Sildenafil or Viagra is an oral drug that facilitates an erection, thus may be useful in impotence.
Sildenafil or Viagra relaxes smooth muscle making penile erection possible, but sexual stimulation is required. It needs to be taken about an hour prior to anticipated sexual activity, in order to have sufficient blood levels.
Sildenafil or Viagra can cause headache, facial flushing, indigestion, and muscle aches. Some individuals taking higher doses have reported the development of colour blindness.
Sildenafil or Viagra was originally studied for use in angina, that is heart pain, thus has the potential to affect the cardiovascular system, and people with cardiovascular problems.
Sildenafil or Viagra has not been reported to interact with other drugs, however, it is new and used on an infrequent basis, thus more time is required to determine drug interactions. Recent information indicates that the drug cannot be used in conjunction with nitrates.
Br J Urol 1996;78:257
Ann Intern Med 1988;109:162
The relevant product monographs must be regarded as the appropriate sources of prescribing information.