The concomitant use of erythromycin or strong CYP3A4 inhibitors e. L-Arginine L-Arginine is an amino acid that is usually found in fish, red meat, and dairy products. The effectiveness of these infusions has never been studied. One product may work well for one person, but may not provide the desired results for another. The mean times adjusted for baseline to onset of limiting angina were  · Specifically, you may have a lower starting dosage than usual if you’re over age For example, a year-old might start at a dose of 50 milligrams (mg), while a year-old might have a. Tell your healthcare provider about all the medicines you take 1, including prescription and over-the-counter medicines, vitamins, and herbal supplements. VIAGRA may affect the way other medicines work, and other medicines may affect the way VIAGRA works causing side effects. Especially tell your healthcare provider if you take any of the. Viagra (sildenafil) is a prescription drug that’s used to treat erectile dysfunction (ED). The drug comes as a tablet you’ll take by swallowing. It’s usually taken as needed about 1 hour.