Testosterone

Is testosterone therapy safe?

For men with a confirmed testosterone deficiency, prescribed testosterone is safer than its reputation suggests. The question that worried regulators for a decade, whether it causes heart attacks and strokes, was largely answered by the TRAVERSE trial: among 5,198 men aged 45 to 80 with heart disease or high heart risk, 7.0% on testosterone gel and 7.3% on placebo had a heart attack, stroke or heart death. In 2025 the FDA removed cardiovascular risk language from testosterone labels.

The risks that remain are real, though. Testosterone thickens the blood, raises blood pressure, can stop sperm production, transfers from gel to children and partners, and is a Schedule IIIControlled substanceA medicine or drug that the law restricts because it can be misused or cause dependence. Countries group them into schedules or classes.More in the glossary drug that is widely misused. We score it 68, next to prednisone (66) and isotretinoin (67), and well below finasteride (81), another hormone-acting drug with no misuse potential.

This page covers testosterone replacement for men with low testosterone. Using it to build muscle is misuse, and the risks there are much higher.

What changed on the label in 2025 and 2026?

Two rounds of change in two years:

• March 2025: after TRAVERSE, the FDA removed "cardiovascular risk" warnings across testosterone products. Xyosted's boxed warningBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary on blood pressure increases was also removed, though blood pressure rises stay in the standard warnings section on all products. The trial results, including more blood clots and atrial fibrillation, were added.
• June 2026: HHS and the FDA asked manufacturers to make further changes: remove the statement that safety and effectiveness in age-related low testosterone have not been established, limit the prostate cancer contraindicationContraindicationA situation in which a medicine should not be used, because the risk clearly outweighs any benefit, such as a known allergy to it.More in the glossary to metastatic disease, and soften the warning on enlarged prostate. By October 2026, labels we checked still carried the old limitation, so these changes are requested, not yet in force.

Two boxed warnings remain. Gels warn about secondary exposure of children. Aveed, a long-acting injection, warns of oil embolism in the lungs and severe allergic reactions, and is only given in clinics with 30 minutes of observation.

What are the side effects?

TRAVERSE gives the clearest numbers for gel at an average of 65 mg a day:

Event	Testosterone	Placebo
Heart attack, stroke or heart death	7.0%	7.3%
Arrhythmias needing treatment	5.2%	3.3%
Atrial fibrillation	3.5%	2.4%
Acute kidney injury	2.3%	1.5%
Bone fracture	3.5%	2.5%
Blood clots (DVT or pulmonary embolism)	1.7%	1.2%

Other label warnings:

• High red cell count (polycythaemia): the most common reason to pause treatment. The Xyosted label asks for haematocrit checks about every 3 months.
• Blood pressure: testosterone can raise it; labels advise against use with uncontrolled high blood pressure.
• Fertility: very low sperm counts are possible, because outside testosterone switches off the body's own production.
• Prostate: labels still contraindicate known or suspected prostate cancer and ask for PSA monitoring.
• Others: sleep apnoea, fluid retention, acne and breast enlargement.

Label doses

Doses depend on the product and blood levels, which must be measured on two separate mornings before starting:

• Gel 1.62%: 40.5 mg once a day on the shoulders and upper arms, adjusted between 20.25 mg and 81 mg based on morning blood levels at about 14 and 28 days.
• Testosterone cypionate injection: 50 to 400 mg deep into the muscle every 2 to 4 weeks.
• Xyosted: 75 mg under the skin of the abdomen once a week, adjusted after 6 weeks.

Gel transfer: the warning most users forget

Children who touched a parent's unwashed skin or clothing have developed enlarged genitals, pubic hair, aggressive behaviour and advanced bone age; in a few cases the genital changes did not fully reverse. Women can develop acne and other signs of virilisation. To prevent it, wash your hands straight after applying, let the gel dry, cover the area with a shirt, and wash the skin before close contact. Injections and capsules do not carry this risk.

Abuse and dependence

Testosterone is a Schedule IIIControlled substanceA medicine or drug that the law restricts because it can be misused or cause dependence. Countries group them into schedules or classes.More in the glossary controlled substance in the US. Labels describe abuse by athletes and bodybuilders, often with other anabolic steroids, at doses far above replacement levels. Reported harms include heart attacks, heart muscle disease, strokes, liver injuryDrug-induced liver injuryLiver damage caused by a medicine, herbal product or supplement. It is usually rare and unpredictable, but it can be serious.More in the glossary, aggression and psychosis. People who stop high doses can have withdrawal lasting weeks or months, with depression, fatigue, craving, insomnia and low libido. The labels note that dependence has not been documented at approved doses for approved uses. Products bought online or at gyms have no quality checks. DHEA, sold as a supplement, is converted to sex hormones in the body and is not a safe substitute.

Who should be careful

Talk to your doctor or pharmacist before starting if you have heart disease, a past blood clot, high blood pressure, sleep apnoea, prostate problems or a high red cell count, or if you want to have children. Testosterone can increase the effect of warfarin, so clotting tests need checking, and people with diabetes may need less insulin. US testosterone products are approved for men, not women, and must not be used in pregnancy.

How we scored it

Track record (90) and interactions (82) are strong, and the overdose marginOverdose marginHow far a normal dose is from a harmful one. A wide margin means an accidental extra dose is unlikely to cause serious harm.More in the glossary (80) is wide. Dependence (50) reflects Schedule IIIControlled substanceA medicine or drug that the law restricts because it can be misused or cause dependence. Countries group them into schedules or classes.More in the glossary status and widespread misuse. Regulatory warnings (48) remain low because of the gel and Aveed boxed warningsBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary, even after the 2025 changes. Serious side effects (60), the heaviest factor, balance the reassuring heart attack data against clots, rhythm problems and polycythaemia. A lower score does not mean you should stop; talk to your prescriber first.