Call your doctor immediately if you experience dizziness or feel nauseous during sexual activity, or develop pain, numbness, tingling in your chest, arms, neck, or jaw. Do not take Viagra if you are also taking a nitrate drug (such as nitroglycerin or isosorbide dinitrate/mononitrate) for chest pain or heart problems. Do not take Viagra with recreational drugs such as “poppers”. Taking these substances together can cause a sudden and dangerous drop in blood pressure. 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 …