Ask your pharmacist for a list of the ingredients. Some medications should not be taken with sildenafil. Sexual activity may be a strain on your heart, especially if you have heart disease. Follow the manufacturer’s directions to use and clean the oral syringe. If you are taking sildenafil for erectile dysfunction, you are unlikely to miss a dose since this medication is taken as needed, not on a regular dosing schedule. Continue to take sildenafil even if you feel well. Take sildenafil exactly as directed.Sildenafil, also known as generic Viagra, is the primary ingredient used in Viagra and works to treat ED symptoms in the same way. While brand name Viagra is slightly different than sildenafil.  · Viagra comes as an oral tablet that contains the active drug sildenafil. Sildenafil is also available in generic form. Viagra is classified as a phosphodiesterase type 5 (PDE5) inhibitor. For Erectile Dysfunction “I have been taking Viagra for about 15 years. It works great for me with minimal side effects. One 50 mg tablet turns me into a raging bull for about 18 hours. The key is to always take it on an empty stomach. I discovered that if my body is low in salt, the Viagra does not work as well.