Searches for "PCT supplements UK" or "what is a PCT supplement" come down to one question: what is actually in the bottle? This guide sorts the usual ingredients by class, with the UK regulatory position, research and sport status of each, and the evidence on hormone recovery after anabolic steroids and on mislabelled products. It contains no guidance on use.
What "PCT" means on a product label
PCT stands for post-cycle therapy, a bodybuilding term for attempts to restart the body's own testosterone production after anabolic steroids or similar compounds have suppressed it. A 2026 review names the agents most commonly involved as selective oestrogen receptor modulators (SERMs), human chorionic gonadotrophin (hCG) and aromatase inhibitors (Smit 2026).
PCT is not a legal or pharmacological category. It is a label used for three different kinds of product:
- Prescription only medicines such as clomifene, tamoxifen and the aromatase inhibitors, licensed for other conditions.
- Research blends sold under a product name for laboratory use, with a composition set by the manufacturer.
- Food supplements built on herbal extracts, amino acids, vitamins and minerals.
PCT blend ingredients at a glance
| Ingredient class | Examples | UK status | WADA 2026 |
|---|---|---|---|
| SERMs | Clomifene, tamoxifen | Prescription only medicines, licensed for infertility in women and, for tamoxifen, breast cancer | Prohibited at all times (S4.2) |
| Single SERM isomer | Enclomiphene | No UK marketing authorisation | Prohibited at all times (S4.2) |
| Aromatase inhibitors | Anastrozole, letrozole, exemestane | Prescription-only medicines, licensed mainly for breast cancer | Prohibited at all times (S4.1) |
| Herbal extracts and amino acids | Tongkat ali, D-aspartic acid, Tribulus terrestris, ashwagandha | Sold as food supplements; no authorised health claim in the GB register | Not named on the list |
| Vitamins and minerals | Zinc, magnesium, vitamin D | Food supplement ingredients; one authorised zinc claim mentions testosterone | Not named on the list |
SERMs: clomifene, tamoxifen and enclomiphene
In men, oestradiol restrains the release of luteinising hormone (LH) and follicle-stimulating hormone (FSH), which drive testosterone and sperm production; this loop is the hypothalamic-pituitary-testicular axis. A SERM blocks oestrogen receptors at the hypothalamus and pituitary, which is why the class features in discussions of hormone recovery. Chemistry and trials are in our enclomiphene vs clomifene guide; here the question is regulation.
Clomifene and tamoxifen: licensed, but not for this
Both are licensed UK medicines, but neither is licensed for men coming off anabolic steroids. The MHRA-approved information for Clomid gives one indication, ovulatory failure in women seeking pregnancy, and its patient leaflet states that it should not be taken by men. Tamoxifen's licence covers breast cancer, anovulatory infertility and breast cancer prevention in women at raised risk. Both are prescription only medicines: tamoxifen's MHRA public assessment report says so, and the electronic medicines compendium lists licensed clomifene tablets in the same category (MHRA; emc).
The same documents record adverse effects. Clomid's summary of product characteristics warns of visual symptoms, from blurring and flashes to partial or complete loss of vision, usually reversible but in some cases prolonged or permanent, including after treatment stopped. Tamoxifen's summary reports a two- to threefold increase in the risk of venous thromboembolism, blood clots in the veins, in healthy women taking it (MHRA).
Enclomiphene: no UK authorisation
Enclomiphene is one of clomifene's two geometric isomers, isolated on its own. It has been tested in randomised, placebo-controlled phase III trials in overweight men with secondary hypogonadism (Kim 2016), but it holds no UK marketing authorisation: a search of the MHRA products database for enclomiphene or enclomifene returns no licensed product (MHRA). The products in our enclomiphene collection are supplied as research chemicals, to adults aged 18 or over, not for human consumption, and trial results in patients are not claims about them.
