Sildenafil is known as generic Viagra because it is not sold under the Viagra brand name. People take it in a dosage of 25, 50, or 100 milligrams (mg) per day. Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor - the standard treatment for erectile dysfunction.

Viagra is the brand name for a medicine known as sildenafil which has been proven to be effective for the treatment of erectile dysfunction. The generic drug contains the same active ingredient as the branded drug, in this case sildenafil citrate, and is therapeutically equivalent to the branded medicine Viagra.

Viagra (sildenafil) is a prescription medication used to treat erectile dysfunction. Headache, flushing, and upset stomach are common Viagra side effects. These effects are usually mild and often resolve on their own. While rare, Viagra can cause an erection that lasts longer than 4 hours (priapism).

On average, Viagra lasts between 2 and 3 hours before its effects start to diminish. Viagra can last up to 5 hours or longer depending on your dosage, your body's metabolism, and other external factors.

The usual dose is 50mg, when you need it. Do not take it more than once a day. The dose can be increased to 100mg or decreased to 25mg depending on its effect. Take sildenafil up to 4 hours before you want to have sex.

While generic sildenafil and Viagra are equally safe and effective, the medications have one key difference: price.

Both Viagra and the non-branded generic version, Sildenafil, are safe to take everyday, both in their 50mg and 100mg dosages. However, you really shouldn't be taking them daily if you are not intending to engage in sexual activity daily.

Viagra typically starts working within 30 to 60 minutes and lasts for about 2 to 3 hours after that. Seek medical attention if you experience an erection lasting longer than 4 hours.

Regardless of your dose or individual metabolism rate, Viagra usually wears off after 4-6 hours. Note that your erection should never last more than four hours. If it does, seek medical treatment.

The effects of Viagra can last 4 to 8 hours, depending on the individual person and the dose you take. In fact, some people may experience more than one erection during this time. However, just because Viagra can stay in your body for up to 8 hours doesn't mean your erection should last that long.

Dosage and strength for erectile dysfunction The usual dose is 50mg, when you need it. Do not take it more than once a day. The dose can be increased to 100mg or decreased to 25mg depending on its effect. Take sildenafil up to 4 hours before you want to have sex.

Viagra will remain in your system for around 24 hours, although Viagra effects are less pronounced after around 4-5 hours.