Viagra is the most popular and recognized medicine prescribed to patients unable to achieve and maintain a stable erection for a period of time long enough to have a sexual intercourse. If you are also using another medication for the treatment of erectile dysfunction tell your doctor about it to prevent serious complications. The drugs that you need to be especially cautious with are bosentan (Tracleer), blood thinners (warfarin), cimetidine, antibiotics (erythromycin or clarithromycin, doxazosin, prazosin, HIV medicines, antifungal medication (itraconazole or ketoconazole), carbamazepine, phenobarbital, phenytoin, rifampin, or rifabutin.
To make sure this medicine is efficient and works as it should it's recommended to avoid drinking alcohol simultaneously with using Viagra. Do not use any other drugs intended for the treatment of impotence (alprostadil, yohimbine) without previously talking to your health care provider. It's recommended to stop using this drug if you experience any of the following serious side effects of Viagra: irregular heartbeat, swelling in your limbs, general ill feeling, sudden vision loss, hearing loss or ringing in your hears, vision changes, or painful erection that lasts for longer than 4 hours.