Aromatase inhibitors: anastrozole, letrozole and exemestane
Aromatase converts androgens such as testosterone into oestrogens. Aromatase inhibitors block it and so lower oestrogen levels. Anastrozole, letrozole and exemestane are licensed in the UK mainly for hormone-dependent breast cancer, and the MHRA public assessment reports for generic versions of each state that the medicine is available only on prescription (MHRA).
Herbal and nutrient ingredients
Supplement-style PCT products may list ingredients that are also sold as "testosterone boosters". A 2024 systematic review covered 52 studies on 27 such ingredients, including vitamin D, zinc and magnesium, Tribulus terrestris, Eurycoma longifolia (tongkat ali), Withania somnifera (ashwagandha) and D-aspartic acid (Morgado 2024).
What the research reports
The review asked whether total testosterone rose compared with placebo, and concluded that most of the ingredients failed to increase it. Its authors rated Eurycoma longifolia, which had three studies, as possibly effective in men with late-onset hypogonadism and in healthy men, and ashwagandha as possibly effective in healthy men. D-aspartic acid, Tribulus terrestris, zinc, magnesium and vitamin D were not among the ingredients rated effective. None of its four study populations was men coming off anabolic steroids, so it says nothing about recovery from suppression.
How they are regulated
Under the Food Supplements (England) Regulations 2003, a food supplement is a food intended to supplement the normal diet, a concentrated source of nutrients or other substances with a nutritional or physiological effect, sold in dose form such as capsules. The Department of Health and Social Care states that only authorised claims in the Great Britain nutrition and health claims register may be used in Great Britain. The register, last updated in May 2026, contains no authorised health claim for Eurycoma longifolia, D-aspartic acid, Tribulus terrestris or ashwagandha. Its only claim that mentions testosterone is for zinc: "Zinc contributes to the maintenance of normal testosterone levels in the blood", usable only on foods that are at least a source of zinc (DHSC). Maintaining normal levels is not the same as restoring them after suppression. Some "on hold" claims may also be used under transitional arrangements, but they are not authorised.
What research reports on recovery after anabolic steroids
A 2026 narrative review concluded that the evidence for PCT is limited, that most data come from observational studies or are extrapolated from other forms of secondary hypogonadism, and that, although some studies suggest PCT may speed short-term recovery, spontaneous recovery occurs in most men within months of stopping. It noted that PCT is generally not recommended from an academic standpoint because of uncertain benefits and potential risks (Smit 2026). We know of no published study of a multi-ingredient PCT blend as a product.
Recovery after stopping: the HAARLEM study
This Dutch prospective observational study followed 100 male amateur athletes who intended to start a self-administered course of anabolic steroids, with blood and semen tests before the course, at its end, three months after it ended and one year after it began (Smit 2021). During use, 77 per cent had a total sperm count below 40 million. Three months after stopping, total and free testosterone no longer differed significantly from baseline, but sperm counts were still significantly lower. At the end of follow-up, nine men (11 per cent) had testosterone below the normal range and 25 (34 per cent) had a sperm count below 40 million. The authors note that follow-up was short compared with the time sperm production takes to recover.
Self-reported PCT: a retrospective clinic study
A UK-led retrospective study analysed 641 men attending a single clinic between 2015 and 2022 who had one blood test within 36 months of stopping anabolic steroids (Grant 2023). Only 48.2 per cent had LH, FSH and total testosterone all in the reference range. Self-reported PCT use was associated with faster biochemical recovery, a median of 13 weeks against 26, but only as a short-term association: in men who had stopped steroids longer ago, PCT use was not associated with recovery. Men who had used several steroids were less likely to have recovered than men who had used one. With one blood test per man, the association cannot show cause and effect. The authors call PCT "illicit, ill-defined, and not recommended" and say the association warrants further investigation.
A blood test, not a label, shows whether the axis has recovered. Anyone worried about their hormones after using anabolic steroids or SARMs should speak to a GP or a specialist harm-reduction service.
