.05 mL160.16 mL
2 mLCompetitor guide5 mg/mL60.06 mL100.1 mL320.32 mL
3 mLCompetitor guide3.333 mg/mL90.09 mL150.15 mL480.48 mL
20 mg vial
2 mLCompetitor guide10 mg/mL30.03 mL50.05 mL160.16 mL
4 mLCompetitor guide5 mg/mL60.06 mL100.1 mL320.32 mL
Units are on a U-100 insulin syringe (100 units = 1 mL). U-50 and U-30 barrels read the same units.Water volumes from

Doses shown are what sources report, labelled by origin. Not medical advice.

Calculate with this peptideYour vial, your water, your dose: Thymosin Alpha-1 in syringe units, with the math shown.

Mixing Thymosin Alpha-1

Diluent: Bacteriostatic water for research vials; sterile water for the 1.6 mg Zadaxin vial

Water volumes sources use: 1 mL, 2 mL, 3 mL, 4 mL

A 10 mg vial gives about 6 doses of 1.6 mg. Inject under the skin, never into a vein. Never mix it with another drug in the same syringe.

If you miss a dose

If a twice-weekly dose is 1 to 2 days late, take it and do not double up. Then reset so the next injection falls 3 to 4 days later, and add any skipped dose to the end of the course.

Thymosin Alpha-1 dosage questions

What is the standard dose?

1.6 mg under the skin twice a week, 3 to 4 days apart. That is the Zadaxin label dose for hepatitis B (6 to 12 months) and hepatitis C (12 months), and nearly every guide anchors on it. People under 40 kg get 40 mcg/kg.

What dose do people use when sick?

Community and guide protocols front-load: 1.6 mg daily for 3 to 7 days, then twice weekly for a few weeks. No trial has tested this in otherwise healthy people. The closest test, 1.6 mg twice daily for 7 days in 1,106 sepsis patients, found no mortality benefit.

How many units is 1.6 mg?

With 10 mg in 2 mL (5 mg/mL), 1.6 mg is 0.32 mL, or 32 units on a U-100 syringe. With 10 mg in 1 mL it is 16 units. Use the calculator for your own mix.

Daily or twice a week?

The label and trials use twice a week, even though the half-life is only about 2 hours. One guide runs 300 to 500 mcg daily instead, and community users report a daily low-dose version, neither from a trial.

Sources for these doses

13 sources, each checked by date. Record updated Oct 24, 2026. Numbers are restated in our own words and labelled by where they came from.

Regulatory2

  1. Zadaxin injection (SIN07483P) product informationSingapore National Drug Formulary · checked Oct 24, 2026
  2. Zadaxin (thymalfasin) prescribing informationRxList, via a reference work · checked Oct 24, 2026

Vendor guide2

  1. Thymosin alpha-1 catalog pageVendor product page · checked Oct 24, 2026
  2. Thymosin Alpha 1 (10 mg) product pageVendor product page · checked Oct 24, 2026

Competitor guide4

  1. Thymosin Alpha-1 profilepeptidesexplorer.com · checked Oct 24, 2026
  2. Thymosin Alpha-1 dosage chartpeptidedeck.com · checked Oct 24, 2026
  3. Thymosin Alpha-1 (10 mg vial) dosage protocolpeptidedosages.com · checked Oct 24, 2026
  4. Thymosin Alpha-1 compound pagepeptiq.io · checked Oct 24, 2026

Community-reported2

  1. Thymosin Alpha-1 community protocols and reportspeptideprotocolwiki.com, via a competitor guide · checked Oct 24, 2026
  2. Thymosin Alpha-1 (TA1) guide, community commentarypeptidedosingprotocols.com, via a competitor guide · checked Oct 24, 2026

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