Testosterone replacement therapy has a short list of firm contraindications and a longer list of conditions that require careful monitoring before and during treatment. The clearest prohibitions, agreed on across major international guidelines, include untreated prostate or breast cancer, a desire to conceive in the near future, pregnancy or possible pregnancy, and severely elevated red blood cell counts. Beyond those, several other health conditions don’t necessarily rule out therapy but do change the risk-benefit calculation enough that a prescriber needs to weigh them seriously.
Cancer-Related Contraindications
Untreated prostate cancer and male breast cancer are listed as absolute contraindications to testosterone therapy across every major guideline, including those from the American Urological Association, the Endocrine Society, and the European Association of Urology.1PubMed Central. Risks of testosterone replacement therapy in men The logic behind this is straightforward: both cancers can be hormone-sensitive, meaning testosterone could fuel tumor growth.
The prostate cancer picture has become more nuanced over the past two decades, though. Early thinking held that higher testosterone levels directly drove prostate cancer risk, but more recent data paints a more complex relationship. Studies examining both baseline testosterone levels and testosterone therapy in relation to new prostate cancer diagnoses have not consistently shown the simple linear link that was once assumed.2Europe PMC. Testosterone Replacement Therapy and Prostate Cancer Incidence Some researchers have even begun cautiously investigating testosterone supplementation in men with a history of treated prostate cancer, though this remains experimental and outside routine clinical practice. The TRAVERSE trial, the largest randomized study of testosterone therapy to date, found no increase in prostate-related events, including prostate cancer, over its follow-up period.3PubMed Central. Long Term Cardiovascular Safety of Testosterone Therapy: A Review of the TRAVERSE Study
Still, an active, untreated prostate or breast cancer remains a hard stop. If you’ve been treated for prostate cancer and your oncologist considers you in remission, a conversation about testosterone therapy is at least possible, but it requires close collaboration between your urologist and endocrinologist and is handled on a case-by-case basis.
Fertility and Testosterone as a Contraceptive
This is one of the most commonly misunderstood aspects of testosterone therapy, and it trips up men and prescribers alike. Exogenous testosterone suppresses the brain’s signals that drive sperm production. Specifically, it shuts down the release of two key hormones from the pituitary gland that the testes need to make sperm.4PubMed Central. Testosterone Is a Contraceptive and Should Not Be Used in Men Who Desire Fertility The result is that sperm counts can drop dramatically, sometimes to zero, while a man is on therapy.
This means testosterone therapy is effectively contraindicated in men who want to father children in the near or medium term. It has actually been studied as a male contraceptive in clinical trials. Fertility usually recovers after stopping treatment, with baseline testosterone and sperm production returning over time, but recovery is not always complete, and the timeline varies from months to over a year.5PubMed Central. Exogenous testosterone: a preventable cause of male infertility For men who have low testosterone and also want to preserve fertility, alternative treatments exist that can raise testosterone levels without suppressing sperm production. If your doctor prescribes testosterone without asking about your family-planning goals, that’s a red flag.
Elevated Red Blood Cell Counts
Testosterone stimulates the bone marrow to produce more red blood cells. For men with anemia, that can actually be a useful side effect. But for anyone who already has a high red blood cell count, adding testosterone on top can push levels into dangerous territory, thickening the blood and raising the risk of stroke and blood clots. This condition, called erythrocytosis or secondary polycythemia, is one of the most common adverse effects of testosterone replacement.6PubMed Central. Testosterone use causing erythrocytosis
Most guidelines recommend checking hematocrit (the percentage of blood volume occupied by red blood cells) before starting therapy and periodically afterward. Several endocrine organizations recommend against starting testosterone in patients who already present with elevated hematocrit, and they advise stopping or adjusting therapy if levels climb too high during treatment.7PubMed Central. Testosterone therapy-induced erythrocytosis: can phlebotomy be justified? When hematocrit does rise, clinicians sometimes recommend blood donation or therapeutic phlebotomy (essentially drawing blood to thin it out), though evidence that phlebotomy is reliably effective or safe in this context is actually limited. Dose reduction or switching to a different testosterone formulation that produces more stable blood levels is often tried first.
Cardiovascular Disease
For years, the cardiovascular safety of testosterone was the biggest open question in the field. An FDA safety communication in 2015 required labels on testosterone products to warn about potential heart attack and stroke risk, and this created widespread caution among both doctors and patients. The uncertainty has largely been resolved by the TRAVERSE trial, which enrolled over 5,200 men aged 45 to 80 who either already had cardiovascular disease or were at high risk of it, and who had confirmed low testosterone. The trial found that testosterone therapy was noninferior to placebo for major cardiovascular events: roughly 7% of men in both the testosterone and placebo groups experienced a primary cardiac endpoint, with no meaningful difference between them.8PubMed. Cardiovascular Safety of Testosterone-Replacement Therapy
This doesn’t mean cardiovascular disease is irrelevant when considering testosterone. Men with a recent heart attack or stroke, or with uncontrolled heart failure, are still treated cautiously in clinical practice. But the blanket fear that testosterone therapy would reliably cause heart attacks has not held up under rigorous testing. Interestingly, a small body of research on testosterone in men with heart failure has found that it can improve exercise capacity, with meaningful increases in walking distance and oxygen consumption compared to placebo, and without significant cardiovascular adverse events.9AHA Journals (Circulation: Heart Failure). Testosterone supplementation in heart failure: a meta-analysis That said, those studies were small, and heart failure patients should only receive testosterone under specialist supervision.
