Reviewed by the PeptideMind Team · Updated July 15, 2026

Thymalin Dosage Guide, Benefits & Side Effects

Thymalin, approved in Russia (not FDA), restores T-cell immunity; one trial in older COVID-19 patients showed nearly half the mortality risk.

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Thymalin Dosage Guide for Immune & GutThymalin Dosage Calculator

Thymalin helps restore balance to the immune system and is given as an injection under the skin.

Vial size

20 mg

Bacteriostatic water

2 mL

Dosing

10 mg

Frequency

Daily

Cycle

5–10 days

Benefit

Immune & Gut

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Basic Dosage Calculator

Calculate peptide doses with our visual syringe guide.

Peptide per vial

Target research quantity

Bac water added

What is Thymalin?

Thymalin is a natural peptide extract taken from the thymus glands of young calves, used to support immune function. It's been an officially registered medication in Russia and Eastern Europe since 1982, with over four decades of clinical use for immune deficiencies, infections, cancer support, and age-related immune decline. It works by helping key immune cells mature properly and by balancing the signaling molecules (cytokines) that coordinate the immune response.

Longevity

Research targets include cellular aging, senescence, and long-term healthspan.

Immunity

Research targets include immune cell activity, inflammatory response, and infection defense.

Immunity

thy

Immunity

Is Thymalin FDA approved?

Thymalin is not an FDA-approved drug. It is intended for research purposes only and is not approved for human consumption, diagnostic, or therapeutic use.

Research Use Only

Thymalin has not been evaluated by the FDA for safety or efficacy in humans.

No Clinical Oversight

Not manufactured under FDA-regulated quality or clinical standards.

Unregulated Sourcing

Purity, dosing, and sourcing are not verified through FDA testing or oversight.

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How Does Thymalin Work?

Its small peptide pieces bind directly to DNA and the proteins that package it inside immune cells, helping regulate genes that control which immune cells mature, how they communicate with signaling proteins, and how new blood cells are produced. This helps normalize immune function that depends on a healthy thymus gland.

Binds DNA in immune cells

Small peptide pieces bind directly to DNA and its packaging proteins.

Regulates immune genes

Helps regulate which immune cells mature and how they communicate.

Normalizes immune function

Supports healthy function that depends on a healthy thymus gland.

How to reconstitute Thymalin

View guide

The materials you'll need and step-by-step instructions for safely mixing Thymalin with bacteriostatic water.

Materials needed

Your Thymalin vial (lyophilized)

Alcohol swabs

Bacteriostatic sterile water

3 mL syringes (Luer Lock tip)

25G or 27G needles (Luer Lock). Other gauges may also be acceptable.

Sharps container (optional)

Remove the caps

Remove the caps from both your Thymalin vial and your bacteriostatic water vial.

Sanitize the rubber stoppers

Wipe down the rubber stoppers on both vials with alcohol swabs and let them dry for about 3 minutes.

Attach the needle

Take your 3 mL syringe and needle. Twist the needle's plastic hub into the Luer Lock tip on the syringe to secure it.

Draw the bac water

Pull back on the plunger to draw your desired volume of bacteriostatic water. If you overfill, just push the excess back in until you reach the right marker on the syringe.

How much bac water? Thymalin typically comes in a 20 mg vial. We recommend 2 mL of bacteriostatic water, though anywhere between 1 mL and 3 mL is acceptable. For larger vials you can use up to 5 mL — more bac water makes microdosing easier, but insulin needles usually max out at 1 mL per injection. That means a lot of bac water might force you into multiple injections to hit your target dose. Unless you're microdosing, 2 mL per vial is a solid rule of thumb.

Insert the needle into the Thymalin vial

With the bac water in your syringe, insert the needle into the Thymalin vial at a slight angle to avoid pressure buildup.

Use a thin needle: Stick to 25G or higher to avoid damaging the rubber stopper. Higher gauge means a thinner needle.

Release the water gently

Let the water run gently down the side of the vial. Don't inject it forcefully.

Heads up: Sometimes the plunger pushes itself in as soon as the needle enters the vial. Hold the plunger back so you have full control over how fast the bac water enters.

