What is the recommended dose of Viagra (sildenafil)?

Recommended Dosage of Viagra (Sildenafil)

The recommended dose of Viagra (sildenafil) for erectile dysfunction is 50 mg taken approximately 1 hour before sexual activity, with the option to adjust to 25 mg or 100 mg based on efficacy and tolerability, and should not be taken more than once daily. 1

Initial Dosing and Adjustments

• Start with 50 mg taken approximately 1 hour before sexual activity 1
• Dose can be adjusted based on efficacy and tolerability:
  • Can be increased to 100 mg if 50 mg is insufficient 2, 1
  • Can be decreased to 25 mg if side effects occur 1, 3
• Should not be taken more than once daily 1, 4
• Take on an empty stomach for optimal absorption (high-fat meals can delay absorption) 2

Special Population Considerations

• Lower starting dose (25 mg) recommended for:
  • Elderly patients (>65 years) 1, 3
  • Patients with hepatic or renal impairment 2, 1
  • Patients taking CYP3A4 inhibitors (e.g., erythromycin, ketoconazole, cimetidine) 1, 4
• For patients taking ritonavir or other potent CYP3A4 inhibitors, even lower doses may be required 1

Efficacy Considerations

• Dose-related improvements in erectile function have been observed with sildenafil (50 mg vs. 25 mg shows improved efficacy) 2, 5
• Less additional benefit seen when comparing 100 mg vs. 50 mg 2, 5
• In clinical trials, approximately 69% of men reported improved erections with sildenafil compared to 35.5% with placebo 2, 5
• Efficacy is maintained in long-term (1-year) studies 1

Important Contraindications

• Absolute contraindication: Concurrent use with nitrates or nitric oxide donors due to risk of severe hypotension 2, 4, 3
• Use with caution in patients with:
  • Cardiovascular disease 2, 4
  • Recent myocardial infarction or stroke (within 6 months) 3
  • Unstable angina 3
  • Uncontrolled hypertension 3

Common Side Effects

• Most common side effects are transient and mild to moderate:
  • Headache (most common) 1, 3
  • Flushing 1, 3
  • Dyspepsia 1, 3
  • Nasal congestion 1, 3
  • Visual disturbances 1, 2

Clinical Pearls

• For maximum benefit, patients should be instructed to:
  • Take sildenafil approximately 1 hour before sexual activity 1, 4
  • Understand that sexual stimulation is necessary for the medication to work 2, 1
  • Avoid high-fat meals before taking the medication 2
• If initial treatment fails, assess for proper medication use and timing before concluding treatment failure 2
• Regular follow-up is recommended to assess efficacy, side effects, and changes in health status or medications 2