Order Online and pickup at your local Costco. Find an expanded product selection for all types of businesses, from professional offices to food service operations. Our Costco .If you experience chest pain, dizziness, or nausea during sexual activity, call your doctor immediately and avoid sexual activity until your doctor tells you otherwise. Using this medicine with any of the following may cause an increased risk of certain side effects but may be unavoidable in some cases. The amount of medicine that you take depends on the strength of the medicine. What side effects can this medication cause? If you are taking sildenafil to treat erectile dysfunction, follow your doctor’s directions and the guidelines in this paragraph.This means that 4 hours after you take a dose, your body has cleared half of the dose. In most cases, it takes about 5 half-lives for your body to completely remove a drug from your system. So. Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung drug is more popular than comparable drugs. It is available in generic and brand versions. Generic sildenafil is covered by most Medicare and insurance plans, but .  · 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.Use only the brand of this medicine that your doctor prescribed. Tell your doctor if sildenafil is not working well or if you are experiencing side effects. The following nonprescription or herbal products may interact with sildenafil: cimetidine Tagamet HB , St. For treatment of erectile dysfunction: For oral dosage form tablets : Adults up to 65 years of age—50 milligrams mg as a single dose no more than once a day, 1 hour before sexual intercourse. Tadalafil Cialis.