Education Blog for Healthcare Professionals

Testosterone and Thrombosis

Testosterone Replacement Therapy

Replacement therapy with low doses of testosterone does not adversely affect blood coagulation status [ref 1] and does not appear to increase the risk of venous or arterial thrombosis. Thrombosis is not listed as a potential side effect in the commly used drug compendium (Micromedex). Furthermore, the 2006 “Clinical Practice Guideline” from the Endocrine Society also does not list thrombosis as a side effect of testosterone replacement therapy, or a previous history of blood clots as a reason not to give testosterone replacement therapy [ref 2]. However, the Androgel® package insert (prescribing information) lists “blood clots in the legs” as a potential side effect [ref 3], because one patient out of 163 patients on Androgel® developed a DVT over a 3 year period of time (details here). However, whether the DVT was caused by Androgel® or conicidental, is not known.

Anabolic Steroid Use/Abuse

Anabolic steroids are chemical variants of testosterone. They are taken in various doses, typically by athletes, to enhance muscle mass and physical performance. Several cardiovascular complications have been reported to occur in people using anabolic steroids, including high blood pressure, stroke, myocardial infarction, and pulmonary embolism [ref 4]. It is impossible to get a real sense of how frequent these complications occur, as it is difficult to find athletes for cardiovascular investigations who admit that they have taken anabolic steroids. Anabolic steroids taken long-term may increase the risk for arteriosclerosis due to a change in the metabolism of blood lipids: LDL increases and HDL decreases [ref 5]. Anabolic steroids may also lead to increased thrombus formation, even when taken only short-term, because they (a) increase levels of clotting factors (= pro-coagulant factors), (b) decrease levels of fibrinolytic proteins, and (c) lead to increased platelet aggregation [ref 6].


Patient Examples – Explanations

Patient #1: “A 54 years old man had an unexplained leg DVT 4 years ago. He was treated with warfarin for 6 months and has done fine since then. Because of a decrease in libido he was recently tested and found to have a low serum testosterone level. Is it safe for him to take testosterone or does it increase his risk for another blood clot?”

Answer #1:   Physiological testosterone replacement therapy does not appear to increase the risk for blood clots and appears to be safe to take. A history of DVT is also not listed in the 2006 “Clinical Practice Guideline” of the Endocrine Society as a reason to not give testosterone therapy.

Patient #2: A male patient has had one trauma-related DVT in the past and is no longer on warfarin. He has recently been diagnosed with low serum levels of testosterone, found following the discovery of a spinal compression fracture/ osteopenia. Does testosterone replacement therapy  increase his risk for recurrent DVT?

Answer #2: see answer #1.



  1. Smith AM et al. Testosterone does not adversely affect fibrinogen or tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) levels in 46 men with chronic stable angina. Eur J Endocrinol 2005 Feb;152(2):285-91.
  2. Bhasin S et al. Testosterone therapy in adult men with androgen deficiency syndromes: an endocrine society clinical practice guideline. J Clin Endocrinol Metab.2006 Jun;91(6):1995-2010. Erratum in: J Clin Endocrinol Metab 2006 Jul;91(7):2688.
  3. Last accessed March 15th, 2011.
  4. Vanberg, P et al. Androgenic anabolic steroid abuse and the cardiovascular system. Handb Exp Pharmacol. 2010;(195):411-57.
  5. Glazer G. Atherogenic effects of anabolic steroids on serum lipid levels. Arch Intern Med 1991;151:1925-33.
  6. Ferenchick GS. Anabolic-androgenic steroids and thrombosis: is there a connection? Med Hypothesis 1991; 35:27-31.


For Patients: This same education blog, written for patients and non-health care professionals, can be found here.

Disclosure: I have no financial disclosure relevant to this blog entry.

Last updated: March 18th, 2011

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