Sildenafil usually should not be taken more than once every 24 hours. 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. However, the dosage can range from 25— mg. Viagra is not for use by females. Your healthcare provider can help you determine the right dosage for you.Sildenafil citrate is a white to off-white crystalline powder with a solubility of mg/mL in water and a molecular weight of VIAGRA is formulated as blue, film-coated rounded-diamond-shaped tablets equivalent to 25 mg, 50 mg and mg of sildenafil for oral administration. Answer 1 of I use generic viagra which i order online for personal use as it is much cheaper than buying from the Doctor. I am heading there in 2 weeks and want to take .  · You can get the branded Pfizer pills for roughly ฿ per pill (these are usually the mg and will blow your cock off) or the off-brand stuff for roughly ฿ for a box of four, both have the same active ingredient though (sildenafil). Or so a mate has told me anyway. AdrianRad74 • 2 yr. ago.