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Immune
Immune-modulating peptide approved in dozens of countries.
Immune
A 28-amino-acid neuropeptide that relaxes blood vessels and calms inflammation.
Thymosin Alpha-1 is not FDA-approved and rated 4/5 for evidence; VIP is not FDA-approved and rated 3/5. Thymosin Alpha-1 has more human evidence behind it. Both are used for immune goals.
| Compare | Thymosin Alpha-1 Immune-modulating peptide approved in dozens of countries. | VIP A 28-amino-acid neuropeptide that relaxes blood vessels and calms inflammation. |
|---|---|---|
| Category | Immune | Immune |
| Evidence | 4/5Multiple RCTs in hepatitis and sepsis; mixed results in sepsis (large trial neutral). | 3/5Real human data (ED approval in the UK, small lung studies, a large COVID RCT that failed). CIRS nasal use is small open-label work only. |
| FDA status | Not FDA-approved (approved in ~35 other countries) | Not FDA-approved |
| WADA (sport) | Not on the Prohibited List | Not on the Prohibited List |
| Also known as | Tα1, Thymalfasin, Zadaxin | Vasoactive intestinal peptide, Aviptadil, Zyesami |
| How it works | Enhances T-cell maturation and dendritic cell function, modulating innate and adaptive immunity. | Binds VPAC1 and VPAC2 receptors. That relaxes smooth muscle in vessels and airways, reduces inflammatory cytokines and shifts immune cells toward a calmer profile. It breaks down within minutes in the blood. |
| Half-life | About 2 hours | About 2 minutes in blood |
| Commonly reported doses |
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| Route | Subcutaneous | Intranasal (spray) |
| Good once mixed | ~14 days in the fridge | ~14 days in the fridge |
| Top side effects |
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| Lowest research-listing price per mg | $2.40 (10 mg vial, 40% off) | $3.00 (10 mg vial, 40% off) |
| Latest lab purity | 99.92% (lot THA0001) | 99.90% (lot VIP0002) |
Want a third? Add another peptide. Doses are commonly reported ranges, not recommendations.
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Thymosin Alpha-1 is not FDA-approved and rated 4/5 for evidence; VIP is not FDA-approved and rated 3/5. Thymosin Alpha-1 has more human evidence behind it. Both are used for immune goals.
Thymosin Alpha-1: Not FDA-approved (approved in ~35 other countries). VIP: Not FDA-approved. Regulations change, so confirm with the FDA.
Thymosin Alpha-1 is rated 4 out of 5: Multiple RCTs in hepatitis and sepsis; mixed results in sepsis (large trial neutral). VIP is rated 3 out of 5: Real human data (ED approval in the UK, small lung studies, a large COVID RCT that failed). CIRS nasal use is small open-label work only. The scale is explained on our methodology page.
Thymosin Alpha-1 is not named on the WADA list, though the general rule on non-approved substances (S0) can still apply. VIP is not named on the WADA list, though the general rule on non-approved substances (S0) can still apply.