Viagra 100mg Tablet is commonly prescribed for the following purposes:

• Treatment of erectile dysfunction (impotence) in adult men

• Management of pulmonary arterial hypertension (PAH)

• Improved exercise capacity in PAH patients

Viagra 100mg Tablet works by inhibiting the PDE5 enzyme, which normally breaks down a substance called cGMP. When cGMP levels increase, the blood vessels in the penis relax, allowing more blood to flow in during sexual arousal—resulting in a firmer, longer-lasting erection.

For patients with PAH, Viagra 100mg Tablet relaxes the blood vessels in the lungs, reducing the pressure on the heart and improving physical activity levels.

You should inform your doctor about all medications, herbs, or supplements you are taking. Viagra 100mg Tablet may interact with:

• Nitrate medications (for chest pain): Risk of severe drop in blood pressure

• Alpha-blockers (for high blood pressure or prostate): May cause dizziness or fainting

• Ritonavir, ketoconazole, erythromycin: Can increase blood levels of sildenafil

• Other PDE5 inhibitors: Should not be used together

Avoid alcohol and grapefruit juice while using Viagra 100mg Tablet, as they may reduce its effectiveness or increase side effects.

• Onset of action: 30–60 minutes before sexual activity

• Duration of effect: Up to 4 hours

• Not effective without sexual stimulation

• Not a cure for ED or PAH, but helps manage symptoms effectively

• Available only with a valid prescription

• For erectile dysfunction: Take 1 tablet approximately 1 hour before planned sexual activity. Do not take more than one dose in 24 hours.

• For pulmonary arterial hypertension: Take as prescribed, usually three times a day, spaced 4–6 hours apart.

Take Viagra 100mg Tablet with a full glass of water. It may be taken with or without food, but high-fat meals may delay its effect.

Viagra 100mg tablet causes some side effects like all medications, although not everyone will experience them. 

Serious:

• Sudden vision loss or vision changes
• Sudden hearing loss or changes in hearing
• Prolonged and painful erection (priapism)
• Severe allergic reactions (rash, itching, swelling of the face, lips, tongue, or throat, difficulty breathing)
• Chest pain or heart-related symptoms

Common:

• Headache
• Flushing (reddening and warming of the face and skin)
• Upset stomach or indigestion
• Nasal congestion
• Dizziness or lightheadedness
• Diarrhea
• Nausea
• Back pain
• Muscle pain

• Take Viagra 100mg Tablet about 1 hour before sexual activity—it works best when taken on an empty stomach.

• Do not take more than one dose per day unless prescribed for pulmonary hypertension.

• Avoid alcohol and grapefruit juice while using Viagra 100mg Tablet—they may reduce its effectiveness or increase side effects.

• Inform your doctor if you have heart problems, low blood pressure, or are taking nitrate medications.

• Sexual stimulation is required for the medicine to work; it won't cause an erection just by taking it.

• If you experience vision changes, chest pain, or an erection lasting more than 4 hours, seek immediate medical help.

• Store Viagra 100mg Tablet in a cool, dry place away from direct sunlight.

1. Milpharm Limited, Electronic medicines compendium (emc), [Revised on Sept 2020] [Accessed on 25th July 2023], https://www.medicines.org.uk/emc/files/pil.7141.pdf
2. Pfizer, US Food and Drug Administration, [Revised on March 2014] [Accessed on 25th July 2023], https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/20895s039s042lbl.pdf