Thymulin Peptide: Thymus Hormone Research Explained
Thymulin peptide is a natural hormone made only by cells in the thymus. It is a chain of nine amino acids that needs zinc to work, and it was found in the early 1970s. It is not the same as Thymalin. The only treatment trials in people used a lab-made form, nonathymulin, in 1987 and 1989.
Sources: PubMed 19236333 (2009); PubMed 3310925 (1987); PubMed 2618585 (1989)
Short answer
- What is thymulin?
- A thymus hormone tied to how T cells mature. It was once called FTS, and zinc gives it its activity.
- Is it Thymalin?
- No. Thymalin is a peptide mix extracted from the thymus. Thymulin is one defined hormone.
- What did human trials find?
- Some benefit in two 1987 arthritis trials, and no benefit in a 1989 multiple sclerosis trial. No newer treatment trial in people was found.
Sources: PubMed 2657247 (1989); PubMed 33237528 (2020); PubMed 3310925 (1987); PubMed 2618585 (1989)
What Thymulin Is
Thymulin is a hormone made only by the lining cells (epithelial cells) of the thymus, a chain of nine amino acids bound to zinc, as a 2009 review (PubMed 19236333) describes it. It is a chain of nine amino acids joined to zinc. The zinc is what makes it active.
It was found in the early 1970s and was first called FTS. A 1989 review, now over 35 years old, calls it a peptide that holds a metal. It says thymulin helps T cells mature and boosts several T cell jobs. A 2009 review ties it to T cell growth inside and outside the thymus.
Researchers also use it as a marker. A 2020 study in rural Nepal measured thymulin in 290 children aged 9 to 13. It used the level as a stand-in for the size and work of the thymus.
Sources: PubMed 19236333 (2009); PubMed 2657247 (1989); PubMed 31475652 (2020)
What Is Thymalin Peptide, and How Is It Different?
Thymalin is a different substance from thymulin: a 2020 paper from a Russian group (PubMed 33237528) describes it as a mix of peptides taken from the thymus, not a single hormone. The group says it helps control the immune system. A 2023 paper from that group names two small peptides, KE and EW, as its active parts.
| Name | What it is | Where it comes from | Human record |
|---|---|---|---|
| Thymulin | A natural thymus hormone: a nine amino acid peptide bound to zinc | Made only by thymic epithelial cells | Measured in blood in people; not given as a treatment |
| Nonathymulin | A synthetic thymic peptide hormone | Made in a lab | Two arthritis trials (1987) and one multiple sclerosis trial (1989) |
| Thymalin | A polypeptide complex isolated from the thymus | Extracted from thymus tissue; KE and EW dipeptides named as its active substances | Papers come from one Russian group |
The Thymalin papers, including those on COVID-19, come from the same Russian institute. So they are not outside tests. For a different thymus-related peptide, see our thymosin alpha-1 profile.
Sources: PubMed 33237528 (2020); PubMed 37686182 (2023); PubMed 19236333 (2009)
Thymulin and Zinc
Thymulin needs zinc to work, and a 2021 rat study (PubMed 32363520) found 61% lower thymulin activity in rats fed less zinc. That is why it is studied as a zinc marker. In that study, rats fed less zinc had 61% lower thymulin activity in the blood. Their blood zinc was 31% lower than in rats with enough zinc.
The same link shows up in people. A 1993 study looked at patients with Crohn's disease. Zinc was the treatment, not thymulin.
The 1993 Crohn's disease study (PubMed 8364132) reports that plasma thymulin activity and zinc rose significantly only at:
200 mg a day of zinc sulfate (ZnSO4)
Disclaimer: this is a dose from a 1993 study, not label information and not a recommendation. Dose decisions belong with a licensed clinician.
Sources: PubMed 32363520 (2021); PubMed 8364132 (1993)
Does Thymulin Decline With Age?
Thymulin does decline with age in the studies found: a 1990 study (PubMed 2332483) measured lower active thymulin in older people and in people with Alzheimer type dementia. That study is now over 35 years old, and we know it only from its abstract.
A 2026 laboratory study describes thymulin as a thymus peptide that declines with age, and reports that it calms inflammation signals by blocking a switch called NF-kB. That work was mechanistic, done in animal tumor models rather than a human treatment trial.
