Sildenafil Gel pills are prescribed to treat erectile dysfunction. These tablets are an effective treatment for male sexual dysfunction or erection difficulties. This medication is administered 30 minutes or an hour before sexual activity. It has a duration of 3 to 4 hours. Sildenafil Gel should be taken with water. The tablet causes side effects such as headaches, fevers, and chest pains. These tablets are taken as directed by the doctor.