EvidenceAStrongGood randomized trials in people that agree, with no serious weaknesses. New studies are unlikely to change the answer.
In middle-aged and older men with low testosterone, treatment did not raise the risk of heart attack, stroke or heart death over about 2 years. Atrial fibrillation (an irregular heartbeat) and blood clots in the lungs were more common.
Who it's for
Men with diagnosed low testosterone, including those with heart disease risk; not shown to help others.
What to expect
No added heart attack, stroke or heart death risk over roughly 2 to 3 years.
Watch out for
More irregular heartbeat, lung clots and kidney injury; long-term safety is unknown.
Heart events were about as common on testosterone as on placebo
Out of 100 men in each group, this many had a major heart event during the trial.
7 in 100
Testosterone gel
7.3 in 100
Placebo gel
had the outcomeDifference between the first two groups: 0.3 in 100 people
Heart events were about as common on testosterone as on placebo
Figure 4. Forest plots of placebo-controlled randomized trials examining the pooled effects of testosterone therapy on cardiovascular-related events by source of funding: upper panel funded…
The FDA is removing the boxed warning about increased heart risk from all testosterone products, citing the TRAVERSE trial, and keeps its limit on use for age-related low testosterone1Guideline · 2025FDA issues class-wide labeling changes for testosterone productsResults from the TRAVERSE trial were submitted in 2023, concluding that there was no increase in the risk of adverse cardiovascular outcomes in men using testosterone for hypogonadism.US Food and Drug Administration. The Endocrine Society advises against starting testosterone after a heart attack or stroke in the last 6 months, or with uncontrolled heart failure or a clotting disorder2Guideline · 2018Testosterone Therapy in Men With HypogonadismIt recommends against starting testosterone in men planning to have children soon, or with breast or prostate cancer, a raised PSA without further urological evaluation, a high hematocrit, untreated severe sleep apnea, uncontrolled heart failure, a heart attack or stroke in the last 6 months, or a clotting disorder.Endocrine Society.
What the studies show
TRAVERSE, a trial of 5,246 men aged 45 to 80 with low testosterone and existing or high risk of heart disease, used a daily gel or a dummy pill (placebo A dummy treatment that looks like the real one, so people can't tell which they got.). Heart death, nonfatal heart attack or stroke occurred in 7.0% on testosterone and 7.3% on placebo, over about 33 months of follow-up3Randomized trial · 2023 · 5,246 peopleCardiovascular Safety of Testosterone-Replacement Therapy.In men with hypogonadism and preexisting or a high risk of cardiovascular disease, testosterone-replacement therapy was noninferior to placebo with respect to the incidence of major adverse cardiac events. (Funded by AbbVie and others; TRAVERSE ClinicalTrials.gov number, NCT03518034.).N Engl J Med.
In the same trial, atrial fibrillation, acute kidney injury and lung clots were more frequent with testosterone3Randomized trial · 2023 · 5,246 peopleCardiovascular Safety of Testosterone-Replacement Therapy.In men with hypogonadism and preexisting or a high risk of cardiovascular disease, testosterone-replacement therapy was noninferior to placebo with respect to the incidence of major adverse cardiac events. (Funded by AbbVie and others; TRAVERSE ClinicalTrials.gov number, NCT03518034.).N Engl J Med.
