Silagra 100 mg contains sildenafil 100 mg, and its erectile-effect window is typically around 3–4 hours, although the strength and duration vary between people. Clinical data show an effect can persist for up to about 4 hours, with the response generally strongest earlier on. A few important points: It usually starts working in 30–60 minutes. It doesn't cause a continuous erection; ***** stimulation is needed. A heavy meal can delay its onset. 100 mg is the maximum recommended sildenafil dose and should not be taken more than once in 24 hours. Don't use it with nitrate medicines (such as nitroglycerin) because this can cause a dangerous blood-pressure drop. If you're mainly looking for longer duration, tadalafil (such as Tadarise/Tadasoft) generally lasts much longer than sildenafil—often up to 36 hours.