If chest pains, dizziness, or nausea are experienced during sex, the exertion should be stopped and your doctor informed. It affects the way the medicine works. Children: Viagra Sildenafil is not intended for use by children or adolescents under 18 years of age. Do not mix the liquid with other medications or add anything to flavor the medication. Medications other than the ones listed above may interact with Viagra Sildenafil.Rarely reported side effects include: an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis. sudden vision loss in one or both eyes. 1 day ago · In addition to Viagra, REX MD also offers brand-name Cialis and generic Cialis (tadalafil). Both Viagra and sildenafil are available in mg, mg, and mg doses. AdED treatments prescribed online and delivered to your door. Health Canada authorized. Free & discreet 2 day shipping. Get started now with a quick online visit.