Several prescription medications adversely affect male potency, with some resulting in decreased sex drive and/or loss of erectile ability. The most common are antihypertensive drugs such as beta-blockers, diuretics, calcium channel blockers, and those acting centrally on the brain; some sedatives; GnRH (Gonadotropin releasing hormone) agonists used to treat advanced prostate cancer; 5-alpha reductase (Proscar or Avodart) for BPH treatment; and female hormones and antiandrogens. Among other medications associated with ED are H2 antagonists used for peptic ulcer, selective serotonin reuptake inhibitors and some other antidepressants, amphetamines, antiepileptics, and antipsychotics.
Certain over-the-counter drugs - for example, chronic use of vasoconstricting nasal decongestants - have been implicated in the development of sexual dysfunction. Use of illicit drugs (marijuana, cocaine, etc.) can cause ED as well. Small amounts of cocaine may produce sustained erections and delayed ejaculation, but chronic use of cocaine and/or opiates may lead to sexual dysfunction.
As for alcohol, minimal or moderate consumption may increase sexual enjoyment in about 45% of men and about 70% of women. Sexual arousal with alcohol consumption is usually affected by the individual's beliefs regarding alcohol's effect. However, chronic alcoholism, or even simply drinking large quantities of alcohol, may lead to ED, with decreased serum testosterone and increased female hormones. It may block the release of the pituitary and testicular hormones and affect the metabolism of the female hormone estrogen (in the form of estradiol) in the liver.