Thymosin Alpha-1 vs Thymalin
There is no winner on this page. What is set side by side is the published record behind each one, which is the part the two are rarely compared on.
Both in Immune and thymic
Both have a real registration and a real trial literature, and in both cases the two documents are about different things. Thymosin alpha-1's Italian label covers adjuvanting influenza vaccination in immunocompromised patients while the trials people cite are sepsis and hepatitis, and the two largest placebo controlled ones came back null. Thymalin's label lists injection into a muscle and no other route, every published human dose went that way, and no human study giving it under the skin was found. Neither drifted much on quantity; the drift is in what the paperwork actually covers.
| Field | Thymosin Alpha-1 | Thymalin |
|---|---|---|
| What a trial gave | 1.6 mg under the skin, twice weekly, and every 12 hours in sepsisThe Italian label's own dosing table, 900 micrograms per square metre of body surface | 10 mg a day for 5 to 10 days, injected into a muscleThe Russian label, and every published human use I could open across 25 years |
| What circulates | 1.6 mg under the skin, twice weekly | 10 mg a day for 5 to 10 days, injected under the skin |
| The gap | Lands on a studied dose | Lands on a studied dose |
| How long it lasts | Below three hours, with a peak at one to two hours, measured in nine healthy volunteers given 900 micrograms per square metre of body surface under the skin in 1999. The Italian label puts the peak at six hours instead, and I could not reconcile the two figures against each other. | I could not find one, in any species. My searches returned no pharmacokinetic study of thymalin by any route, which is the kind of study that measures where a dose goes and how fast it disappears, and for an extract with no defined molecule there is no single analyte to measure anyway. |
| Route studied | Under the skin in every human trial I found, and into a muscle or under the skin on the Italian label. The sepsis trial gave 1.6 mg every 12 hours for seven days, the hepatitis trials 1.6 mg twice weekly, and the registered vaccine schedule is one vial twice weekly for four weeks from the first vaccination, repeated from week eight to week twelve for the second. | Into a muscle, in every human study I could open: 10 mg daily for 10 days in the geroprotection cohort and in the Chita COVID-19 trial, and 10 mg daily for 5 days in the St Petersburg COVID-19 study. I searched PubMed for thymalin and subcutaneous and got 8 records; one 1998 paper gives thymalin under the skin to CBA mice and broiler chickens and reports it stimulated the immune response only at the injection site. |
| Route used | Under the skin, at home, twice weekly. That matches the trials and the label. What does not match is who is doing it and why. | Under the skin, at home. The label lists injection into a muscle and no other route, and I found no published human study giving thymalin under the skin. |
| Vial sizes | 1.6, 2 mg | 10 mg |
The distance, stated
Lands on a studied dose
Thymosin Alpha-1
The number is right and the reason for it is not what sellers say. 1.6 mg is not a chosen dose: the Italian label sets 900 micrograms per square metre of body surface area and prints a height and weight table, and every row of that table is that figure times the patient's surface area, to the nearest 10 micrograms. An average adult lands at 1.6 mg, which is a vial size. The drift is indication and population. The label covers adjuvanting influenza vaccination in immunocompromised patients, the trials people cite are hepatitis and sepsis, and every completed trial I found that measured whether people got better enrolled patients rather than healthy adults.
Lands on a studied dose
Thymalin
Nothing drifted on quantity and everything drifted on route. Ten milligrams sits inside the label's own 5 to 20 mg range, is one whole vial, and is the dose in all five published human uses I could open, with the course arithmetic landing inside the label's 30 to 100 mg range too. The label lists injection into a muscle and no other route, every human dose I found in a paper went that way, and I found no published human study giving thymalin under the skin. One vendor protocol page prints 30 units and calls it about 30 micrograms; thirty units is 0.3 mL, and a 10 mg vial made up in the 1 to 2 mL the label specifies holds 3 mg or 1.5 mg in that volume.
What people get wrong
Thymosin Alpha-1
The costly mistake is reading one document as though it licensed the other. A real registration exists and a real trial literature exists, and vendor pages weld them together. The registration is Italian and covers flu vaccination in immunocompromised patients. The trials are sepsis and hepatitis, and the two largest placebo controlled ones came back null: 28 day deaths of 23.4 percent against 24.1 in 1,106 septic adults, and hepatitis C cure rates of 12.7 against 10.5 percent in 552 patients. Read the corrected version of that sepsis paper, too, because the journal corrected it in place in May 2025 and the PubMed abstract still prints the old hazard ratio. Every piece of this is real. The picture assembled out of them is not.
Thymalin
Two numbers get repeated and both need reading carefully. The first is 266, which is not a trial. Khavinson and Morozov 2003 pooled three cohorts at two institutions: 94 women at a St Petersburg war veterans home randomised four ways, a separate 20 given two agents every year for six years, and 152 people in Kiev randomised three ways on a different schedule. Twenty four people received Thymalin on its own, and in that arm 10 of 24 died over six years against 18 of 22 on placebo. The second is that Thymalin halved hospital mortality, which comes from one trial in Chita and from a secondary endpoint in it. That trial met one of its three primary endpoints and missed the other two, and the treated group took slightly longer to improve.
Every figure above is carried across from each compound’s entry, which is where the citations live.
All 65 compounds on one page at what circulates vs what was studied, or pick another two to compare.