# Thymulin

Zinc-bound thymic nonapeptide; injected for immunity, sprayed on scalps for hair. 1980s data only.

- Page: https://peprank.xyz/peptides/thymulin
- Category: Immune (Research peptide)
- Also known as: FTS-Zn; zinc-thymulin; facteur thymique sérique (FTS); nonathymulin; serum thymic factor
- Routes: Injection / Topical
- Safety tier: Strict: Caution · Balanced: Clean · Evidence only: Clean
- Risk axes (0 none to 3 severe): Seen harm 0, Mechanism 1, Data gap 2, Silent harm 1, Product 3
- Positive: 49% of 4 graded reports glowing or positive, shrunk toward the 49% all-report average by 8 reports' weight
- Rank: #15 of 61 research peptides
- Graded reports: 4 (Positive 2, Nothing 2)
- Evidence: Small human studies — Two small double-blind rheumatoid-arthritis trials and immunodeficiency case reports from the Bach/Dardenne group in the 1980s, plus one uncontrolled 18-person topical hair series (2017); nothing modern, no approval anywhere
- Access: Grey market
- Onset: Nothing felt acutely; immune effects are judged over weeks to months, and scalp regrowth in the topical series showed at about 6 months
- Lasts: Cumulative; users run short injection courses once or twice a year, while the topical is applied daily and indefinitely
- Cost per month: About $40-50 per grey-market 10 mg vial (Oct 2026 listings); a GHK-Cu/zinc-thymulin scalp serum around $59 a bottle
- Updated: 2026-10-30

## What users report

Too few reports to judge: four first-hand accounts, three of them on multi-peptide or multi-drug stacks. Two injectors credit it. One HSV-2 user had no symptoms for over a year on a Thymalin, thymulin and TA-1 course, though a prodrome came back months later. One CIRS user had less brain fog for a year after a thymulin and Vilon course and wonders if it was placebo. A second CIRS patient two weeks into prescribed injections could not tell whether anything had changed. A hair-loss user who ran a GHK-Cu/zinc-thymulin topical for a year among several treatments cannot say it did anything. Users also mix it up with Thymalin: one HSV user's vial labelled 'Thymalin' turned out to be thymulin. Felt nothing: 2 of 4 reports; too few reports to judge.

**Effects:** fewer infections or herpes outbreaks (anecdotal, stacked); less brain fog in CIRS (anecdotal, stacked); new vellus and intermediate scalp hairs (one small open-label topical series)

**Downsides:** daily injections in the only controlled trials (1-10 mg/day subq); cost of compounded scalp foams and serums; no felt effect to confirm it is working

**Risks:** Theoretical: an immunomodulator in people with autoimmune disease or lymphoid cancer (one Reddit user with CLL was about to inject it); the 1980s rheumatoid-arthritis trials saw no flares, but the data are thin; Grey-market vials are mostly the zinc-free nonapeptide, which is inactive unless zinc binds it, and identity, sterility and endotoxin are unverified; Name confusion with Thymalin (Russian calf-thymus extract) means people may not get the molecule they think they bought

**Caveat:** Almost everything known about thymulin as a drug comes from one Paris group in the 1980s; the topical hair claim rests on a single uncontrolled series and organ-culture work. The molecule needs zinc bound to be active, and most research vials are sold zinc-free, so what people inject may do nothing. Thymuskin's Reddit reports (some regrowth, some shedding and red scalp) are about a thymus-extract product and are not counted here.

**Typical use:** No established dose. The rheumatoid-arthritis trials used 1-10 mg/day subq (5 mg best), daily for two weeks and then three times a week; grey-market courses are improvised. Topical: daily scalp spray or foam.

**Getting it:** Not approved anywhere. Sold as 10 mg research vials (often the zinc-free peptide), occasionally prescribed by functional-medicine clinics, and compounded as GHK-Cu/zinc-thymulin scalp foams and serums. Thymuskin is a different product: a thymus-peptide hair line, not pure thymulin.

**Stacked with:** Thymalin and thymosin alpha-1 (Run together as 'thymic peptides' by HSV and CIRS users, which makes thymulin's own effect impossible to separate.); Vilon, VIP, KPV (Part of CIRS protocols, with thymulin and Vilon as the short 'immune gene regulator' course.); GHK-Cu (topical) (The usual commercial scalp pairing, sometimes with PTD-DBM, alongside or instead of minoxidil.)

## Risk profile

- **Seen harm 0/3:** No serious adverse events reported: the 1980s rheumatoid-arthritis trials described minimal adverse effects, the 18-person topical series none over 3,300 treatment days, and the handful of Reddit users nothing serious. The zero reflects very little human exposure, not reassurance.
- **Mechanism 1/3:** Thymulin drives T-cell differentiation and restored cell-mediated immunity in immunodeficient children, so immune stimulation in autoimmune disease or lymphoid cancer is a theoretical worry. In vivo, though, its actions are mostly anti-inflammatory and analgesic, and it improved rheumatoid arthritis without flares. Its pituitary-hormone effects are shown only in vitro and in animals. Speculative rather than credible at the doses used.
- **Data gap 2/3:** Small human studies only: two 1980s rheumatoid-arthritis RCTs and case reports from one Paris group, and one uncontrolled 18-person topical series. No approval anywhere and nothing modern. The trials used synthetic zinc-thymulin, the same molecule sold today, though most vials are sold zinc-free.
- **Silent harm 1/3:** The harms most plausible for what people actually inject are injection-site and contamination reactions and a flu-like flare, all noticed within days. A slower immune effect, such as an autoimmune flare, would mostly show as symptoms but could take weeks to appear.
- **Product 3/3:** Most users buy grey-market injectable 10 mg research vials, often the zinc-free peptide, with unverified identity, sterility and endotoxin. Thymalin/thymulin label confusion adds identity risk. Compounded GHK-Cu/zinc-thymulin scalp foams from pharmacies (1) are the minority channel.
- **Never if:** Pregnancy or breastfeeding (no human reproductive data); Organ transplant or other immunosuppressive therapy; Lymphoid cancers such as CLL or lymphoma, where T-cell stimulation is untested

