What is the recommended dose of Viagra (sildenafil) for treating erectile dysfunction?

Recommended Dose of Viagra (Sildenafil) for Erectile Dysfunction

Start with 50 mg of sildenafil taken approximately 1 hour before sexual activity, then titrate to 100 mg if inadequate response or reduce to 25 mg if tolerability issues arise. 1

Standard Dosing Protocol

• The 50 mg starting dose represents the optimal balance between efficacy and tolerability for most men with erectile dysfunction. 1
• Take the medication approximately 1 hour before anticipated sexual activity, but not more than once daily. 1, 2
• Sexual stimulation is mandatory for the medication to work—this is not optional and accounts for many apparent treatment failures. 1

Dose Titration Strategy

• If 50 mg proves inadequate after proper use, increase to 100 mg (the maximum approved dose). 1
• The American Urological Association strongly recommends dose titration to optimize efficacy rather than abandoning treatment prematurely. 1
• Sildenafil demonstrates a dose-response relationship, with 50 mg superior to 25 mg in efficacy. 1
• Before declaring treatment failure, ensure at least 5 separate attempts at the maximum 100 mg dose. 1

Special Populations Requiring 25 mg Starting Dose

Reduce the starting dose to 25 mg in the following situations:

• Severe hepatic impairment (severe hepatic disease is generally a contraindication). 1
• Renal impairment requiring dose adjustment. 1
• Concurrent use of CYP3A4 inhibitors, including ritonavir, saquinavir, ketoconazole, erythromycin, or cimetidine. 1, 2
• Elderly patients may benefit from lower initial dosing. 2

Critical Safety Contraindications

• Concurrent nitrate use (organic nitrates, glyceryl trinitrate, isosorbide dinitrate) is an absolute contraindication due to potentially fatal hypotension. 1, 3
• Wait at least 24 hours after sildenafil before administering nitrates in emergency situations under close medical supervision. 1, 4
• High-risk cardiovascular conditions requiring cardiac stabilization before treatment include: unstable or refractory angina, uncontrolled hypertension, recent MI or stroke (within 2 weeks), and severe heart failure (NYHA class II or higher). 1

Common Pitfalls Leading to Treatment Failure

Many "treatment failures" result from incorrect usage rather than true medication ineffectiveness:

• Lack of sexual stimulation—the medication enhances but does not create erections without arousal. 1
• Taking with large meals, which delays absorption and reduces effectiveness. 1
• Improper timing—not allowing adequate time (approximately 1 hour) before sexual activity. 1
• Heavy alcohol use, which impairs erectile function and should be avoided. 4
• Inadequate trial—giving up before completing at least 5 attempts at maximum dose. 1

Expected Efficacy Outcomes

• Success rates of 69% for successful sexual intercourse attempts versus 35.5% with placebo. 1
• 73-88% improvement in erections versus 26-32% with placebo. 1
• Efficacy is maintained across various etiologies, including diabetes, cardiovascular disease, depression, spinal cord injury, and post-prostatectomy patients, though these populations may respond less robustly. 1, 5, 6

Common Adverse Effects

• The most frequent side effects are headache, flushing, dyspepsia, nasal congestion, and abnormal vision. 1, 2
• These effects are typically transient and mild-to-moderate in severity. 1, 2
• There is no increase in adverse events when using 100 mg compared to 50 mg. 7

Pharmacokinetics

• Sildenafil is rapidly absorbed with peak plasma concentrations within 1 hour of administration. 2
• The elimination half-life is 3 to 5 hours. 2
• Blood pressure is reduced transiently, but marked hypotension occurs with concurrent nitrate administration. 2, 3