Sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis) are medicines prescribed for erection difficulties caused by either physical or psychological problems. The drugs work only when the man is sexually aroused. The effect is usually seen within 15 - 45 minutes
Viagra should work up to 4 hours after you take it.
Cialis may work for up to 36 hours after you take it.
Cialis is usually taken only when needed, however, Cialis may also be taken daily (at a lower dose), regardless of when sexual activity is planned.
- Viagra Information for Consumers
- Viagra Information for Healthcare Professionals (includes dosage details)
- Side Effects of Viagra (detailed)
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