Severe Untreated Sleep Apnea
Obstructive sleep apnea and low testosterone often occur in the same person, partly because obesity drives both conditions. Testosterone therapy should probably be avoided in patients with severe untreated obstructive sleep apnea.10PubMed Central. Obstructive Sleep Apnea and Testosterone Deficiency The concern is that testosterone can worsen airway obstruction during sleep, though the mechanism is not fully understood. It may involve changes to upper-airway muscle tone or fluid distribution in the neck.
The important word here is “untreated.” If you have sleep apnea and are using a CPAP machine or another effective therapy, most clinicians won’t consider it a contraindication to testosterone. The problem arises when someone starts testosterone without knowing they have sleep apnea, or knowing and refusing treatment. If you snore heavily, wake up feeling unrefreshed, or have a partner who has noticed you stop breathing during sleep, it’s worth getting a sleep study before starting testosterone therapy.
Pregnancy and Secondary Exposure
Testosterone is a known teratogen, meaning it can cause birth defects, specifically virilization of a female fetus. Current guidelines recommend that patients discontinue testosterone before attempting pregnancy, though the precise washout period needed to minimize fetal risk is not well established.11PubMed Central. Pregnancy in transgender men This applies to transgender men who may become pregnant and to cisgender women who are using testosterone for any purpose. Pregnancy, confirmed or suspected, is an absolute contraindication.
A related concern is secondary exposure. Topical testosterone gels, one of the most popular delivery methods, can transfer testosterone to other people through skin-to-skin contact. Children and pregnant women are particularly vulnerable. If you use a testosterone gel, covering the application site and washing your hands thoroughly before touching others is not optional, it’s a safety requirement. Cases of accidental virilization in children exposed to a family member’s testosterone gel have been reported, and the FDA added a black-box warning to topical products about this risk.
Liver Considerations and Formulation Differences
The liver toxicity story around testosterone is largely a historical artifact of one specific formulation. Older oral testosterone preparations, particularly the 17-alpha-alkylated versions used decades ago and still associated with anabolic steroid abuse, were genuinely toxic to the liver and could cause a range of problems from elevated liver enzymes to rare but serious conditions like liver tumors. This gave oral testosterone a bad reputation.
Modern oral testosterone formulations have been redesigned to avoid the liver. Newer oral testosterone undecanoate products use a self-emulsifying delivery system that routes absorption through the lymphatic system, bypassing the liver’s first-pass metabolism.12PubMed Central. Testosterone Replacement Therapy: A Narrative Review with a Focus on New Oral Formulations Clinical trials of these newer formulations have found that elevated liver function test values are not generally associated with them, and no clinically significant liver toxicities were observed.13PubMed. Newer formulations of oral testosterone undecanoate: development and liver side effects That said, if you have active liver disease or liver failure, any medication needs careful consideration, and your prescriber will likely choose an injectable or transdermal formulation to minimize hepatic stress entirely.
Urinary Symptoms and the Prostate
Men with severely bothersome lower urinary tract symptoms, such as frequent nighttime urination, weak stream, or a feeling of incomplete bladder emptying, are sometimes cautioned against testosterone. The concern is that testosterone could stimulate prostate growth and worsen these symptoms, or in extreme cases, contribute to urinary retention. Product labels for testosterone still carry warnings about the risk of urinary retention and worsening urinary symptoms.14PubMed Central. Testosterone and benign prostatic hyperplasia
In practice, the evidence here is mixed. Many men with benign prostate enlargement use testosterone without any worsening of their urinary symptoms, and some studies suggest that the relationship between testosterone levels and prostate growth is not as straightforward as once thought. Still, if you already have significant urinary obstruction, starting testosterone without first addressing the prostate issue is asking for trouble. A baseline prostate evaluation and potentially a urology consultation are reasonable steps before beginning therapy.
Blood Clots and Venous Thromboembolism
The question of whether testosterone therapy raises the risk of blood clots, particularly deep vein thrombosis and pulmonary embolism, has been debated extensively. A meta-analysis that pooled results from randomized trials, cohort studies, and case-control studies found no statistically significant association between testosterone therapy and venous thromboembolism, though the overall estimate trended slightly upward and the results were highly variable across different study designs.15Thrombosis Research. Testosterone therapy and venous thromboembolism: A systematic review and meta-analysis In other words, if there is an increased risk, it’s not large or consistent enough to show up reliably across studies.
