The half-life is approximately 4 hours. If is recommended that sexual stimulation commence from 30 to 60 minutes after Viagra is taken. Sildenafil, or Viagra, is excreted as metabolites from the body in feces and urine. Yes, a small percentage of the study group experienced headaches, nausea, facial flushing, diarrhea, urinary tract infection and visual changes to color sensitivity. While there is no direct evidence that Viagra caused the deaths, readers should be aware that sexual activity increases cardiac risk.
Male impotence is often a side effect of more serious cardiovascular problems.
There is evidence to suggest that Viagra may interact with other medications in such a way as to increase health risk. Men who have medical conditions, such as sickle cell anemia, leukemia, or multiple myeloma, or those with abnormally-shaped penis should also not take Viagra because of a possibility of producing a sustained erection. You must tell your doctor exactly what other medications you are taking. Many physicians are now recommending Viagra therapy begin with 25mg dosage, the minimum. Standard dose is 50mg.