- For most, sildenafil does exactly what it's supposed to and causes no notable side effects. However, it's not appropriate for all men who have erectile dysfunction. Sildenafil can cause serious health problems if it is taken with nitrate drugs, which are commonly prescribed for chest pain (angina). It is also more likely to cause problems in men who are taking protease inhibitors or alpha blockers, have kidney or liver problems, or are older than 65. These patients may be limited to a lower dosage and should carefully monitor how they react to the drug.
- Sildenafil is available in dosages of 25mg, 50mg and 100mg. The most common starting dose is 50mg, but men who are at increased risk of serious side effects may be limited to 25mg. The drug should be taken about one hour before its effects are desired, and it should not be taken more than once every 24 hours.
- The most common side effects associated with sildenafil include facial flushing, headache and sour stomach. Some men also experience vision changes such as increased sensitivity to light, blurred or blue-tinted vision. These side effects usually go away within a few hours, but they may recur each time you take sildenafil.
- Rarely, drugs in the same class as sildenafil have been associated with sudden hearing or vision loss. It is not known whether the drug itself, other factors or some combination causes this to occur. If you do experience vision or hearing loss while taking sildenafil, seek help immediately. Sildenafil may also cause priapism, which is when an erection does not go away. After several hours, priapism can cause severe damage to the penis. Call your doctor if you have an erection for more than four hours.
- Aside from erectile dysfunction, sildenafil is sometimes used to treat other conditions. It may be prescribed to women with sexual dysfunction, though there's little evidence to support its use for this purpose. It can also be prescribed to offset the libido-decreasing effects of SSRI anti-depressants. One study published in the New England Journal of Medicine indicates that sildenafil may also be useful in treating at least one non-sexual condition: pulmonary arterial hypertension.