Sources: PubMed 2332483 (1990); PubMed 42481458 (2026)
The Human Trials of Nonathymulin
The only human treatment trials of thymulin tested a lab-made form called nonathymulin, in two 1987 rheumatoid arthritis trials (PubMed 3310925) and one 1989 multiple sclerosis trial (PubMed 2618585). None was a safety study.
The 1987 rheumatoid arthritis trial report (PubMed 3310925) compares three dosage schedules of nonathymulin:
1 mg a day
5 mg a day
10 mg a day
Disclaimer: these are doses from 1987 trials, not label information and not a recommendation. Thymulin has no approved dose. Dose decisions belong with a licensed clinician.
The two rheumatoid arthritis trials compared the drug with a placebo, a dummy treatment. Neither patients nor doctors knew who got which. The 5 mg dose worked best. 56% of patients improved, against 17% on placebo.
The 1989 multiple sclerosis study had 40 matched patients. They got nonathymulin shots under the skin or placebo for 6 months. Then they were followed for 6 more months. The authors found nonathymulin did not work for this kind of multiple sclerosis.
Sources: PubMed 3310925 (1987); PubMed 2618585 (1989)
Newer Animal and Lab Work
Since the 1980s, thymulin research has moved to lab and animal models, with a 2019 pain study, a 2020 asthma gene therapy study and a 2026 cancer study. None of these is a human result.
- Pain (2019): a substance called CFA was used to cause swelling. Thymulin cut heat pain and paw swelling.
- Asthma (2020): in a lab model of allergic asthma, a thymulin gene therapy brought lung swelling, scarring and breathing mechanics back to normal. That was gene therapy, not thymulin shots.
- Cancer (2026): thymulin helped T cells fight tumors and improved tumor control and survival. It also made tumors respond better to a cancer drug type called anti-PD-L1. The effect depended on age.
For other peptides studied on the immune system, see our guide to peptides for autoimmune conditions.
Sources: PubMed 30851702 (2019); PubMed 32577505 (2020); PubMed 42481458 (2026)
Common Questions
What is Thymalin peptide?+
Thymalin is a mix of peptides taken from the thymus. A Russian research group says it helps control the immune system. A 2023 paper from that group names two small peptides, KE and EW, as its active parts. It is different from thymulin, which is one hormone of nine amino acids bound to zinc.
What is thymulin peptide?+
Thymulin is a hormone made only by lining cells in the thymus. It is a chain of nine amino acids joined to zinc. The zinc is what makes it active. It was found in the early 1970s and was once called FTS.
Is thymulin the same as thymalin?+
No. Thymulin is one defined hormone, a nonapeptide bound to zinc. Thymalin is a mix of peptides taken from thymus tissue. The names look alike, and some sellers list them on the same product page, but the papers describe them as different substances.
Has thymulin been tested in humans?+
A lab-made form, nonathymulin, was tested in the 1980s. Two 1987 rheumatoid arthritis trials found 5 mg a day worked best. 56% of patients improved, against 17% on placebo. A 1989 multiple sclerosis trial found it did not work. No current trial was found on ClinicalTrials.gov. Disclaimer: 5 mg is a 1987 trial dose, not a recommendation; dose decisions belong with a licensed clinician.
Does thymulin decline with age?+
A 1990 study found lower levels of active thymulin in older people and in people with dementia. A 2026 laboratory study, done in animal models, also describes thymulin as a thymus peptide that declines with age.
What does zinc have to do with thymulin?+
Thymulin needs zinc to work. In rats fed less zinc, thymulin activity in the blood was 61% lower. In a 1993 Crohn's disease study, thymulin activity rose only in patients given 200 mg a day of zinc sulfate. Disclaimer: that is a 1993 study dose, not a recommendation; dose decisions belong with a licensed clinician.
Is thymulin FDA approved?+
No FDA label for thymulin was found, and ClinicalTrials.gov lists no thymulin treatment trial. The human trials of nonathymulin date from 1987 and 1989.
Sources: PubMed 33237528 (2020); PubMed 19236333 (2009); PubMed 3310925 (1987); PubMed 2332483 (1990); PubMed 32363520 (2021); PubMed 8364132 (1993)
Related reading
This guide is for educational purposes only and is not medical advice. It describes what published reviews, 1980s trials and animal and lab studies report about thymulin. No FDA label for thymulin was found. Talk to a qualified healthcare professional before making any decision about your health.