Sildenafil

How it works

Sildenafil belongs to the PDE5 inhibitor class. It works by blocking the PDE5 enzyme responsible for breaking down cGMP in penile tissue, which lets smooth muscle there relax and blood flow rise once stimulation begins. That last part matters: sildenafil requires sexual arousal to work, so it won't produce an erection in your body on its own, no matter how much time has passed since your dose. The mechanism is identical at 50mg and 100mg; what changes at the higher dose is how much drug is available to occupy the enzyme, and trial evidence shows no additional benefit from exceeding 100mg.

What to expect

Most people notice an effect within thirty to sixty minutes, with concentration peaking near the one-hour mark, the same timeline at either strength. A high-fat meal slows absorption and can delay that peak by roughly an hour, so if precise timing matters to you, a lighter meal beforehand helps. Once active, the effect holds for about four to six hours at 50mg or 100mg. 100mg is generally reserved for people whose response to 50mg wasn't strong enough, and the documented side-effect pattern runs somewhat more pronounced at that dose: headache, mild indigestion, flushing, occasional blue-tinted vision, and nasal congestion, most of it transient.

Safety information

Sildenafil is absolutely contraindicated with nitrate medications; combining the two can trigger a severe, dangerous fall in blood pressure. Your provider will also want to know about certain medications and health history before confirming a prescription at either strength: alpha-blockers, CYP3A4-inhibiting drugs such as some antifungal or HIV treatments, uncontrolled blood pressure, a prior heart attack or stroke, cardiovascular disease more broadly, or a personal history of NAION, a rare condition affecting the optic nerve. Side effects run somewhat more pronounced at 100mg than at 50mg. If your provider decides sildenafil isn't clinically appropriate for you, you won't be charged for the medication.