Viagra vs Cialis vs Levitra: Which ED Pill Is Best?
How PDE5 Inhibitors Work
PDE5 inhibitors work by blocking the enzyme phosphodiesterase type 5, which breaks down cyclic guanosine monophosphate (cGMP) — the molecule responsible for relaxing smooth muscle in the penis and allowing blood flow. By inhibiting PDE5, these medications allow cGMP to accumulate, resulting in improved blood flow and firmer erections.
Important: PDE5 inhibitors require sexual stimulation to work. They do not cause spontaneous erections.
Head-to-Head Comparison
Sildenafil (Viagra)
- Onset: 30–60 minutes
- Duration: 4–6 hours
- Best taken: On an empty stomach (high-fat meals can delay onset)
- Dosages: 25mg, 50mg, 100mg
- Key advantage: The most extensively studied ED medication with over 25 years of clinical data
- Considerations: Must be timed before sexual activity; food can reduce effectiveness
Tadalafil (Cialis)
- Onset: 30 minutes (can work as fast as 15 minutes for some men)
- Duration: Up to 36 hours
- Best taken: Any time — food does not affect absorption
- Dosages: 2.5mg, 5mg (daily), 10mg, 20mg (as needed)
- Key advantage: Longest duration; available as a daily low-dose option for spontaneous readiness
- Considerations: Higher incidence of back pain and muscle aches
Vardenafil (Levitra)
- Onset: 25–60 minutes
- Duration: 4–5 hours
- Best taken: On an empty stomach or with a light meal
- Dosages: 5mg, 10mg, 20mg
- Key advantage: May be more effective for men with diabetes
- Considerations: Should not be taken with high-fat meals
Common Side Effects
All PDE5 inhibitors share similar side effects, including:
- Headache (most common, 10–16%)
- Flushing (5–12%)
- Nasal congestion (3–6%)
- Dizziness (2–3%)
- Visual disturbances (Sildenafil primarily — blue-tinted vision)
- Back pain and muscle aches (Tadalafil primarily)
Critical Safety Information
Do NOT take PDE5 inhibitors if you:
- Take nitrate medications (nitroglycerin, isosorbide) — the combination can cause a dangerous drop in blood pressure
- Take alpha-blockers for prostate issues — timing and dose adjustments may be needed
- Have had a recent heart attack or stroke
- Have severe liver disease
- Have certain rare eye conditions (NAION)
Always disclose your complete medication list and health history to your healthcare provider before starting any ED medication.
Which One Should You Choose?
| If you want... | Consider... |
|---|---|
| Longest window of effectiveness | Tadalafil (Cialis) |
| Most clinical data/track record | Sildenafil (Viagra) |
| Best option with diabetes | Vardenafil (Levitra) |
| Daily readiness without timing | Tadalafil 5mg daily |
| Lowest cost (generic available) | Sildenafil or Tadalafil |
The ReGenesis Approach
We don't prescribe a one-size-fits-all medication. During your comprehensive assessment, we evaluate your cardiovascular health, current medications, lifestyle, and treatment goals to recommend the PDE5 inhibitor — or alternative treatment — that's the best fit for you.
Ready to Take the Next Step?
Book a confidential assessment with a ReGenesis clinician.
Call 587.635.3414