Do not take VIAGRA (sildenafil citrate) if you: take any medicines called nitrates, often prescribed for chest pain, or guanylate cyclase stimulators like Adempas (riociguat) for pulmonary hypertension. Your blood pressure could drop to an unsafe level are allergic to sildenafil, as contained in VIAGRA and REVATIO, or any of the ingredients in VIAGRADiscuss your health with your doctor to ensure that you are healthy enough for sex. If you experience chest pain, dizziness, ornausea during sex, seek immediate medical help.VIAGRA can cause serious side effects. Rarely reported side effects include: an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis sudden vision loss in one or both eyes. buy Xanax online in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy (NAION). Stop taking VIAGRA and call your healthcare provider right away if you have any sudden vision loss sudden hearing decrease or hearing loss. Some people may also have ringing in their ears (tinnitus) or dizziness. If you have these symptoms, stop taking VIAGRA and contact a doctor right awayBefore you take VIAGRA, tell your healthcare provider if you: have or have had heart problems such as a heart attack, irregular heartbeat, angina, chest pain, narrowing of the aortic valve, or heart failure have had heart surgery within the last 6 months have pulmonary hypertension have had a stroke have low blood pressure, or high blood pressure that is not controlled have a deformed penis shape have had an erection that lasted for more than 4 hours have problems with your blood cells such as sickle cell anemia, multiple myeloma, or leukemia have retinitis pigmentosa, a rare genetic (runs in families) eye disease have ever had severe vision loss, including an eye problem called NAION have bleeding problems have or have had stomach ulcers have liver problems have kidney problems or are having kidney dialysis have any other medical conditions