Most guidelines still list a recent history of venous thromboembolism or a known clotting disorder as at least a relative contraindication, meaning it warrants extra caution rather than an outright ban. If you’ve had a blood clot before or you carry a genetic tendency toward clotting, your doctor will want to weigh that into the decision. Interestingly, a study of men with opioid-induced low testosterone found that testosterone therapy actually shifted several coagulation markers in an anticoagulant direction, reducing clotting potential rather than increasing it.16PubMed Central. Testosterone therapy increases the anticoagulant potential in men with opioid-induced hypogonadism: a randomized, placebo-controlled study The relationship between testosterone and clotting is evidently not as simple as “more testosterone, more clots.”
Psychiatric and Behavioral Effects
One concern that comes up regularly, both in clinical settings and in popular culture, is whether testosterone therapy makes people aggressive or emotionally unstable. The evidence here is actually reassuring for men receiving replacement-dose therapy for diagnosed hypogonadism. A systematic review of clinical evidence found that among young men with normal testosterone levels who received supraphysiological doses (well above what a doctor would prescribe for deficiency), there was a modest increase in self-reported aggression, but no significant effect on overall mood.17Cureus. Psychiatric and Cognitive Effects of Testosterone Therapy in Adult Men: A Systematic Review of Clinical Evidence and Mechanistic Insights The key distinction is between replacement doses that bring a deficient man back to normal range and supraphysiological doses that push levels far above normal. The “roid rage” stereotype comes primarily from the latter scenario, which involves doses many times higher than what legitimate medical treatment uses.
That said, if you have an active, untreated psychiatric condition involving impulsivity or aggression, a clinician will want to stabilize that before adding testosterone to the mix. This is less about testosterone causing psychiatric illness and more about good clinical practice: avoid introducing variables while another condition is in flux.
How Guidelines Differ Across Organizations
One of the frustrating realities of testosterone therapy is that different medical organizations draw slightly different lines. A comparison of guidelines from the American Urological Association, European Association of Urology, American Association of Clinical Endocrinologists, British Society for Sexual Medicine, Endocrine Society, and International Society for Sexual Medicine reveals broad agreement on the absolute contraindications (active prostate or breast cancer, desire for fertility, pregnancy) but varying levels of caution on the relative ones.18PubMed. Guideline of guidelines: testosterone therapy for testosterone deficiency Some societies are stricter about elevated hematocrit thresholds, while others take a more permissive stance on cardiovascular risk. The required monitoring intervals, the recommended blood tests, and the preferred treatment durations all vary.
What this means for you in practice is that the answer to “can I take testosterone” may differ depending on which specialist you see and which guidelines they follow. If one doctor turns you down based on a relative contraindication and you feel the decision wasn’t well explained, seeking a second opinion from someone who specializes in male hormone health is reasonable.
Testosterone in Women and Gender-Affirming Care
Most contraindication discussions center on cisgender men, but testosterone is also prescribed to cisgender women for conditions like low sexual desire and to transgender men as part of gender-affirming hormone therapy. For cisgender women, testosterone is used at much lower doses, and the contraindication profile is somewhat different: pregnancy is an absolute contraindication, and hormone-sensitive cancers carry the same concerns. There are no testosterone products currently approved specifically for women in most countries, so prescribing is off-label, which adds a layer of complexity.
For transgender men, the contraindication list overlaps substantially with that for cisgender men, but pregnancy-related concerns take on additional practical importance. Testosterone does not reliably prevent pregnancy in people with ovaries and a uterus. If a transgender man on testosterone becomes pregnant, the testosterone must be stopped due to the risk of fetal harm. Guidelines recommend discontinuing testosterone before attempting pregnancy, but the exact washout period needed to ensure safety has not been firmly established.19PubMed Central. Pregnancy in transgender men Clinicians working in gender-affirming care are generally well aware of these issues, but it’s worth raising them explicitly if your healthcare provider doesn’t.
Drug Interactions Worth Knowing About
Testosterone itself doesn’t have a long list of dangerous drug interactions in the way that, say, blood thinners or certain antibiotics do. But there are a few that matter. If you take anticoagulant medications like warfarin, testosterone can alter coagulation parameters. One randomized study found that testosterone therapy shifted multiple clotting markers in an anticoagulant direction, which could theoretically amplify the effect of blood thinners and increase bleeding risk.20PubMed Central. Testosterone therapy increases the anticoagulant potential in men with opioid-induced hypogonadism: a randomized, placebo-controlled study If you’re on warfarin or similar medications, more frequent INR monitoring is warranted when starting or adjusting testosterone.
Testosterone can also affect blood sugar control in men with diabetes, typically improving insulin sensitivity and lowering glucose levels. That’s generally a positive effect, but it means diabetic medications may need dose adjustment to avoid hypoglycemia. Corticosteroids taken alongside testosterone can compound fluid retention. And opioid medications, ironically, are themselves a common cause of low testosterone, so the interaction runs both directions: opioids suppress testosterone production, and testosterone therapy in opioid users requires attention to the combined effect on mood, pain perception, and hormonal balance.