Ask your healthcare professional how you should dispose of any medicine you do not use. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Kidney disease, severe or Liver disease, severe—Use with caution. 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. This category includes any drugs failing to meet FDA safety and effectiveness standards. Children—Use is not recommended. However, if you have medications that are considered a controlled substance including some cough medicines, tranquilizers, sleeping pills, antidepressants, or stimulants, you may only bring up to 50 dosage units across the border without a prescription.Last updated on Uses Warnings Before taking Dosage Side effects Interactions FAQ What is Viagra? Viagra relaxes muscles found in the walls of blood . Generic Viagra (sildenafil) is an alternative to the branded Viagra drug that can be used for treating erectile dysfunction (ED). It’s now sold by many manufacturers, including online. To make sure sildenafil is safe for you, tell your doctor if you have ever had: heart problems (chest pain, a heart rhythm disorder, heart attack); high or low blood pressure; blood .