Swirl to dissolve

Avoid shaking. Gently swirl, flip, and roll the vial to dissolve the powder.

Be patient: This usually takes 2 to 5 minutes of consistent swirling, mixing in a circular motion, and gently flipping the vial up and down. The water needs to run through the powder many times to fully dissolve it. Don't shake or get aggressive with it.

Check for full dissolution

The solution should be clear with no visible particles. If it's cloudy or clumpy, wait a minute and repeat the swirling step.

Cap, dispose, and store

Once you're done, cap the needle and dispose of it (ideally in a sharps container). Store the reconstituted Thymalin vial in the fridge whenever it's not in use. It will stay good for approximately 30 days.

How to Store Thymalin

Keep the dry powder well below freezing, protected from light, for up to two years. Once mixed with liquid, refrigerate and use within 1–4 weeks, avoiding repeated freezing and thawing.

Lyophilized Storage

Desiccated at -18°C or below, protected from light, stable 12–24 months.

Reconstituted Storage

Refrigerate at 2–8°C, use within 7–28 days.

Handling Notes

Avoid freeze-thaw cycles.

A smartphone displaying a "Storage Guide" for peptides, indicating a safe storage temperature range of 2–8°C, with warnings to keep away from light, heat, and freezing. The background is light blue, and additional tips on protecting the peptides are visible below the temperature range.

What Are the Benefits of Thymalin?

What research says it may help with, and how it works in the body.

immune support

: It helps immune cells called T-cells mature and become active, supporting an overall recovery of the immune system.
: It speeds up the recovery of several types of white blood cells that make up the immune system's defense network.
: Elderly patients who used it got sudden respiratory illnesses (like colds and flu) two to two-and-a-half times less often.

longevity

: It helps bring basic body functions back into balance and supports the heart, hormone, immune, and nervous systems.
: When used together with another peptide called Epithalamin over six years, the death rate was about four times lower than in people who weren't treated.
: Clinical studies found that treated elderly people were about half as likely to die over a 6-to-8-year period as those who weren't treated.

therapeutic applications

: In patients with severe COVID-19, it helped low white blood cell counts and other immune markers recover more quickly.
: It helps restore normal function to the thymus, an immune gland that naturally weakens with age.
: In animal studies of a type of cancer called sarcoma, tumors stopped growing or shrank in more than half of the animals.

What Are the Side Effects of Thymalin?

Who should avoid it, warning signs to watch for, and what to know before combining it with other compounds.

Who Should Avoid It

: Autoimmune diseases (use with caution)
: Organ transplant recipients (immunosuppression needed)
: Pregnancy or breastfeeding
: Known hypersensitivity

Stop Right Away If You Notice

: Signs of allergic reaction
: Unusual immune responses

Milder Signs to Watch For

Discolored powderCloudy or particulate solutionBroken seal

Was it helpful?Yes

How Long Should a Thymalin Cycle Last?

This breaks down how long a typical Thymalin cycle runs and what research suggests happens at each stage. Research shows that staying on a peptide continuously, without a break, may make it less effective over time.

That's why most research protocols build in a break between cycles, often called a washout period, to let the body reset before starting again.

Day 1-5: Initial immune modulation begins
Day 5-10: T-cell activation and differentiation enhanced
Week 2-4: Improved immune markers on blood tests
Month 1-3: Reduced illness frequency
Week 0-0: Geroprotective benefits with annual cycles

Cheat Sheets Featuring Thymalin

See how Thymalin fits into a broader research stack with these free downloadable cheat sheets. Each one includes reference dose ranges, dosing frequency, and half-life for every peptide it covers. For research purposes only.

View all

Immunity Peptide Cheat Sheet

15 peptides

Longevity Peptide Cheat Sheet

42 peptides

Master Peptide Cheat Sheet

78 peptides

Thymalin Research References

It is an approved compound

4Research references

Thymalin

Thymalin is an approved compound

Peptides of Pineal Gland and Thymus Prolong Human Life

6-8 year study showed 2.0-2.1 fold mortality reduction with Thymalin; 4.1-fold when combined with Epithalamin.

n.d.

