Testosterone lifted desire more reliably than it lifted erections
Pooled trials put erectile function up 2.31 points on the standard questionnaire. A later two-year trial in 1161 men found more desire and activity, and no erection difference at all.
What the study found
Desire and erections are not one outcome, and they split
Pooling 14 placebo-controlled trials, testosterone improved erectile function by 2.31 points on the standard erectile-function questionnaire. The largest trial since, two years in 1161 men, found more sexual activity and stronger desire and no separation at all on erections.
The caveat · Long trial took only heart-risk men
The two-year trial was nested inside a cardiovascular safety study, so every man in it had heart disease or a high risk of it. In the meta-analysis the gain shrank in men with diabetes or obesity, who are a large share of those seeking treatment. And 2.31 points sits close to the smallest difference a man with mild erectile dysfunction would notice.
What we don't know
Whether testosterone helps erections is unsettled. Pooled trials found a gain, largest in men starting lowest; two later long trials found none, in less deficient men on different questionnaires, so the split may be about who was studied.