Status in sport: WADA section S4
Section S4 of the WADA Prohibited List, hormone and metabolic modulators, is prohibited at all times, in and out of competition. S4.1 covers aromatase inhibitors: anastrozole, letrozole and exemestane, but also steroid-derived compounds such as arimistane and androstatrienedione, so a product can contain a prohibited aromatase inhibitor without containing a licensed medicine. S4.2 covers anti-oestrogenic substances, meaning anti-oestrogens and SERMs, and names clomifene and tamoxifen (WADA 2026). Both lists read "including, but not limited to", so enclomiphene, a SERM that is not named, falls within S4.2. Chorionic gonadotrophin (hCG) is prohibited at all times in men under S2.2.1. The herbal and nutrient ingredients above are not named on the 2026 list, but a blend can only be judged once its contents are verified.
Why label verification matters
Poland's official medicines control laboratory tested 601 samples seized from the illegal performance-drug market by police and prosecutors between January 2020 and August 2024 (Blazewicz 2025). Sixty-three were labelled as PCT drugs: SERMs such as tamoxifen and clomifene, aromatase inhibitors, or hCG and other substances. Of those 63:
- 58.7 per cent contained only the declared active ingredient;
- 6.4 per cent contained the declared ingredient plus an undeclared one;
- 14.3 per cent contained a different, undeclared active ingredient instead;
- 20.6 per cent contained no active ingredient at all.
About one in three did not contain what the label declared. Those were black-market medicines, not research blends or supplements, but the lesson carries over: a label is a claim, and a batch certificate of analysis is the check. For a blend, a useful certificate identifies and quantifies each component, by a stated method such as HPLC or mass spectrometry, and matches the batch number on the pack. A component on the label but not on the certificate was not confirmed. See How to Read a Certificate of Analysis and our UK supplier checklist.
Free Muscle PCT, the blend in our PCT blends collection, is sold under a product name, and there is no clinical literature under that name. Its label and batch certificate, not this article, are the reference for what it contains. Every Free Muscle batch is assayed by Janoshik Analytical, an independent laboratory, and the certificate for a batch is sent by email on request; see our lab tests page. For other brands, such as the Yakka Strength enclomiphene we stock, a certificate is shown only where the manufacturer supplies one for the batch we hold.
Common questions
What is a PCT supplement?
It is a marketing term, not a regulatory category. It usually means a food supplement built on herbal extracts, amino acids or minerals, or a research blend sold under a product name. On forums it can also mean a prescription only medicine such as clomifene. The label shows what the seller claims; a batch certificate of analysis shows what a laboratory found.
Are PCT tablets legal in the UK?
It depends on the ingredient. Clomifene, tamoxifen and the aromatase inhibitors are prescription only medicines. Under the Human Medicines Regulations 2012, a person may not sell or supply a prescription only medicine except in accordance with a prescription given by an appropriate practitioner, such as a doctor. Enclomiphene has no UK marketing authorisation; it and the research blends are sold here only to adults aged 18 or over for laboratory research, not for human consumption. Herbal and nutrient products are sold as food supplements, with health claims restricted by law.
Do PCT supplements work?
We make no claims about what any PCT product does. The 2024 systematic review above found that most ingredients marketed as testosterone boosters did not raise total testosterone against placebo. Research on medicines used after steroids is limited and mostly observational, and a 2026 review concluded that PCT is generally not recommended from an academic standpoint.
What are the side effects of post-cycle therapy?
PCT is not one product, so there is no single answer. The licensed product information above records visual disturbances with clomifene and a raised risk of blood clots with tamoxifen, and about a third of seized PCT drugs in one laboratory study did not contain the declared ingredient. Anyone with symptoms should speak to a doctor.
Does Free Muscle give post-cycle therapy advice?
