The comparison
| Sildenafil (generic Viagra) | Tadalafil (generic Cialis) | |
|---|---|---|
| Starts working | 30–60 minutes | 30–60 minutes |
| Lasts | 4–6 hours | Up to 36 hours |
| Effect of food | A fatty meal delays it noticeably | Little to none |
| Effect of alcohol | Best kept to one or two drinks | Best kept to one or two drinks |
| Common doses | 25, 50, 100 mg as needed | 10, 20 mg as needed, or 2.5–5 mg daily |
| Daily option | No | Yes — the main advantage |
| Distinctive side effect | Blue tinge to vision, light sensitivity | Back and muscle ache, often next day |
| Nitrate waiting period | At least 24 hours | At least 48 hours |
Why the duration matters more than it sounds
On paper, 36 hours versus 6 hours is a specification. In practice it changes the character of the thing.
With sildenafil there is a clock. You take it, you wait, and there is a window. For some couples that is completely fine. For others — particularly where one partner is not aware of the medication, or where sex tends to happen when it happens — the scheduling becomes its own source of pressure, and pressure is the last thing this needs.
Tadalafil's long tail decouples the tablet from the event. Take it Friday evening and Saturday is simply available. Many men over 50 describe this as the thing that made sex feel normal again rather than medicated.
The daily dose, and the prostate bonus
Low-dose daily tadalafil — 2.5 or 5 mg — keeps a steady level in your blood so there is no dosing decision at all. You are simply someone who takes a small tablet each morning.
It is also approved for the urinary symptoms of an enlarged prostate: the weak stream, the getting up at night, the sense of not finishing. A great many men over 50 have both problems, and one small daily tablet addressing both is genuinely efficient. If that describes you, this is the option to raise by name.
Side effects, compared honestly
Both cause headache, flushing and a blocked nose, at broadly similar rates. Where they differ:
- Sildenafil is more associated with visual effects — a blue or bright tinge, light sensitivity — because it has some cross-activity with an enzyme in the retina. It is temporary and harmless, but it puts some men off.
- Tadalafil is more associated with back and muscle aching, often turning up twelve to twenty-four hours later and lasting a day or two. Nobody is entirely sure why. It usually settles with continued use.
Both share the serious warnings: an erection over four hours is an emergency, and sudden vision or hearing loss means stopping and seeking care. And both share the absolute contraindication with nitrates. Full safety detail.
So which one?
If you want a straight answer: for most men over 50, low-dose daily tadalafil is the better starting point, particularly if you also have urinary symptoms. It removes the timing problem, which is the part men actually find difficult.
Choose sildenafil instead if you want sex rarely enough that daily dosing feels wasteful, if cost is genuinely tight, or if you have tried tadalafil and the muscle ache was intolerable.
And if the first one you try does not work, trying the other is a reasonable next step before concluding this whole class has failed. Response is not perfectly consistent between them.