A pooled analysis of 17 trials with individual data (3,431 men, average 9.5 months) found heart events in 7.5% on testosterone and 7.2% on placebo, a difference small enough to be chance5Meta-analysis · 2022 · 5,601 peopleAdverse cardiovascular events and mortality in men during testosterone treatment: an individual patient and aggregate data meta-analysis.We found no evidence that testosterone increased short-term to medium-term cardiovascular risks in men with hypogonadism, but there is a paucity of data evaluating its long-term safety. Long-term data are needed to fully evaluate the safety of testosterone.Lancet Healthy Longev,7Meta-analysis · 2024 · 3,431 peopleThe effects and safety of testosterone replacement therapy for men with hypogonadism: the TestES evidence synthesis and economic evaluation.Our findings do not support a relationship between testosterone replacement therapy and cardiovascular/cerebrovascular events in the short-to-medium term. Testosterone replacement therapy improves sexual function and quality of life without adverse effects on blood pressure, serum lipids or glycaemic markers.Health Technol Assess. Deaths were too few to judge7Meta-analysis · 2024 · 3,431 peopleThe effects and safety of testosterone replacement therapy for men with hypogonadism: the TestES evidence synthesis and economic evaluation.Our findings do not support a relationship between testosterone replacement therapy and cardiovascular/cerebrovascular events in the short-to-medium term. Testosterone replacement therapy improves sexual function and quality of life without adverse effects on blood pressure, serum lipids or glycaemic markers.Health Technol Assess.
An older review of 27 smaller trials (2,994 men) linked testosterone to more heart-related events. The rise was seen in trials not funded by industry, not in industry-funded ones4Meta-analysis · 2013Testosterone therapy and cardiovascular events among men: a systematic review and meta-analysis of placebo-controlled randomized trials.The effects of testosterone on cardiovascular-related events varied with source of funding. Nevertheless, overall and particularly in trials not funded by the pharmaceutical industry, exogenous testosterone increased the risk of cardiovascular-related events, with corresponding implications for the use of testosterone…BMC Med. A newer pooled review found no difference in major heart events, and the extra irregular heartbeats outside TRAVERSE could be chance10Meta-analysis · 2024 · 310 peopleCardiovascular safety of testosterone replacement therapy in men: an updated systematic review and meta-analysis.46]). Similarly, no relationship between endogenous T levels and AF incidence was observed after the adjustment for confounders Available data confirm that TRT is safe and it is not related to an increased CV risk.Expert Opin Drug Saf.
A trial of 209 frail older men with mobility limits stopped early. 23 men on testosterone had heart-related problems versus 5 on placebo. The authors said its small size and unusual group limit wider conclusions6Randomized trial · 2010 · 209 peopleAdverse events associated with testosterone administration.In this population of older men with limitations in mobility and a high prevalence of chronic disease, the application of a testosterone gel was associated with an increased risk of cardiovascular adverse events. The small size of the trial and the unique population prevent broader inferences from being made about the…N Engl J Med.
In a 12-month trial of 138 older men with data, artery plaque grew more on testosterone than on placebo. The clinical meaning is unclear9Randomized trial · 2017 · 788 peopleTestosterone Treatment and Coronary Artery Plaque Volume in Older Men With Low Testosterone.Among older men with symptomatic hypogonadism, treatment with testosterone gel for 1 year compared with placebo was associated with a significantly greater increase in coronary artery noncalcified plaque volume, as measured by coronary computed tomographic angiography. Larger studies are needed to understand the…JAMA.
These figures compare groups, so the gain or harm for one person depends on their starting risk.
