Other significant adverse effects of testosterone supplementation include acceleration of pre-existing prostate cancer growth in individuals who have undergone androgen deprivation; increased hematocrit , which can require venipuncture in order to treat; and, exacerbation of sleep apnea .  Adverse effects may also include minor side-effects such as acne and oily skin, as well as, significant hair loss and/or thinning of the hair, which may be prevented with 5-alpha reductase inhibitors ordinarily used for the treatment of benign prostatic hyperplasia , such as finasteride .  Exogenous testosterone may also cause suppression of spermatogenesis , leading to, in some cases, infertility.  It is recommended that physicians screen for prostate cancer with a digital rectal exam and prostate-specific antigen (PSA) level before starting therapy, and monitor PSA and hematocrit levels closely during therapy. 
The breakdown and elimination of vardenafil from the body is inhibited by erythromycin , clarithromycin ( Biaxin ), ketoconazole ( Nizoral ), itraconazole ( Sporanox ), indinavir ( Crixivan ), ritonavir ( Norvir ), atazanavir ( Reyataz ), grapefruit juice. Therefore, these drugs increase the concentration of vardenafil in the blood and should not be combined with vardenafil. Vardenafil reduces the concentration of ritonavir and indinavir and may reduce the effect these drugs. Vardenafil increases heart rate and also exaggerates blood pressure lowering effects of nitrates (for example, nitroglycerine). In patients with chest pain ( angina ), particularly those who take nitrates,, vardenafil can cause chest pain by increasing heart rate and lowering blood pressure . Therefore, patients with angina should not use vardenafil. Vardenafil also exaggerates the blood pressure lowering effects of alpha-blocking drugs, for example, terazosin ( Hytrin ), and should not be used by individuals who also use alpha-blockers. Vardenafil also adds to the blood pressure reducing effect of other medications.