We use essential cookies (authentication, your saved goals/stack) by default. With your permission we'll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Prescription medication — not a dietary supplement
Thymopentinis a prescription (or investigational) drug, not a supplement. It is included here for reference because people research and discuss it (often used off-label) — not as a recommendation. Take it only under a qualified clinician's supervision and only as prescribed; do not source it from grey-market vendors, where identity, purity, and dosing are unverified. The evidence below reflects its clinical trials.
What the evidence says
Most Thymopentin studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from mixed-quality meta-analyses and randomised trials published 1985–2022.
Based on 11 studies · 5 meta-analyses · 3 RCTs
Confidence
HighBy outcome
The current evidence for Thymopentin is insufficient to assign an evidence score, based on 11 indexed studies, including 5 meta-analyses. A synthetic pentapeptide (Arg-Lys-Asp-Val-Tyr) reproducing the active site of the thymic hormone thymopoietin. Unlike grey-market peptides, thymopentin was a genuinely registered immunomodulator drug — marketed as Timunox in Italy and widely used in China — so it has real Western randomized trials behind it, not just anecdote. The strongest data are small placebo-controlled RCTs in active rheumatoid arthritis from the 1980s (Lancet, German multicentre) showing short-lived symptomatic improvement, and a 352-patient double-blind HIV trial where it modestly delayed disease progression. But the evidence is old, heterogeneous, and short-duration; benefits faded weeks after stopping; it failed as a vaccine adjuvant in at least one trial; and it is NOT an FDA-approved drug or a dietary supplement. Modern meta-analyses pooling Chinese adjuvant-therapy trials (tuberculosis, lung cancer) report benefits but are dominated by low-quality, unblinded studies. Treat this as a real but weakly-evidenced legacy immunomodulator, not a proven supplement. Representative study: PMID 26252373.
PT-141
Mostly mechanism / observationalA melanocortin-receptor (MC4R) agonist peptide for low sexual desire. Important honest framing: unlike most 'research peptides', bremelanotide is an FDA-APPROVED prescription drug — Vyleesi, approved 2019 — for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women, self-injected subcutaneously on-demand. It has real phase-3 RCTs (the RECONNECT program). The catch: the approved-trial benefit was statistically significant but small (a fraction of a point on desire scales), nausea is very common, and it transiently raises blood pressure. Grey-market 'PT-141' vials sold online are NOT the approved drug and are unregulated.
Last reviewed June 2026 · evidence from 11 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Thymopentin (TP-5, thymopoietin 32-36)
A synthetic pentapeptide (Arg-Lys-Asp-Val-Tyr) reproducing the active site of the thymic hormone thymopoietin. Unlike grey-market peptides, thymopentin was a genuinely registered immunomodulator drug — marketed as Timunox in Italy and widely used in China — so it has real Western randomized trials behind it, not just anecdote. The strongest data are small placebo-controlled RCTs in active rheumatoid arthritis from the 1980s (Lancet, German multicentre) showing short-lived symptomatic improvement, and a 352-patient double-blind HIV trial where it modestly delayed disease progression. But the evidence is old, heterogeneous, and short-duration; benefits faded weeks after stopping; it failed as a vaccine adjuvant in at least one trial; and it is NOT an FDA-approved drug or a dietary supplement. Modern meta-analyses pooling Chinese adjuvant-therapy trials (tuberculosis, lung cancer) report benefits but are dominated by low-quality, unblinded studies. Treat this as a real but weakly-evidenced legacy immunomodulator, not a proven supplement.
A legacy immunomodulator drug with genuine Western placebo-controlled RCTs, but benefits were modest, transient and dated, and modern positive meta-analyses rest on low-quality unblinded trials.
Thymopentin (TP-5) is a synthetic pentapeptide with the sequence Arg-Lys-Asp-Val-Tyr, corresponding to residues 32-36 of thymopoietin, a polypeptide hormone produced by thymic epithelium.
The fragment reproduces the immunoregulatory ('biological') activity of the full hormone: it promotes T-lymphocyte differentiation and is reported to normalize T-cell subset ratios (CD4/CD8), nudging a dysregulated immune system back toward balance rather than simply stimulating it.
Because of this, thymopentin was developed as a pharmaceutical immunomodulator and was marketed under the brand Timunox (notably in Italy), with extensive subsequent use in China as an adjuvant in infectious disease and oncology.
