Storage Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. At the same time, on-treatment function was better in treated patients who were less impaired at baseline. Urgent care clinics also accept most insurance plans, which provides flexible, and affordable prescriptions. The dose can be increased to mg or decreased to 25mg depending on its effect. Often, these are prescribed for chest pain called angina.Sildenafil tablets for erectile dysfunction come in different strengths ranging from 25mg to mg. The usual dose is 50mg, when you need it. Do not take it more than once a day. The dose can be increased to mg or decreased to 25mg depending on its effect. Take sildenafil up to 4 hours before you want to have sex. Examples of Viagra’s more commonly reported side effects include: headache. flushing (temporary warmth, redness, or deepening of skin color) stuffy nose. indigestion (upset stomach) mild vision.  · The effects may be increased because of slower removal of the medicine from the body. Leukemia (blood related cancer) or. Multiple myeloma (blood related cancer) or. Sickle-cell anemia (blood disorder)—Sildenafil should be used with caution in these patients as problems with prolonged erection of the penis may occur.