No. We give no cycle, PCT, timing or dosing advice, and nothing on this site is a protocol. The research compounds sold here, including SARMs, are not licensed medicines and are sold for laboratory research only. Anyone concerned about suppressed testosterone should see a GP or a specialist harm-reduction service, where blood tests for LH, FSH and testosterone show the actual position.
Is a PCT blend the same as enclomiphene?
No. Enclomiphene is a single defined molecule, one isomer of clomifene, with no UK marketing authorisation. A PCT blend is a product name for a mixture with no published literature of its own, and only its batch certificate confirms what it contains. Both are sold here for research only.
Related reading
- PCT blends collection
- Enclomiphene collection
- Enclomiphene vs clomifene: what the trials report
- How to Read a Certificate of Analysis (COA)
- What Is Janoshik Analytical? Third-Party Testing Explained
General information from MHRA, emc, DHSC, legislation.gov.uk and WADA texts checked in September 2026, not legal or medical advice. The research compounds and blends sold by Free Muscle are for laboratory research use only, to customers aged 18 or over. They are not licensed medicines, have not been evaluated by the MHRA, EMA or FDA, are not food supplements and are not for human consumption. Nothing on this page is dosing, cycle or post-cycle guidance, and no product sold here replaces assessment by a doctor. Study summaries describe findings in study populations and are not claims about any product.
References
- Smit DL, et al. Post-cycle therapy after androgen abuse: a narrative review of mechanisms, evidence, and clinical perspectives. Endocr Connect. 2026;15(9):e260319. PMID: 42644333.
- Smit DL, et al. Disruption and recovery of testicular function during and after androgen abuse: the HAARLEM study. Hum Reprod. 2021;36(4):880-890. PMID: 33550376.
- Grant B, et al. Factors predicting normalization of reproductive hormones after cessation of anabolic-androgenic steroids in men: a single center retrospective study. Eur J Endocrinol. 2023;189(6):601-610. PMID: 38102386.
- Morgado A, et al. Do "testosterone boosters" really increase serum total testosterone? A systematic review. Int J Impot Res. 2024;36(4):348-364. PMID: 37697053.
- Kim ED, et al. Oral enclomiphene citrate raises testosterone and preserves sperm counts in obese hypogonadal men, unlike topical testosterone: restoration instead of replacement. BJU Int. 2016;117(4):677-85. PMID: 26496621.
- Blazewicz A, et al. Illegal and falsified medicines self-administrated in not approved post-cycle therapy after the cessation of anabolic-androgenic steroids - qualitative analysis. Front Chem. 2025;13:1536858. PMID: 40177353.
- Medicines and Healthcare products Regulatory Agency. Products database: Clomid 50 mg tablets summary of product characteristics and patient leaflet (PL 56485/0005); Tamoxifen 20 mg tablets summary of product characteristics and public assessment report (PL 16363/0135); public assessment reports for anastrozole 1 mg (PL 18727/0014), letrozole 2.5 mg (PL 18727/0023) and exemestane 25 mg (PL 24668/0260) tablets; searches for enclomiphene and enclomifene. https://products.mhra.gov.uk (accessed 27 September 2026).
- Electronic medicines compendium (emc). Clomifene 50mg Tablets (PL 29831/0037), legal category: prescription only medicine. https://www.medicines.org.uk/emc/product/15080/smpc (accessed 27 September 2026).
- Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register, updated 19 May 2026, and Nutrition and health claims: guidance to compliance with Regulation (EC) 1924/2006, section 1.12. https://www.gov.uk/government/publications/great-britain-nutrition-and-health-claims-nhc-register (accessed 27 September 2026).
- Human Medicines Regulations 2012 (SI 2012/1916), regulation 214; Food Supplements (England) Regulations 2003 (SI 2003/1387), regulation 2. https://www.legislation.gov.uk (accessed 27 September 2026).
- World Anti-Doping Agency. The 2026 Prohibited List, sections S2.2.1, S4.1 and S4.2. https://www.wada-ama.org/en/prohibited-list (accessed 27 September 2026).