Both are effective. Both are PDE5 inhibitors. The right choice depends on how often you are sexually active, whether you also have urinary symptoms, and whether you prefer as-needed or continuous coverage. Here is the side-by-side.
| Factor | Sildenafil | Tadalafil |
|---|---|---|
| Brand name | Viagra | Cialis |
| Half-life | ~4 hours | ~17.5 hours |
| Duration of effect | 4–6 hours | Up to 36 hours |
| Onset (oral) | 30–60 minutes | 30–60 minutes |
| Onset (sublingual troche) | ~15–20 min | ~15–30 min |
| Affected by food | Yes (fatty meals delay oral) | No |
| Daily dosing approved | No | Yes (2.5–5 mg) |
| Also treats BPH | No | Yes |
| Common side effects | Headache, flushing, nasal congestion, visual color changes | Headache, back pain, muscle aches, nasal congestion |
| YourMD starting price | $45/month | $45/month |
No. Never combine PDE5 inhibitors. If switching from one to the other, wait at least 24 hours (sildenafil to tadalafil) or 48 hours (tadalafil to sildenafil) for the first drug to clear.
Some patients use daily low-dose tadalafil (2.5 mg) as baseline coverage and add occasional sildenafil on specific occasions when they want faster onset. This is an off-protocol approach that requires physician oversight — it should not be done without medical guidance. Discuss with your YourMD physician if this pattern appeals to you.
Not sure? Your YourMD physician will recommend during your free screening.
Medical disclaimer: Educational content, not medical advice. Page medically reviewed by Teja V. Surapaneni, MD, MS (NV, WA, OR, WY). Last reviewed: April 17, 2026