A review found that testosterone supplements may be used to treat male sexual dysfunctions like erectile dysfunction, but only in hypogonadal men.

Reviewers searched databases including Medline, Embase, and Cochrane and analyzed data from 41 out of 1702 reports from the databases.  They found testosterone supplementation improved erectile function and other aspects of male sexual response in hypogonadal patients.

The authors cautioned there may be some biases present in the publications.  Only those trials sponsored by pharmaceutical companies still showed the desired effects of testosterone supplements on erectile function and libido components after potential biases were considered. 

Testosterone supplements may also improve the outcome resulting from medications like phosphodiesterase type 5 inhibitors (PDE5is).   PDE5 inhibitors such as Viagra (sildenafil), Cialis (tadalafil), and Levitra (vardenafil) are typically indicated for the treatment of erectile dysfunction.  (David Liu)

Source: Corona G, Isidori AM, Buvat J, Aversa A, Rastrelli G, Hackett G, Rochira V, Sforza A, Lenzi A, Mannucci E, Maggi M. Testosterone supplementation and sexual function: a meta-analysis study.  J Sex Med. 2014 Jun;11(6):1577-92. doi: 10.1111/jsm.12536. Epub 2014 Apr 4.