Viagra vs Cialis
C₂₂H₃₀N₆O₄S
Sildenafil (Viagra)
Sexual Health
VS
C₂₂H₁₉N₃O₄
Tadalafil (Cialis)
Sexual Health
Viagra (sildenafil) and Cialis (tadalafil) are the two erectile-dysfunction drugs that changed medicine — same mechanism, different clocks. Viagra works for 4–6 hours and wants planning; Cialis lasts up to 36 hours and earned the nickname 'the weekend pill.'
Viagra vs Cialis — side by side
| Viagra | Cialis | |
|---|---|---|
| What it is | PDE5 inhibitor; first ED drug (1998) | PDE5 inhibitor; second-generation (2003) |
| How long it lasts | 4–6 hours | Up to 36 hours |
| Onset | 30–60 min, faster on empty stomach | 30–45 min, food has less effect |
| Planning style | Take before the moment — 'the date drug' | Take Friday, covered through Sunday — 'the weekend pill' |
| Daily version | Not typically; on-demand dosing | Low-dose daily (2.5–5 mg) approved for continuous coverage |
| Second approvals | ED | ED + benign prostatic hyperplasia (daily dose) |
| Side effects | Headache, flushing, nasal congestion, blue-tinted vision (temporary) | Same minus the blue vision; more back/muscle aches |
The verdict
Same engine, different schedules. Viagra is the on-demand classic — best when the timing is known. Cialis is the flexibility king — spontaneity across a weekend, plus a daily low-dose option that also treats prostate symptoms. Neither works without arousal, neither is addictive, and both share the one hard rule: never combine with nitrates (heart medication) — the blood-pressure collapse can be fatal. Counterfeit ED pills are a massive market; unregulated versions have contained everything from talc to amphetamines.
?Frequently asked questions
Which works better, Viagra or Cialis?
Trials show equivalent effectiveness for ED. The choice is a lifestyle question: Cialis lasts ~6 times longer, so it wins for spontaneity; Viagra is fine when the timing is certain.
Is it safe to buy ED pills online?
Only from licensed pharmacies with a prescription. The WHO estimates a large share of online 'Viagra' is counterfeit — and fake ED pills have sent users to ERs with unpredictable ingredients.