Mydlo added one more word of caution: "Don't use ED medications -- Viagra, Cialis -- if you don't need them. Erections that last longer than four hours -- priapism -- can cause permanent scar tissue and permanent impotence. It's not a good idea to use these drugs casually."
To learn more about erectile dysfunction and how to prevent it, visit the National Institute of Diabetes and Digestive and Kidney Diseases.
SOURCES: Larry Lipshultz, M.D., chief, male reproductive medicine, and professor, urology, Baylor College of Medicine, Houston; Jack Mydlo, M.D., professor and chairman, urology, Temple University School of Medicine and Hospital, Philadelphia; March 2006 Tobacco Control; American Journal of Epidemiology