PepsRadar
⌕ Search✧ Ask
Despite the shared name, these are unrelated proteins with different jobs. Thymosin alpha-1 (thymalfasin) is an immune peptide approved in many countries but not by FDA. Thymosin beta-4 is a 43-amino-acid protein that helps organize the cell’s internal skeleton and is studied for tissue repair.
| Fact | Thymosin alpha-1 | Thymosin beta-4 |
|---|---|---|
| FDA status | Not FDA-approved | Not FDA-approved |
| What it is | Thymosin alpha-1, also called thymalfasin, is investigated for immune-related effects. The clinical value of immune modulation depends on the disease and endpoint. | Thymosin beta-4 is a full-length 43-residue peptide studied in tissue biology. The selected human study tested an ophthalmic preparation for dry eye, with negative primary endpoints. |
| Human evidence | No randomized trials · phase 3 trial | 2 randomized trials |
| Human safety data | Very limited. Approved in many countries outside the US but not FDA-approved. Trials report good tolerability, mainly injection-site irritation; FDA calls compounded-product safety information inadequate. | Trials only. Investigational protein, not FDA-approved. Small trials of eye drops and infusions reported mostly mild side effects, but long-term and whole-body safety remain unknown. |
| Boxed warning | No FDA label to carry one | No FDA label to carry one |
| Serious risks |
| None listed |
| Conditions flagged | None flagged, because there is too little human safety data to assess | Cancer, now or in the past |
| Claim check | Partly supported: Thymosin alpha-1 boosts the immune system and prevents infections. | False: TB-500 is the same thing as thymosin beta-4 and works the same way. |
Each row comes from the Thymosin alpha-1 and Thymosin beta-4 profiles, where every fact links to its source. “Conditions flagged” lists the health conditions each profile’s Risks & interactions section mentions.
Human phase 3 trial · 1,106 adults with sepsis randomized across 22 centers in China.
Twenty-eight-day mortality was 23.4% versus 24.1%; hazard ratio 0.99 (95% CI 0.77–1.27). No clear mortality benefit was demonstrated.
Limitation: A large negative overall result should not be replaced by favorable subgroup headlines. Sepsis treatment also differs substantially from immune-enhancement claims in healthy people.
Human randomized trial · 72 people with moderate to severe dry eye.
Neither primary endpoint—ocular discomfort nor inferior corneal staining at day 29—showed a statistically significant treatment benefit. Some secondary outcomes favored treatment.
Limitation: Secondary findings should be interpreted alongside failure of the primary endpoints. The ophthalmic route and dry-eye population do not establish safety or efficacy of systemic use.
Human phase 2 randomized trial · Nine patients with severe dry eye; the abstract reports outcomes for 12 treated eyes and six control eyes.
At day 56, the reported reductions relative to vehicle were 35.1% for ocular discomfort and 59.1% for total corneal fluorescein staining. Treatment was described as well tolerated.
Limitation: Very small sample and multiple assessment times limit confidence. Read beside the larger 72-person trial, which missed its primary endpoints. Ophthalmic findings do not establish systemic injury recovery or equivalence to TB-500 fragments.
Results from different trials are not a head-to-head comparison: the people, preparations, durations and measures differ.
Neither is FDA-approved, and the trials summarized here do not show the broad immune-boosting or healing effects they are marketed for.
PepsRadar does not give doses or usage instructions, and this page is not medical advice. For a prescription medicine, talk to your prescriber or pharmacist.
Other comparisons: BPC-157 vs TB-500 · Semaglutide vs Tirzepatide · Tirzepatide vs Retatrutide · CJC-1295 vs Ipamorelin · Sermorelin vs Tesamorelin · Selank vs Semax · MOTS-c vs Elamipretide · Ipamorelin vs MK-677 · AOD-9604 vs HGH Fragment 176-191 · Tesamorelin vs CJC-1295 · GHK-Cu vs AHK-Cu · Epitalon vs Pinealon
See something wrong on this page? Report a mistake · Corrections