Is the breast cancer drug tamoxifen being sold as a bodybuilding dietary supplement?

5 February 2014

As Elsharkawy et al., note many anabolic steroid users take more than one steroid at a time in the belief that they will have additional and/or synergistic effects. [1] Many also use drugs to prevent and treat side effects arising from steroid use. [2] One drug that is commonly used in this respect is the anti-oestrogen tamoxifen which steroid users have used for more than 30 years to prevent and treat gynaecomastia. [2,3] This unwanted side effect is caused by an imbalance between androgens and oestrogens. [4] Usually, tamoxifen is sourced from the illicit market. [5] However, discussions on Internet bodybuilding forums have speculated that a product called “Esto Suppress” marketed as a “dietary supplement” contains tamoxifen as the label listed one of its chemical names: (Z)-1-(p-dimethylaminoethoxyphenyl)-1,2-diphenyl-1-butene (Figure). In order to investigate this, four samples of the product were purchased from a fitness equipment shop in Merseyside at different time points over a period of more than six months in late 2011 and early 2012. The content of the products were analysed using reference standards and gas chromatography techniques coupled with flame ionisation and mass spectrometry detectors.

Tamoxifen was identified in samples 1 (3.8 mg), 2 (0.9 mg) and 3 (3.0 mg) but was not detected in sample 4 (the final sample that was purchased). The product label suggested a dosage regimen of two capsules per day, which in the case of samples 1 and 3 may have provided a daily dose of 7.6 mg and 6 mg respectively. In comparison, 10–20 mg are used clinically for treating gynaecomastia. [6] It is not known whether the “Esto Suppress” product currently being sold contains tamoxifen.

Since the 2000s, a growing number of off-the-shelf products sold as “food”, “herbal” or “dietary supplements” aimed at the lifestyle market—such as gym goers, people looking to lose weight, or enhance their sex lives—have been found to contain pharmacologically active substances. [2] These include: anabolic steroids, growth hormones, aromatase inhibitors, erectogenics, stimulants, appetite suppressants, anxiolytics, diuretics and laxatives. [2,7] Some of these substances have been withdrawn from use in medicines due to safety concerns (e.g. the anorectic rimonabant) or they have never been tested in humans (e.g. the anabolic steroid methasterone). In many cases the substances are not listed on the labelling, and products may be marketed as “natural” exploiting the belief that such products are safer and healthier alternatives to synthetic substances. [8] In other cases, such as with “Esto Suppress”, only an obscure reference is made to the substance—such as a chemical name, which sometimes may be misspelled which is likely to have the effect of hiding the true ingredients from both consumers and regulators. Most users are likely to be unaware that they are taking these substances. Healthcare professionals should be aware of these developments, and, where relevant, ask their patients about any kind of “supplements” that they may use. In the UK, suspected adverse drug reactions should be reported through the yellow card scheme (

Figure. “Esto Suppress” that contained tamoxifen. The label of the product lists tamoxifen only by the chemical name (Z)-1-(p-dimethylaminoethoxyphenyl)-1,2-diphenyl-1-butene. The systematic name for tamoxifen is: (Z)-2-(4-(1,2-diphenylbut-1-en-1-yl)phenoxy)-N,N-dimethylethan-1-amine.


1. Elsharkawy AM, McPherson S, Masson S, Burt AD, Dawson RT, Hudson M. Cholestasis secondary to anabolic steroid use in young men. BMJ. 2012;344:e468.

2. Evans-Brown M, McVeigh J, Perkins C, et al. Human enhancement drugs. The emerging challenges to public health. Liverpool, North West Public Health Observatory, 2012.

3. Spano F, Ryan WG. Tamoxifen for gynecomastia induced by anabolic steroids? N Engl J Med 1984;311:861–2.

4. Nieschlag E, Behre HM, Nieschlag S, eds. Testosterone: action, deficiency, substitution. 4th edn. Cambridge, Cambridge University Press, 2012. 

5. Thevis M, Schrader Y, Thomas A, et al. Analysis of confiscated black market drugs using chromatographic and mass spectrometric approaches. J Anal Toxicol 2008;32:232–40.

6. Kunath F, Keck B, Antes G, Wullich B, Meerpohl JJ. Tamoxifen for the management of breast events induced by non-steroidal antiandrogens in patients with prostate cancer: a systematic review. BMC Med 2012;10:96.

7. Food and Drug Administration. Tainted_Supplements_CDER.

8. Ipsos MORI. Public perceptions of herbal medicine. General public qualitative & quantitative research. Ipsos MORI 2008.


Michael Evans-Brown (a*), Andreas Kimergård (b), Jim McVeigh (c), Martin Chandler (d), Simon D. Brandt (e)

(a) scientific analyst, European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), Lisbon, Portugal

(b) visiting lecturer, Centre for Public Health, Liverpool John Moores University, 15–21 Webster Street, Liverpool, L3 2ET, United Kingdom

(c) deputy director, Centre for Public Health, Liverpool John Moores University, 15–21 Webster Street, Liverpool, L3 2ET, United Kingdom

(d) human enhancement drugs researcher, Centre for Public Health, Liverpool John Moores University, 15–21 Webster Street, Liverpool, L3 2ET, United Kingdom

(e) reader in bioactive drug chemistry, School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, L3 3AF, United Kingdom

*Correspondance to Michael.Evans-Brown[AT]

Competing interests: None declared

Michael Evans-Brown, Scientific Analyst

Andreas Kimergård, Jim McVeigh, Martin Chandler, Simon D. Brandt

European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), Lisbon, Portugal

Click to like: