viagra

Viagra is a brand-name prescription medication containing the active ingredient sildenafil citrate. It belongs to a class of drugs known as phosphodiesterase type 5 (PDE5) inhibitors. Viagra is primarily FDA-approved for the treatment of erectile dysfunction (ED) in men, though sildenafil is also prescribed under different brand names for pulmonary arterial hypertension (PAH).



How It Works



During sexual stimulation, Viagra works by inhibiting the PDE5 enzyme, which normally breaks down cyclic guanosine monophosphate (cGMP). By preventing this breakdown, the medication increases and maintains levels of cGMP, relaxing the smooth muscles and expanding blood vessels in the penis. This dramatically enhances blood flow, helping to achieve and sustain an erection. Viagra does not increase libido or cause an automatic erection; physical or psychological sexual arousal is entirely necessary for it to work. It typically becomes effective within 30 to 60 minutes and remains active in the body for up to 4 to 5 hours.



Common Dosages



Viagra is available as a blue, diamond-shaped film-coated tablet. It is typically prescribed in three primary strengths:

• 25 mg: Often recommended as a starting dose for older adults or individuals with pre-existing hepatic or renal impairment.

• 50 mg: The standard, most common starting dose for most adults, taken roughly one hour before sexual activity.

• 100 mg: The maximum single daily dose, prescribed if the 50 mg strength is ineffective and well-tolerated.



Critical Safety Warnings & Interactions



• The Nitrate Contraindication: Taking Viagra concurrently with nitrates (such as nitroglycerin, isosorbide dinitrate, or amyl nitrite "poppers") prescribed for chest pain or heart conditions is strictly contraindicated. Combining them can trigger a sudden, life-threatening drop in blood pressure.

• Cardiovascular Risks: Individuals with a history of recent stroke, myocardial infarction (heart attack), unstable angina, or severe cardiac disease must consult a physician, as sexual activity itself poses a strain on the cardiovascular system.

• Priapism: In rare instances, Viagra can cause a prolonged, painful erection lasting longer than 4 hours. This is a medical emergency that requires immediate intervention to prevent permanent tissue damage to the penis.

• Vision and Hearing Changes: Rarely, users may experience sudden vision loss in one or both eyes—a sign of Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)—or a sudden decrease or loss of hearing. Stop taking the medication immediately if these symptoms manifest.



Common Side Effects



Most side effects are mild and temporary, including headaches, facial flushing, dyspepsia (indigestion/upset stomach), nasal congestion, dizziness, and mild visual distortions (such as a temporary blue-green color tinge or blurred vision).