That regulatory history matters: it means thymopentin has a body of real, PubMed-indexed human trials — including Western placebo-controlled RCTs — which is genuinely unusual for the peptides in this category.
The best-quality evidence comes from active rheumatoid arthritis: a 1985 Lancet double-blind placebo-controlled study (41 patients, slow IV TP-5 50 mg three times weekly for three weeks) found significant improvement over placebo in joint tenderness, swelling, pain and disease activity, with only minor side-effects — but the improvement faded over the four weeks after treatment stopped, and there were no changes in any laboratory or immunological markers.
A larger German multicentre placebo-controlled RCT (119 patients) reproduced the short-term symptomatic benefit.
In HIV, a 352-patient double-blind placebo-controlled trial in zidovudine-experienced asymptomatic patients reported that thymopentin delayed progression to ARC/AIDS/death, an effect magnified in higher-risk subgroups — a legitimate but historical signal from the pre-HAART era.
Modern systematic reviews and meta-analyses exist but must be read carefully: a 2022 meta-analysis of thymopentin as an adjuvant in drug-resistant pulmonary tuberculosis (23 RCTs, 2031 patients) reported higher sputum-conversion and focal-absorption rates and improved CD4 counts, and broader meta-analyses of synthetic thymic peptides in non-small-cell lung cancer report response-rate and quality-of-life gains — but these pools are dominated by small, unblinded, single-country (largely Chinese) trials of unclear-to-very-low quality, and the lung-cancer meta-analysis is driven mostly by thymosin-alpha-1 rather than thymopentin specifically.
The honest counterweights are equally real: a meta-analysis of 11 trials found thymopentin did not overall improve the hepatitis-B-vaccine seroresponse in dialysis patients (only a higher-dose subgroup did); thymopentin failed as an influenza-vaccine immunoadjuvant in elderly patients in one controlled study; the Cochrane review of thymic peptides in cancer found no survival or tumour-response benefit; and the Cochrane review of cold-sore prevention found only 'very few data' suggesting benefit.
The honest framing therefore is: thymopentin is a real approved/marketed immunomodulator drug outside the United States with genuine (if dated and heterogeneous) trial evidence, but its effects are typically modest, short-lived, and supported largely by old or low-quality studies; Western regulators have NOT approved it; long-term safety beyond the studied weeks-to-months is poorly characterized; and it is neither an FDA-approved medicine nor a lawful dietary supplement.
It should be used only under a clinician in jurisdictions where it is a registered drug.
Thymopentin reproduces the active site (residues 32-36) of the thymic hormone thymopoietin. It promotes maturation of T lymphocytes and is reported to normalize T-cell subset balance — shifting dysregulated CD4/CD8 ratios back toward normal in conditions such as rheumatoid arthritis, multiple sclerosis and HIV, rather than acting as a blunt immune stimulant.
Across trials, thymopentin is framed as an immunoregulator: in autoimmune synovitis it increased suppressor/naive T-cell populations, while in immunodeficiency states it supported CD4 counts. The proposed action is restoring immune homeostasis — but the molecular target downstream of the peptide is not fully characterized in humans.
How Thymopentin works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Tap node to isolate • Pinch to zoom • Tap edge for research
Thymopentin is a prescription/registered immunomodulator drug outside the US, NOT a dietary supplement — this library does not provide a self-administration protocol. For reference only, the dose used in the active-RA RCTs was 50 mg given by slow intravenous injection three times weekly for three weeks; other regimens used subcutaneous dosing. Any use must be directed by a clinician in a jurisdiction where it is a registered drug.
Can be taken without food
| Form | Type |
|---|---|
| 🧪Lyophilized powder for injection (registered drug where approved) | Recommended |
Thymopentin is administered by injection. There is no oral supplement form; oral peptide would be digested.
Minimum: 3 weeks
Optimal: 3 weeks
Cycling: Not required
Note: Injectable prescription drug — timing follows the clinical dosing schedule, not supplement-style 'with food' or time-of-day rules.
Dose-response data unavailable. The current published research for Thymopentin does not provide sufficient dose-specific outcome data to generate reliable dose-response curves.
Refer to the Dosage & Timing section above for recommended dose ranges based on available evidence.
