Viagra vs Cialis - Comparing The Differences, Side Effects & More

By: Noah W Chung | PharmD

SaveHealth the prescription discount website explores Viagra vs Cialis. Viagra (sildenafil) and Cialis (tadalafil) are leading phosphodiesterase-5 (PDE5) inhibitors prescribed for erectile dysfunction (ED). Both enhance blood flow to the penis during sexual stimulation but differ significantly in duration, dosing flexibility, and lifestyle compatibility. Approved in 1998 and 2003 respectively, these medications have become cornerstone treatments for ED, with Cialis also FDA approved for benign prostatic hyperplasia (BPH). 

Viagra vs Cialis - Mechanism of Action 

Both drugs work by inhibiting PDE5, increasing cyclic guanosine monophosphate (cGMP) to relax penile smooth muscles and improve blood flow. Key similarities include: 

• Require sexual arousal for effectiveness 

• Contraindicated with nitrates due to blood pressure risks 

• Enhance natural erectile response without affecting libido 

Key Differences at a Glance 

Viagra vs Cialis - Effectiveness and Duration 

• Clinical Success Rates: Both demonstrate 67-89% effectiveness in clinical trials

• Duration Advantages: Cialis' 36-hour window earned it the nickname "weekend pill" Viagra's shorter duration may bene t those preferring precise timing

• Real-World Preferences: 60% of men prefer Cialis for spontaneity, while Viagra users appreciate its predictable 4 hour window

Cialis vs Viagra - Side Effect Comparison 

Common to Both: 

• Headaches (16-42% incidence)

• Flushing (2-19%)

• Nasal congestion (4-9%)

• Indigestion (2%)

Unique Profiles: 

Note: Both carry rare but serious risks of priapism (prolonged erection >4 hours) Dosage and Administration 

Viagra Protocol: 

• Take 1 hour before sex on empty stomach 

• Start with 50mg, adjust to 25-100mg 

• Max 1 dose/day 

Cialis Options: 

1. As Needed: 10-20mg 30 mins before activity 

2. Daily Use: 2.5-5mg for continuous readiness 

3. BPH Treatment: 5mg daily with consistent timing 

Critical Considerations: 

• Hepatic/renal impairment requires dose adjustments

• Avoid concurrent alpha-blockers without medical supervision (may lead to extreme dizziness, lightheadedness, fainting)

Special Considerations 

Lifestyle Factors:

• Cialis preferred for: 

  • Spontaneous sexual activity 

  • Patients who dine before intimacy 

• Viagra ideal for: 

  • Predictable scheduling 

  • Those avoiding daily medication 

BPH Management: 

Cialis uniquely treats both ED and urinary symptoms through: 

• Smooth muscle relaxation in prostate/bladder 

• Improved urinary flow rates (39% increase in clinical trials) 

Cialis vs Viagra - Drug Interactions and Contraindications 

Absolute Contraindications: 

• Concomitant nitrate use (angina medications) 

• Severe hepatic/renal impairment 

Key Interactions: 

Choosing the Right Medication  - Cialis vs Viagra

Consider Cialis If: 

• Spontaneity is important 

• You have concurrent BPH 

• Tolerating frequent dosing is challenging 

Consider Viagra If: 

• Predictable timing works for your routine 

• You prefer shorter-acting medication 

• Cost is a primary concern (generic sildenafil averages $2/dose)

Clinical Tip: 40% of non-responders to one PDE5 inhibitor benefit from switching to the other

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