Sildenafil
"A strong pill for erection but with some side effects.

12.5mg works great (strong erection) 30 min-1h before and lasts for 3h-4h. Its easy to recover erection but can be lost sometimes.

Side effects (0h-4h):
- Stuffy nose

Side effects (4h-12h):
- Stomach discomfort, indigestion
- Sleepiness, trouble sleeping

Tried Levitra, not strong as Viagra but some side effects. 
I'm now trying Avanafil (25mg) and by now no side effects (maybe because it PDE5 highly selectivity) but lasts only 2h."