Thymopentin has real human trials, including a few Western placebo-controlled RCTs — but the best of these are small (≈40-120 patients), short (≈3 weeks of dosing), from the 1980s-90s, and showed benefits that faded after stopping. Modern positive meta-analyses are dominated by small, unblinded, single-country adjuvant-therapy trials of low-to-very-low quality. It is approved/marketed abroad but not FDA-approved.
In small placebo-controlled RCTs, IV thymopentin significantly reduced joint tenderness, swelling, morning pain and disease activity in active RA over 3 weeks — but the improvement gradually subsided within ~4 weeks of stopping and no laboratory markers changed.
In a 352-patient double-blind trial of zidovudine-experienced asymptomatic patients, thymopentin delayed progression to ARC/AIDS/death, with the effect strongest in higher-risk subgroups. A legitimate but historical, pre-modern-therapy signal.
Meta-analyses of thymopentin (or synthetic thymic peptides) added to chemotherapy/anti-TB drugs report improved response rates, CD4 counts and quality of life — but these pools are dominated by small, unblinded Chinese RCTs of low-to-very-low quality.
A meta-analysis of 11 trials in dialysis patients found thymopentin did NOT overall improve the hepatitis-B-vaccine seroresponse (only a higher-dose subgroup did), and it did NOT improve influenza-vaccine antibody response in elderly people in a controlled study; the Cochrane cold-sore review found only very sparse evidence — an honest reminder that the benefits are inconsistent.
Trials dosed for weeks to months and reported mostly minor side-effects (occasional allergic reactions). Effects of prolonged or repeated courses, and modern long-term safety, are not well studied.
Avoid — safety in pregnancy and lactation is not established.
Only under specialist supervision — thymopentin modulates T-cell balance and its net effect in a given autoimmune condition is unpredictable.
Avoid unregulated sources — identity, purity and sterility are not guaranteed; a registered pharmaceutical product (where it exists) under clinical care is the only defensible route.
As an immunoregulatory agent, thymopentin could theoretically counteract or compound the effects of immunosuppressants or other immunomodulators. Combined use has not been systematically studied and should be clinician-supervised.
Thymopentin has been trialed as a vaccine adjuvant with inconsistent (including negative) results; it should not be assumed to improve vaccine response and any combined use should be clinician-directed.
Tip: Trials reported mostly minor side-effects from IV/SC dosing; administer per clinical protocol.
Tip: At least one RA RCT recorded a systemic allergic reaction; stop and seek care if hypersensitivity occurs.
Tip: Long-term and repeated-course safety is not well characterized; do not self-administer chronically.
The commonly studied dose of Thymopentin is Thymopentin is a prescription/registered immunomodulator drug outside the US, NOT a dietary supplement — this library does not provide a self-administration protocol. For reference only, the dose used in the active-RA RCTs was 50 mg given by slow intravenous injection three times weekly for three weeks; other regimens used subcutaneous dosing. Any use must be directed by a clinician in a jurisdiction where it is a registered drug.. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Timing is flexible for Thymopentin — consistent daily use matters more than the time of day. Thymopentin is injected (IV or subcutaneous) and its timing in trials was driven by the dosing schedule, not by food or circadian factors.
Thymopentin should be used with caution — talk to a healthcare provider before taking it. The most commonly reported side effects are injection-related reactions, systemic allergic / hypersensitivity reaction, unknown long-term effects. Use caution if any of these apply to you: Not an FDA-approved drug or a regulated dietary supplement — approved/marketed as a prescription immunomodulator only in some countries; use only under a clinician; Known hypersensitivity to thymopentin (systemic allergic reactions have been reported); Pregnancy and breastfeeding (not established as safe).
Gonadorelin
Mostly mechanism / observationalA synthetic copy of gonadotropin-releasing hormone (GnRH), the hypothalamic decapeptide that drives the pituitary to release LH and FSH. Honest appraisal: it has genuine, trial-backed roles as a diagnostic agent (the GnRH/gonadorelin stimulation test) and — delivered in pulses by an infusion pump — for inducing ovulation in hypothalamic amenorrhea and spermatogenesis in men with congenital hypogonadotropic hypogonadism. Its now-trendy use in men's TRT clinics (compounded, to 'maintain testosterone/fertility' alongside testosterone, often replacing hCG) is largely off-label and has NOT been validated in controlled trials for that purpose.