Thymosin alpha-1 (TA1)
Immune modulator registered outside the US
Experimental material. Read before using anything from here.
Nothing on this page is a medical recommendation, prescription or treatment plan. It is an organized translation of protocols circulating in research communities and, where it exists, of what published trials tested. The two are marked differently — and they are not equivalent.
Most of the compounds here have no FDA approval for human use. Several are sold labeled "research use only", which means they have not gone through purity, sterility or dosage controls for human consumption. A community-reported dose is not a validated dose: it is what someone reported having done.
Talk to a licensed health professional before considering any of these compounds. If you already use one and feel anything unexpected, seek care — do not wait for the next routine test.
Summary
28-amino-acid peptide produced naturally by the thymus. It helps train and coordinate the immune cells that fight viruses and other infections. The synthetic version, thymalfasin, is sold as Zadaxin and is registered in several countries for hepatitis B and C.
Quick reference
- Route
- Subcutaneous — abdomen, thigh or arm. Rotate the sites.
- Standard schedule
- 1.6 mg 2×/week, with a 3–4 day interval (e.g., Monday and Thursday).
- Measure
- 10 mg vial + 2 mL of bacteriostatic water (5 mg/mL): 1.6 mg = 0.32 mL = 32 units on the U-100.
- Status
- Approved as Zadaxin in more than 35 countries; not approved in the US.
Thymosin Alpha-1 Schedule
| Parameter | Value |
|---|---|
| Dose per injection | 1.6 mg |
| Frequency | 2x per week |
| Spacing | 3-4 days apart (e.g., Mon/Thu) |
| Route | SubQ |
| Typical duration | 6 months (HBV monotherapy / cancer adjunct); up to 12 months (HCV combination) |
Thymosin Alpha-1 Schedule
| Body weight | Approximate dose |
|---|---|
| 30 kg | 1.2 mg 2×/week |
| 35 kg | 1.4 mg 2×/week |
| ≥40 kg | 1.6 mg 2×/week (adult, standard) |
Cycle Guidelines
| Research context | Reported duration | Source type |
|---|---|---|
| Chronic hepatitis B (monotherapy) | 6 months | Zadaxin pooled analysis of 3 RCTs |
| Chronic hepatitis C (with interferon) | 6-12 months | Zadaxin pooled analysis (2 RCTs + 1 historical control) |
| Severe sepsis (TESTS, BMJ 2025) | 7 days continuous (every 12 hours) | Phase 3 RCT, 22 Chinese centers |
| Immune support / community use | 4-12 weeks | Community-derived, not from a clinical trial |
Thymosin Alpha-1 Reconstitution Guide
| Vial size | BAC water added | Concentration | Volume per 1.6 mg | Units (U-100 syringe) |
|---|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 0.32 mL | 32 units |
| 10 mg | 2 mL | 5 mg/mL | 0.32 mL | 32 units |
| 10 mg | 1 mL | 10 mg/mL | 0.16 mL | 16 units |
| 20 mg | 2 mL | 10 mg/mL | 0.16 mL | 16 units |
| 20 mg | 4 mL | 5 mg/mL | 0.32 mL | 32 units |
Thymosin Alpha-1 Timeline & What to Monitor
| Endpoint | When measured | Source |
|---|---|---|
| Peak plasma TA1 level | 1-2 hours post-injection | Rost et al. 1999 PK study |
| Lymphocyte / CD4+ shifts | 4-8 weeks of dosing | Multiple HBV/HCV trials |
| HBV viral load reduction | 12-26 weeks | Zadaxin pooled HBV monotherapy analysis |
| HCV sustained viral response (with interferon) | Up to 12 months post-treatment | Zadaxin combination-therapy analyses |
Thymosin Alpha-1 vs TB-500, BPC-157, and KPV
| Peptide | Mechanism | Best-supported research context | Evidence base |
|---|---|---|---|
| Thymosin Alpha-1 | TLR2/TLR9 → dendritic cells → T-cell activation | Chronic HBV/HCV, cancer adjunct, immune support | Approved in 35+ countries; decades of clinical use |
| TB-500 (thymosin beta-4 fragment) | Actin-binding peptide; cell migration and tissue repair | Soft-tissue and tendon repair (mostly preclinical) | Strong animal data; limited human trials |
| BPC-157 | Gastric pentadecapeptide; angiogenic and tissue repair | GI healing, soft-tissue repair | Strong animal data; limited human trials |
| KPV | α-MSH C-terminal tripeptide; anti-inflammatory | Gut inflammation, topical skin | Mechanism clear; small clinical footprint |
Storage and handling
The rules below apply to practically every lyophilized peptide in this reference. Where a compound has its own requirement, it appears in the table in the previous section.
- Lyophilized powder, sealed: refrigerator, between 2 and 8 °C, protected from light. Many tolerate room temperature for short transport periods, but that is tolerance, not a recommendation.
- After reconstitution: always refrigerated, between 2 and 8 °C. The stability window drops to days or a few weeks, depending on the compound.
- Never freeze after reconstituting. The freeze–thaw cycle degrades the peptide.
- Do not shake. Swirl the vial slowly. Shaking breaks the peptide chain.
- Bacteriostatic water down the wall of the vial, in a slow stream, not squirted directly onto the powder.
- Cloudy solution, with particles or a color change: discard. There is no recovery.
Lab tests and monitoring
This list is the one that appears recurrently in the source, with small variations by compound. It serves as a starting point for a conversation with a professional — not as a substitute for that conversation.
- Before starting: complete blood count, comprehensive metabolic panel, lipid panel, fasting glucose and HbA1c, TSH and free T4, blood pressure and resting heart rate.
- Depending on the compound: IGF-1 (GH axis), lipase and amylase (VIP and the incretin agonists), serum copper and ceruloplasmin (GHK-Cu and blends containing it), CRP.
- Reassessment: most protocols review between week 4 and week 8, and then every 8–12 weeks.
- Do not wait for the routine lab test in the face of abdominal pain, visual changes, a change in a mole, shortness of breath, asymmetric swelling or any new and persistent symptom. That is a reason to seek care, not a spreadsheet item.
Evidence limits
Data source: peptidedosingprotocols.com, accessed on September 3, 2026. Translation and organization in Portuguese are original work. No primary source (PubMed, trial registry, package insert) was checked in building this page — the check was against the secondary source, and that alone.