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PDE5 inhibitorPrescription only · Schedule H

Sildenafil

Uses, side effects, interactions and warnings

Reviewed by Dr. Vikram Sethi, DNB (Urology) · Updated
Generic nameSildenafil
Drug classPDE5 inhibitor
FormOral tablet
PrescriptionRequired
Starts working30–60 minutes
Lasts up to4–6 hours
Quick answer

Sildenafil is a prescription medicine for erectile dysfunction. Taken about an hour before sex, it improves blood flow to the penis so an erection is possible with sexual stimulation. It works for around 4 to 6 hours and must never be combined with nitrate heart medicines.

What is sildenafil used for?

  • Erectile dysfunction
  • Pulmonary arterial hypertension (lower doses, under specialist care)

How does sildenafil work?

Sildenafil blocks the PDE5 enzyme, which lets the blood vessels in the penis relax and fill with blood when you are sexually aroused. It does not cause an erection without stimulation and does not change desire.

How is sildenafil taken?

Tablets come in 25 mg, 50 mg and 100 mg strengths. It is usually taken as needed, about 1 hour before sex. A heavy, fatty meal can delay its effect. Your doctor will decide the right strength. Do not take more than one dose in 24 hours.

What are the side effects of sildenafil?

Common
  • Headache
  • Flushing
  • Indigestion
  • Stuffy nose
  • Temporary blue-tinted or blurred vision
Get medical help right away
  • Erection lasting more than 4 hours
  • Sudden loss of vision or hearing
  • Chest pain, irregular heartbeat or fainting
  • Severe allergic reaction

Which medicines interact with sildenafil?

Nitrates (nitroglycerin, isosorbide)AvoidCan cause a dangerous drop in blood pressure.
RiociguatAvoidRisk of severe low blood pressure.
Alpha-blockers (tamsulosin, doxazosin)CautionMay cause dizziness on standing. Doses may need adjusting.
Ritonavir, ketoconazole, clarithromycinCautionRaise sildenafil levels; a lower dose is usually needed.
AlcoholCautionHeavy drinking increases dizziness and can worsen erections.

Who should be careful with sildenafil?

Tell your doctor if you have heart disease, recent heart attack or stroke, very low or uncontrolled blood pressure, liver or kidney problems, an eye condition such as retinitis pigmentosa, or a blood disorder such as sickle cell anaemia.

Frequently asked questions

How long before sex should I take sildenafil?

Usually about 1 hour before. It can start working in 30 minutes, but a heavy meal may slow it down.

Is sildenafil the same as Viagra?

Yes. Viagra is a brand name for sildenafil. Generic versions contain the same medicine.

Can I take sildenafil every day?

Sildenafil is normally taken only when needed. If you need daily treatment, your doctor may suggest low-dose tadalafil instead.

This information does not replace advice from your doctor or pharmacist. SexologistIndia.com does not sell medicines.