There are 3 doses of Viagra: 25 mg, 50 mg and 100 mg. These side effects, although less common than not, are more likely to occur when you use a higher dose of this treatment, but are generally mild and go into no more than a couple of hours. We recommend that you use your lower 25mg dose of this treatment, if you have not yet used this treatment as this will help reduce drastically the risk of side effects. However, if this dose not have the desired effects, you can upgrade to 50mg or version of Viagra, or the highest available dose of 100mg. For most patients, the recommended dose is 50 mg taken, as necessary, about 1 hour before sexual activity. Based on safety and efficacy, the dose can be increased to a maximum recommended dose of 100 mg or decreased to 25 mg. Since higher plasma levels may increase both the effectiveness and incidence of adverse events, a starting dose of 25 mg should be considered in these patients. ) Based on the pharmacokinetic data, we recommend not to exceed a maximum single dose of 25 mg of VIAGRA in a period of 48 hours. VIAGRA is when co-administered with alpha-blockers, patients should be stable to alpha-blockers before starting treatment and VIAGRA VIAGRA should be initiated at the lowest dose (see drug interactions). In fixed dose studies, the incidence of certain adverse events increased with the dose. The nature of adverse events flexible doses studies, which reflect more closely the recommended dosage regimen was similar to that for fixed-dose studies. VIAGRA when it was taken as recommended (as on a necessary basis) in doses flexible, placebo-controlled clinical trials, the following adverse events were reported: Table 2. In fixed dose studies, dyspepsia (17%) and abnormal vision (11%) were more common to 100 mg compared with lower doses. At doses above the recommended dose range, adverse events were similar to those mentioned above, but generally were reported more frequently. When a single dose of 100 mg of VIAGRA was administered with erythromycin, a specific inhibitor of CYP3A4, steady state (500 mg bid for 5 days), there was a 182% increase in sildenafil systemic exposure (AUC). In addition, a study conducted in healthy male volunteers, administration of an HIV protease inhibitor saquinavir, an inhibitor of CYP3A4, steady state (1200 mg tid) with VIAGRA (100 mg single dose) resulted in an increase of 140% in C max sildenafil and a 210% increase in AUC of sildenafil. In another study in healthy male volunteers, co-administration with HIV protease inhibitor ritonavir, which is very powerful inhibitor P450, steady state (500 mg bid), with VIAGRA (100 mg single dose) resulted in a 300% (4 times) increase in C max of sildenafil and a 1000% (11 times) increase in plasma AUC of sildenafil