Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. Use the oral syringe provided with your medication to measure and take your dose. Children—Use is not recommended. John’s wort. Do not mix the liquid with other medications or add anything to flavor the medication. · Description and Brand Names. Drug information provided by: Merative, Micromedex ®. US Brand Name. Revatio. Viagra. Descriptions. Sildenafil is used to . Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial . Viagra basics. The active drug in Viagra is sildenafil. It belongs to a group of drugs called phosphodiesterase-5 inhibitors. Viagra comes as tablets you take by .