Any medicine like this should be taken only after a physician opinion. If the doctor so opines, then it can be taken with a frequency as decided. Normally it is a safe medicine
Health Tips
Serious Side Effects of Sildenafil which you should know are: Sudden vision changes, blurred vision, or vision loss. An erection that's painful or lasts longer than four hours. Symptoms of a heart attack, such as chest pain; chest pain that spreads to your jaw or shoulder; sweating; or nausea. Irregular heartbeat. Shortness of breath.