Key studies
Study
Who
What it found
Trial, 20233Randomized trial · 2023 · 5,246 peopleCardiovascular Safety of Testosterone-Replacement Therapy.In men with hypogonadism and preexisting or a high risk of cardiovascular disease, testosterone-replacement therapy was noninferior to placebo with respect to the incidence of major adverse cardiac events. (Funded by AbbVie and others; TRAVERSE ClinicalTrials.gov number, NCT03518034.).N Engl J Med
5,246 men with low testosterone, heart risk
Heart events 7.0% vs 7.3% on placebo
Pooled trial data, 20225Meta-analysis · 2022 · 5,601 peopleAdverse cardiovascular events and mortality in men during testosterone treatment: an individual patient and aggregate data meta-analysis.We found no evidence that testosterone increased short-term to medium-term cardiovascular risks in men with hypogonadism, but there is a paucity of data evaluating its long-term safety. Long-term data are needed to fully evaluate the safety of testosterone.Lancet Healthy Longev
3,431 men, 17 trials
Heart events 7.5% vs 7.2%; no clear difference
Trial, 20106Randomized trial · 2010 · 209 peopleAdverse events associated with testosterone administration.In this population of older men with limitations in mobility and a high prevalence of chronic disease, the application of a testosterone gel was associated with an increased risk of cardiovascular adverse events. The small size of the trial and the unique population prevent broader inferences from being made about the…N Engl J Med
209 older men, limited mobility
More heart problems on testosterone; stopped early
Trial, 20179Randomized trial · 2017 · 788 peopleTestosterone Treatment and Coronary Artery Plaque Volume in Older Men With Low Testosterone.Among older men with symptomatic hypogonadism, treatment with testosterone gel for 1 year compared with placebo was associated with a significantly greater increase in coronary artery noncalcified plaque volume, as measured by coronary computed tomographic angiography. Larger studies are needed to understand the…JAMA
138 older men
More plaque growth over 12 months
Review of 27 trials, 20134Meta-analysis · 2013Testosterone therapy and cardiovascular events among men: a systematic review and meta-analysis of placebo-controlled randomized trials.The effects of testosterone on cardiovascular-related events varied with source of funding. Nevertheless, overall and particularly in trials not funded by the pharmaceutical industry, exogenous testosterone increased the risk of cardiovascular-related events, with corresponding implications for the use of testosterone…BMC Med
2,994 mostly older men
More heart events, mainly in non-industry trials
Safety
In a 2-year trial, blood thickness (hematocrit) rose above a safety limit in 22% on testosterone versus 1% on placebo. Serious side effects occurred in 10.9% versus 7.4%12Randomized trial · 2021 · 504 peopleTestosterone treatment to prevent or revert type 2 diabetes in men enrolled in a lifestyle programme (T4DM): a randomised, double-blind, placebo-controlled, 2-year, phase 3b trial.Testosterone treatment for 2 years reduced the proportion of participants with type 2 diabetes beyond the effects of a lifestyle programme. Increases in haematocrit might be treatment limiting. Longer-term durability, safety, and cardiovascular effects of the intervention remain to be further investigated.Lancet Diabetes Endocrinol. The Endocrine Society advises against testosterone with prostate or breast cancer, high hematocrit, or untreated severe sleep apnea2Guideline · 2018Testosterone Therapy in Men With HypogonadismIt recommends against starting testosterone in men planning to have children soon, or with breast or prostate cancer, a raised PSA without further urological evaluation, a high hematocrit, untreated severe sleep apnea, uncontrolled heart failure, a heart attack or stroke in the last 6 months, or a clotting disorder.Endocrine Society. The label says to check for blood clots if leg pain, swelling or sudden breathlessness occur13Guideline · 2025Testosterone: FDA drug label (prescribing information)Warnings: To date, epidemiologic studies and randomized controlled trials have been inconclusive for determining the risk of major adverse cardiovascular events (MACE), such as non-fatal myocardial infarction, non-fatal stroke, and cardiovascular death, with the use of testosterone compared to non-use. Some studies,…US Food and Drug Administration.
What we don't know
Long-term heart safety beyond about 3 years5Meta-analysis · 2022 · 5,601 peopleAdverse cardiovascular events and mortality in men during testosterone treatment: an individual patient and aggregate data meta-analysis.We found no evidence that testosterone increased short-term to medium-term cardiovascular risks in men with hypogonadism, but there is a paucity of data evaluating its long-term safety. Long-term data are needed to fully evaluate the safety of testosterone.Lancet Healthy Longev.
Whether the extra plaque growth leads to more heart attacks later9Randomized trial · 2017 · 788 peopleTestosterone Treatment and Coronary Artery Plaque Volume in Older Men With Low Testosterone.Among older men with symptomatic hypogonadism, treatment with testosterone gel for 1 year compared with placebo was associated with a significantly greater increase in coronary artery noncalcified plaque volume, as measured by coronary computed tomographic angiography. Larger studies are needed to understand the…JAMA.
Written by AI from the studies listed, without review by a clinician, and graded with the GRADE method. It can be wrong, so check the studies it cites. Education, not medical advice.