Peptide Drug Thymalin Regulates Immune Status in Severe COVID-19 Older Patients

Faster lymphopenia reversal and improved recovery of CD4+, CD3+HLA-DR+, B-cells, and NK-cells in COVID-19.

n.d.

Effect of Thymalin on Tumor and Thymus in Activation Therapy

Antitumor effects with tumor growth arrest in >50% of animals; growth suppressed by 78% in others.

n.d.

The Use of Thymalin for Immunocorrection and Molecular Aspects of Biological Activity

Detailed molecular mechanisms of Thymalin's immunoprotective action through peptides KE, EW, EDP binding to DNA and histones.

n.d.

Frequently Asked Questions About Thymalin

Straight answers on reconstitution, dosing, and safety, everything you need to research with confidence. For research reference only.

Thymalin is a polypeptide complex originally extracted from the thymus glands of young calves. It was developed at the USSR Institute of Gerontology in the 1970s and has been used in Russia since the 1980s as an immunomodulator. Unlike single-sequence peptides such as Thymosin Alpha-1, Thymalin is a mixture of multiple low-molecular-weight peptide fractions, which is why it is often described as acting on several immune pathways at once rather than one specific target.

In research and in its historical clinical use, Thymalin has been studied for supporting thymus function and immune regulation, particularly in older adults or in cases of age-related immune decline. It is also frequently discussed in longevity research contexts, often paired with the pineal peptide Epitalon, based on older Russian cohort studies reporting reduced mortality in aged populations given thymic and pineal peptide preparations. These findings come from a limited, older body of literature and have not been replicated to modern regulatory standards.

Protocols described by vendors and older clinical literature typically use intramuscular or subcutaneous injection, commonly in the range of about 1-20 mg per day for a short course of roughly 3-10 consecutive days, sometimes repeated after an interval of 1-6 months. Reported dosing varies by source and intended purpose, and there is no single standardized protocol validated for human therapeutic use outside of its historical approval in Russia.

Lyophilized (freeze-dried) Thymalin vials are generally recommended to be stored refrigerated at about 2-8°C (36-46°F), protected from light, in their original packaging until reconstitution. Once mixed with bacteriostatic or sterile water, sources commonly advise using the solution promptly, as reconstituted peptide is described as losing stability within a short window (often cited as 1-2 hours) rather than being stored overnight, though practices vary and this is not rigorously standardized information.

Available sources describe Thymalin as having a relatively mild reported side-effect profile compared to some other peptides, with mild injection-site reactions being the most commonly mentioned issue. Occasional reports of restlessness or mood changes appear in some secondary sources. It is generally advised against use in pregnancy or breastfeeding. Because Thymalin has not undergone modern controlled human safety trials, this information reflects limited and largely anecdotal or older clinical reporting rather than a well-characterized safety profile.

No. These are related but distinct thymic peptide products that are frequently confused. Thymalin is a multi-peptide calf thymus extract; Thymulin is a specific nonapeptide with a defined sequence; and Thymosin Alpha-1 is a synthetic, well-characterized 28-amino-acid peptide with broader international regulatory recognition. Their differing composition means research findings and reported effects for one should not be assumed to apply to the others.

Thymalin has regulatory approval as a medicine in Russia but does not have FDA approval or equivalent approval in the US, EU, or most other countries. In the US it is commonly sold by peptide vendors labeled 'for research use only, not for human consumption,' meaning it is not sold or intended as an approved drug, supplement, or treatment. Buyers should be aware that research-labeled products are not regulated for purity, dosing accuracy, or safety the way approved pharmaceuticals are.

Yes. The most commonly discussed combination in longevity-focused sources is Thymalin with Epitalon, referred to by some as a 'Khavinson protocol,' based on older Russian research pairing thymic and pineal gland peptide extracts. Some sources also note that Thymalin's activity may depend on adequate zinc status, since zinc is involved in thymic hormone activity. These claims are drawn from a narrow set of older studies and vendor content rather than robust, independent clinical trials.

Thymalin Dosage Guide, Benefits & Side Effects

Thymalin Dosage Guide for Immune & GutThymalin Dosage Calculator

What is Thymalin?