Ask the Doctor: Are Covid Vaccines Risky for Men Receiving Hormone Injections?

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Question for Dr. Rona:

If a man in his early to mid 60’s takes a testosterone shot once a month, is it dangerous to take the Covid shot and booster shots as well?  I have tried to find out but get conflicting answers from different sources. Thank you so much, Louise D.

Dear Louise:

The issue of an interaction between the Covid-19 vaccines and testosterone injections has not been fully studied. What is known, however, is that testosterone injections can cause polycythemia (high red cell counts) in about 20% of men receiving the hormone injections. This increases the risk of abnormal or excessive blood clotting leading to strokes, heart attacks, deep vein thrombosis and possible pulmonary embolus. This occurs because testosterone can stimulate the production of erythropoietin (EPO), a hormone made by the kidneys that stimulates the production of red blood cells.

Both Covid-19 infections as well as the Covid-19 vaccines have been reported to cause elevations in the protein known as fibrin-D-dimer which increases the likelihood of the same abnormal clotting phenomenon. This has been reported to be rare.

Theoretically then, testosterone shots, Covid-19 infections, and the Covid-19 vaccines could be associated with an increased blood clotting risk. Although there is no evidence of a direct interaction between testosterone and the vaccines, the risk of abnormal blood clotting phenomena – rare as that might be – is there.

Periodic testing of the complete blood count (CBC) and testosterone levels could be done to rule out the polycythemia side effect and the dose of the injections modified based on the lab results. Similarly, abnormal blood clotting can be determined by laboratory testing if symptoms such as leg pain and breathing difficulties occur. Hopefully this answers your question.


Zoltan P. Rona, M.D., M.Sc.


Zoltan P. Rona, MD, MSc, offers consultations on nutrition and natural remedies in Thornhill. He has recently retired from medical practice as a Complementary and Alternative medical practitioner and now strictly offers nutritional consultations. He is the medical editor of The Encyclopedia of Natural Healing and has also published several Canadian bestselling books, including Vitamin D, The Sunshine Vitamin. To see more of Dr. Rona’s articles, visit: and for appointments, please call (905) 764-8700; office located at: 390 Steeles Ave. W., Unit 19, Thornhill, Ontario

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