## Top reports

- Positive, immune: “Since using thymic/immune peptides (from a reputable supplier) - specifically Thymalin, Thymulin, and TA-1 -- I have absolutely nothing, not even the tiniest symptom, for more than a year.” — [r/Herpes](https://www.reddit.com/r/Herpes/comments/1puobvz/personal_experience_with_immune_peptides/)
- Positive, immune: “Anecdotally they have had long lasting benefits as I did a course 1 year ago and I’ve had less brain fog since, but I don’t know how much of it is placebo or in general and increase in my health as a whole because there are so many other factors.” — [r/CIRS](https://www.reddit.com/r/CIRS/comments/1v3oxvz/peptides_for_cirs/oz4ueun/)
- Nothing, skin-hair: “Was super expensive and I dont remember if they worked or not. Cost me about 1K per month. Topical Dutasteride worked for sure but unsure about the rest” — [r/tressless](https://www.reddit.com/r/tressless/comments/1hocdph/thoughts_on_a_previous_stack_m/)
- Nothing, immune: “Its difficult because I'm so brain foggy but I guess i misunderstood thymulin is meant more to stop infections and support the immune system not nessecary be a key in switching off inflammation” — [r/CIRS](https://www.reddit.com/r/CIRS/comments/17edxt1/thymulin/k8c91zz/)

## Studies

- [Amor et al., Nonathymulin in rheumatoid arthritis: two double blind, placebo controlled trials (Ann Rheum Dis 1987)](https://pubmed.ncbi.nlm.nih.gov/3310925/) (rct, 1987): Six months of daily or thrice-weekly subcutaneous thymulin at 1, 5 or 10 mg/day: 5 mg/day improved global assessment in 56% vs 17% on a zinc-matched placebo, with minimal adverse effects and no clear change in immune markers.
- [Bordigoni et al., Improvement of cellular immunity and IgA production in immunodeficient children after treatment with synthetic serum thymic factor (Lancet 1982)](https://pubmed.ncbi.nlm.nih.gov/6124716/) (observational, n=3, 1982): Three children with T-cell and IgA defects had fewer infections, better cell-mediated immunity and newly appearing IgA on IV FTS; the gains regressed when it was paused and returned on restarting.
- [Vickers, An analysis of the safety and efficacy of topical zinc-thymulin to treat androgenetic alopecia (Hair Ther Transplant 2017)](https://www.longdom.org/abstract/an-analysis-of-the-safety-and-efficacy-of-topical-zincthymulin-to-treat-androgenetic-alopecia-30735.html) (open-label, n=18, 2017): A water-based zinc-thymulin scalp spray for 4-10 months, with blinded photo grading: more vellus (32%) and intermediate (23%) hairs at 6 months and no scalp irritation or systemic effects over 3,300 treatment days. Single author, no control group.
- [Meier et al., Thymic peptides differentially modulate human hair follicle growth (J Invest Dermatol 2012)](https://pubmed.ncbi.nlm.nih.gov/22402437/) (in-vitro, 2012): In organ-cultured human scalp follicles, thymulin increased hair-shaft growth and prolonged anagen, while thymosin beta-4 pushed follicles towards regression.
- [Prasad et al., Serum thymulin in human zinc deficiency (J Clin Invest 1988)](https://pubmed.ncbi.nlm.nih.gov/3262625/) (observational, n=14, 1988): Thymulin activity in blood depends on zinc: it fell in mildly zinc-deficient adults (two induced by diet, twelve with existing deficiency) and recovered with zinc repletion, along with their T-cell subsets and IL-2.
- [Reggiani et al., The thymus-neuroendocrine axis: physiology, molecular biology, and therapeutic potential of thymulin (Ann N Y Acad Sci 2009)](https://doi.org/10.1111/j.1749-6632.2008.03964.x) (review, 2009): Reviews thymulin's role in T-cell differentiation, its anti-inflammatory and analgesic effects in the rat brain, its effects on pituitary hormone release, and gene-therapy work in animals.
- [Safieh-Garabedian et al., Thymulin reverses inflammatory hyperalgesia and modulates proinflammatory cytokines induced by i.c.v. endotoxin (Neuroscience 2003)](https://pubmed.ncbi.nlm.nih.gov/14580936/) (animal, 2003): In rats, thymulin reversed endotoxin-induced pain behaviour and damped brain inflammatory cytokines.

## Sources

- [Superpower peptide guide: Thymulin](https://superpower.com/guides/peptides/thymulin)
- [Amor et al. 1987, nonathymulin in rheumatoid arthritis (PubMed)](https://pubmed.ncbi.nlm.nih.gov/3310925/)
- [Vickers 2017, topical zinc-thymulin for androgenetic alopecia (DOI)](https://doi.org/10.4172/2167-0951.1000147)
- [Pepta Labs thymulin listing: research vials are the metal-free nonapeptide, not the zinc complex](https://peptalabs.com/peptides/thymulin)
- [PepGrades: thymulin 10 mg vial prices (Oct 2026)](https://pepgrades.com/prices/thymulin-10mg)