Sildenafil dosage guide: 50mg, 100mg and 150mg explained
Summary
What the different Sildenafil strengths mean, how onset and duration work, and the safety basics everyone should know before starting.
Last reviewed 3 June 2026 by the Kam4eu editorial team · Next review August 2027
Sildenafil is sold in several strengths — most commonly 50 mg, 100 mg and 150 mg — under generic names like Kamagra, Cenforce, Fildena and Sildamax. Here's what those numbers mean and the safety basics to understand before you start.
The common strengths
- 50 mg — a common starting dose. Many doctors recommend beginning here to see how you respond.
- 100 mg — the most widely sold strength.
- 150 mg — a higher strength that should only be used on medical advice.
Higher is not automatically better. The right dose is the lowest one that works for you, and taking more than recommended increases the chance of side effects without improving the result.
Onset and duration
Sildenafil typically begins working 30 to 60 minutes after taking it and lasts around 4 hours. A heavy or high-fat meal can delay onset, so it's often taken on a lighter stomach.
Safety basics
- Do not combine with nitrate medicines (used for chest pain) — this can cause a dangerous drop in blood pressure.
- Speak to a doctor first if you have heart, liver or kidney conditions, low blood pressure, or have had a stroke.
- Only take one dose in any 24-hour period.
- Always read the patient information leaflet supplied with your medicine.
Where to start
If you're new to Sildenafil, talk to a doctor or pharmacist about the right starting strength.
This is general information, not a prescription or medical advice. A qualified healthcare professional should guide your dose.
Official sources & further reading
Treatment options
Treatments discussed in this guide
Prescription-only medicines — speak to a doctor before use. Discreet delivery across the UK & Europe.
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