Some medications should not be taken with sildenafil. Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient. What should I do if I forget a dose? Be sure to let your doctor and pharmacist know that you are taking these medications before you start taking sildenafil. Sexual activity may be a strain on your heart, especially if you have heart disease. Place the tip of the syringe into you or your child’s mouth and point it towards the cheek. Ask your healthcare professional how you should dispose of any medicine you do not use.Cost. Overdose. Ask your doctor. Q&A. Drug Images. What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a . Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in .  · Proper Use. Drug information provided by: Merative, Micromedex ®. Use sildenafil exactly as directed by your doctor. Do not use more of it and do not use it more .