It continues to work for up to 4 hours, although its action is usually less after 2 hours. Make sure you tell your doctor if you have any other medical problems, especially: Abnormal penis, including a curved penis or birth defects of the penis—Chance of problems occurring may be increased and this medicine should be used with caution in these patients. What should I do if I forget a dose? If you see air bubbles in the syringe, repeat the steps. Adults 65 years of age and older—25 mg as a single dose no more than once a day, 1 hour before sexual intercourse. John’s wort. Rarely reported side effects include: an erection that will not go away priapism.Viagra vs. over-the-counter products. Many over-the-counter (OTC) products may be advertised to help with ED. Examples of these products include: dehydroepiandrosterone (DHEA) ginseng;. Other options. There are several options to treat erectile dysfunction aside from oral medications like Cialis, including: erectile dysfunction pump, which can be a penis or vacuum pump. penile. Roman is a telehealth prescription service and online pharmacy that provides prescription Cialis for ED and a host of other conditions, like hair loss, cold sores, and premature ejaculation. When.