Erectile dysfunction is often the presenting symptom of a number of diseases such as arteriosclerosis, diabetes, hypertension, low testosterone, many neurological disorders, and much more according to a University of Adelaide study that was published in the March 2014 issue of the Journal of Sexual Medicine.
There are an amazing number of drugs that can cause ED that include diuretics, SSRI antipressants, antiseizure medications, antihistamines, NSAIDs, muscle relaxants, drugs that treat Parkinson's disease and many others.
Drugs used to treat ED, such as Viagra, Cialis, and Levitra work by regulating blood flow to the penis and are often effective, but have a wide range of possible side effects that include headache, flushing, indigestion, impaired vision, priaprism (sustained erection), hypotension, stroke, and even sudden hearing loss.