Letters Bodybuilding supplements

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

BMJ 2014; 348 doi: http://dx.doi.org/10.1136/bmj.g1476 (Published 13 February 2014) Cite this as: BMJ 2014;348:g1476
  1. Michael Evans-Brown, scientific analyst1,
  2. Andreas Kimergård, visiting lecturer2,
  3. Jim McVeigh, deputy director2,
  4. Martin Chandler, human enhancement drugs researcher2,
  5. Simon D Brandt, reader in bioactive drug chemistry3
  1. 1European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), Lisbon, Portugal
  2. 2Centre for Public Health, Liverpool John Moores University, Liverpool, UK
  3. 3School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK
  1. Michael.Evans-Brown{at}emcdda.europa.eu

For more than 30 years, bodybuilders have taken tamoxifen to prevent and treat gynaecomastia caused by use of anabolic steroids.1 2 3 Usually, tamoxifen is sourced from the illicit market. However, bodybuilding discussion forums have speculated that a dietary supplement called Esto Suppress contains tamoxifen because the label listed one of its chemical names (figure). Four samples were purchased at different times between late 2011 and early 2012 and were analysed using reference standards and gas chromatography coupled with flame ionisation and mass spectrometry detectors. Tamoxifen was found in samples 1 (3.8 mg), 2 (0.9 mg), and 3 (3.0 mg), but not in sample 4. The product label suggested a dosage of two capsules a day, which in the case of sample 1 may have provided 7.6 mg of tamoxifen; 10-20 mg is used clinically for treating gynaecomastia.4 It is not known whether the Esto Suppress currently being sold still contains tamoxifen.


Esto Suppress containing tamoxifen. The label lists tamoxifen only by 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

Since the 2000s, a growing number of off-the-shelf “food,” “herbal,” or “dietary” “supplements”—aimed at gym goers and people wanting to lose weight or enhance their sex lives—have contained pharmacologically active substances.3 These include anabolic steroids, erectogenics, stimulants, appetite suppressants, and anxiolytics.3 5 Some of these substances have been withdrawn from use in medicines owing to safety concerns, others have never been tested in humans. Often the substances are not listed on the labelling, and products may be marketed as “natural,” exploiting the belief that they are safer and healthier options.6 In other cases, such as with Esto Suppress, only an obscure reference is made to the substance, such as a chemical name. Most users will be unaware that they are taking these substances. Healthcare professionals should ask their patients about their use of “supplements” and report suspected adverse reactions (in the UK: https://yellowcard.mhra.gov.uk).


Cite this as: BMJ 2014;348:g1476