🧪 What Sildenafil Is
Sildenafil is a medicine in the PDE-5 inhibitor class.
It’s best known under the brand name Viagra, but many generic versions contain the same active ingredient.
🩺 What It’s Used For
✔ Erectile Dysfunction (ED)
Helps achieve and maintain an erection when sexually stimulated by increasing blood flow to the penis.
✔ Pulmonary Arterial Hypertension (PAH)
At different dosing regimens (lower doses taken multiple times daily), sildenafil is also used to lower blood pressure in the lungs under specialist care.
⚙️ How It Works
Sildenafil blocks the phosphodiesterase-5 (PDE-5) enzyme.
This allows nitric oxide to act longer, causing:
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Relaxation of blood vessels
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Increased blood flow to erectile tissue
Sexual stimulation is still required for it to work.
⏱️ Onset & Duration
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Onset: ~30–60 minutes
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Peak effect: ~1 hour
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Duration: ~4–6 hours
A high-fat meal can delay onset.
📦 Sildenafil 100 mg
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100 mg is the highest commonly prescribed single dose for ED
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Lower doses (25 mg or 50 mg) are often tried first
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Should not be taken more than once in 24 hours
⚠️ Safety Information (General)
🚫 Do NOT use with nitrates
Combining sildenafil with nitrate medicines (e.g. GTN spray, isosorbide) can cause a dangerous drop in blood pressure.
⚠️ Caution with other medicines
Interactions may occur with:
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Alpha-blockers (for blood pressure or prostate symptoms)
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Some antifungals and antibiotics
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HIV medicines
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Other ED treatments
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Alcohol (can worsen dizziness and low BP)
