Thymalin
A peptide extract of the thymus gland, the organ that trains your immune system. People run it in short courses for immune restoration and healthy aging, often paired with Epitalon, drawing on decades of Russian clinical research.
Where to buy Thymalin, cheapest first.
Prices from 2 vendors across the market. We link straight to each vendor’s product page and grade vendors on public lab data, so you’re not just chasing the lowest number.
What Thymalin actually does.
The simple version first, then a little more for the curious. No biochem degree required.
It nudges an aging or sluggish immune system back toward balance, helping the thymus produce and mature T-cells so your defenses behave more like they did when you were younger.
How it works
Thymalin is a mix of small peptides extracted from calf thymus. It acts as a bioregulator, helping mature T-lymphocytes and rebalance the ratio of immune cell types. The idea is to normalize an immune system that has drifted, not just push it in one direction.
Where it acts
It works on the thymus and the wider immune system. Khavinson's group studied it as a peptide that signals at the gene level, which is why a short course is thought to produce effects that outlast the injections themselves.
What people notice
People run it for fewer infections, faster recovery from illness, and as part of a healthy-aging routine. Because it is given in brief courses, any effects are judged over weeks and months, not the day of a dose.
Honest caveat: much of the supporting evidence comes from Russian clinical research from the 1980s onward and from animal studies, and it has not been replicated in large independent Western trials. It is not an approved medicine in the US and is sold strictly for research use only. None of this is medical advice, talk to a licensed provider before starting anything.
How to take it.
Thymalin is an injection, given as a short course of daily intramuscular shots, with subcutaneous used as a gentler alternative. It is supplied as a freeze-dried powder you reconstitute fresh. The routine is below; for course length and timing, see the full guide.
Reconstitute the vial
Add bacteriostatic water down the side of the vial (a 10mg vial + 1mL = 10mg/mL). Swirl gently until dissolved, don't shake. Many people mix fresh each day since reconstituted thymalin isn't meant to be stored long.
Draw your dose
On a U-100 insulin syringe, pull to your unit mark. 10mg at 10mg/mL is 100 units (1mL). For a 5mg dose draw 50 units. Use the calculator if you're unsure.
Set the Z-track and inject
Swab with alcohol, pull the skin to one side (Z-track), insert at 90° into muscle, aspirate, then push slowly. The upper outer buttock or the thigh muscle are the usual spots.
Run the course, then stop
Thymalin is given daily for a set number of days, then stopped, not run continuously. Rotate sides each day and store the sealed vials in the fridge.
Inject into muscle: the shoulder (deltoid), the hip (ventrogluteal), or the outer thigh (vastus lateralis). Use the Z-track method and rotate.
Don't do the math, let the calculator do it.
This is Thymalin's typical setup, already worked out. Change any value and the draw updates instantly.
Typical Thymalin dose: about 5 to 10 mg daily by intramuscular injection for a short course of 5 to 10 days, repeated once or twice a year. It is run in defined courses, not continuously.
How to cycle Thymalin.
How long people run Thymalin, when to take a break, and the honest reasoning behind it.
Short courses, repeated once or twice a year.
A cycle just means a defined run of time on the peptide, followed by a break. For Thymalin the pattern is built in: a short course of daily injections over 5 to 10 days, then off, with the course repeated once or twice a year rather than run continuously.
Why not just run it forever? Partly because the whole bioregulator idea is that a brief course is enough, and partly because the long-term human safety data outside the original Russian work is thin. The cautious, widely followed approach is the short repeated course.
- Run the full course of daily injections over your chosen 5 to 10 days at roughly the same time each day.
- Stop at the end of the course rather than drifting into open-ended daily use. The course is the unit, not the single dose.
- Space out repeats to once or twice a year. If you are using it for a specific health reason, that is a conversation for a licensed provider.
Want the full picture, on and off periods, the washout, stacking, and keeping your results? Read how peptide cycling works →
What's actually in the vial.
These link to each vendor's general lab-results page. We don't run the labs ourselves and we don't show a purity number unless it's printed on a certificate we link, so you can open the document and check it against the batch yourself.
| Vendor | Purity (per COA) | Batch / report | Certificate |
|---|---|---|---|
| Penguin Peptides | see lab page | not shown | Lab results ↗ |
What people pair it with.
Thymalin is most often run as part of a healthy-aging routine. These are the combinations the longevity community reaches for.
Immune & longevity
The classic bioregulator pairing from Khavinson's research. Thymalin works on the immune system through the thymus while Epitalon works on the pineal side. The two are run as parallel short courses in the same block.
View stack →Defense support
Two thymus-derived approaches to immune support. Thymalin is the older bioregulator extract; Thymosin α-1 is a single defined peptide. People who want a heavier immune focus sometimes run them in sequence rather than together.
View stack →Healthy aging
A longevity-leaning stack that layers immune balance, the pineal bioregulator, and a mitochondrial peptide. An ambitious routine for people focused on the aging picture as a whole.
View stack →In the same corner.
Other longevity and aging peptides people compare against Thymalin.
Questions, answered straight.
Is Thymalin legal?
Thymalin isn't an approved drug in the US, and it isn't sold for human use here. The vendors we compare offer it strictly for research use only. It has a long clinical history in Russia and CIS countries. It is not currently on WADA's prohibited list, but policies change, so competing athletes should verify before relying on that. Rules vary by country, so check what applies where you are.
What does research use only actually mean?
It means the product is sold for laboratory and research purposes, not as a supplement or medicine for people. It hasn't been reviewed or approved for human use by the FDA. We aggregate prices and public lab data so you can see the landscape; what you do with that is between you and a licensed provider.
How do I store it?
Keep the sealed, freeze-dried vials in the fridge and out of direct light. Thymalin is usually reconstituted fresh and used right away rather than stored mixed for long stretches, so only mix what you plan to inject that day.
How often do people dose it?
A common pattern is about 5 to 10 mg daily for a short course of 5 to 10 days, repeated once or twice a year rather than run continuously. The course structure matters more than any single dose. Use the calculator to turn your vial and dose into exact units.
Intramuscular or subcutaneous?
Intramuscular is the traditional clinical route and the most common. Some people use subcutaneous as a gentler alternative. After reconstitution the draw is the same either way. Thymalin isn't an oral peptide, so skip any capsule versions.