Sad face. In clinical trials, researchers found that 82 percent of men with ED reported some improvements in erectile function after using sildenafil at a dosage of mg. Start visit. Also tell your doctor if you have or have ever had pulmonary veno-occlusive disease PVOD; blockage of veins in the lungs ; a stomach ulcer; heart, kidney, or liver disease; a heart attack; heart failure; angina chest pain ; an irregular heartbeat; a stroke; chest pain; high or low blood pressure; high cholesterol; a bleeding disorder; blood circulation problems; blood cell problems such as sickle cell anemia a disease of the red blood cells , multiple myeloma cancer of the plasma cells , or leukemia cancer of the white blood cells ; conditions affecting the shape of the penis e. While study participants showed some improvement on the initial dose of sildenafil, the quality of their erections and general level of sexual satisfaction went up more significantly after using mg of sildenafil. Your healthcare provider may also start treatment for erectile dysfunction with this dosage if you have severe symptoms.Viagra (sildenafil) is a prescription drug that’s used to treat erectile dysfunction (ED). The drug comes as a tablet you’ll take by swallowing. It’s usually taken as needed about 1 hour.  · a light-headed feeling, like you might pass out. Common sildenafil side effects may include: flushing (warmth, redness, or tingly feeling); headache, dizziness; heartburn, nausea, or upset stomach. abnormal vision (blurred vision, changes in color vision) runny or stuffy nose, nosebleeds; sleep problems (insomnia); or. AdWith RexMD you’re saving time and money with our Viagra delivery. Get started now. Reliable E.D. meds prescribed by real doctors. Get your free & private online visit todayFree Shipping · Real Doctors · Discreet Packaging · Personalized PlanTypes: Premature Ejaculation · Privacy Policy · Sexual Health.