·         Anyone who takes medication with nitrates – whether taken regularly or as needed – should never take Viagra. Taking Viagra with nitrate medicines, or even recreational drugs containing nitrates, can cause your blood pressure to suddenly drop to unsafe levels. Mixing Viagra with nitrates can cause dizziness, fainting, even heart attacks and strokes. Many prescription drugs that are used to treat angina (chest pain due to heart disease) contain nitrates. Examples include: nitroglycerin, isosorbide mononitrate and isosorbide dinitrate. Amyl nitrate and nitrite (referred to as the recreational drug “poppers”) also contain nitrates.

·         Anyone who takes medicines called alpha-blockers for the treatment of high blood pressure should consult with their doctor, because blood pressure can suddenly drop, causing a person to get dizzy or faint.

·         Anyone taking a protease inhibitor should consult with their doctor regarding dosage of Viagra.

·         Viagra should not be taken with any other medical treatments that cause erections. This includes pills, medicines injected or inserted into the penis, implants or vacuum pumps.