Testosterone therapy improves heart risk markers but raises an arrhythmia flag

Testosterone replacement therapy is a standard treatment for men with hypogonadism, with potential benefits spanning sexual function, body composition, bone mineral density, mood and metabolic health. Its cardiovascular safety, however, has been argued over for years, with conflicting evidence leaving both doctors and patients uncertain whether treatment protects the heart, harms it, or does neither. Because the men most likely to be prescribed testosterone are middle-aged and older, exactly the group in whom cardiovascular disease accumulates, settling this question matters enormously. This review pulled together the randomised trial evidence to assess that safety profile directly.

The authors searched PubMed, Web of Science, EMBASE and the Cochrane Library for randomised controlled trials published up to July 2024, following Cochrane methods for pooling trial results. Thirty-one trials qualified, covering 9,437 middle-aged and older men, with treatment durations ranging from 40 days to 36 months. They pooled outcomes covering blood lipids, exercise treadmill testing, carotid artery wall thickness and nonfatal cardiovascular events, comparing testosterone treatment against placebo throughout.

Testosterone therapy lowered total cholesterol by about 10.20 mg/dL, triglycerides by about 7.03 mg/dL and LDL cholesterol by about 6.64 mg/dL compared with placebo, while HDL cholesterol did not change significantly. Men on treatment lasted about 67.37 seconds longer on treadmill testing before showing a standard ECG sign of restricted blood flow to the heart, and over 12 to 36 months their carotid artery wall thickness fell by 0.03 mm. The notable exception ran the other way: across 6,598 participants, arrhythmias were more common on testosterone, with odds about 1.58 times those on placebo.

This lands in the middle of a genuinely contested area. Earlier evidence on testosterone and the heart has pointed in both directions, and this pooled analysis suggests the risk-factor picture, lipids, exercise tolerance and artery wall thickness, tilts favourable in men with low or low-normal testosterone. The arrhythmia signal complicates any clean conclusion and echoes ongoing safety debates. The authors themselves state that the clinical significance of that signal remains uncertain, which leaves the key open question: whether better risk markers translate into fewer actual cardiovascular events over the long term.

For a man considering or already on testosterone therapy for genuinely low levels, this is a reason to see the cardiovascular story as more nuanced than either the scare headlines or the clinic marketing suggest. The pooled trials point to improved cholesterol numbers and artery measures, not the across-the-board heart danger sometimes feared, but they also surface a rhythm signal that has not been explained away. It is information for a conversation with a doctor, not a verdict in either direction, and it applies to men with low or low-normal testosterone rather than to healthy men chasing higher levels.