Severe liver disease. To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and site usage information with other information we have about you. They have the same benefits and risks as their brand-name counterparts. These medicines are called PDE5 inhibitors. This medicine also works best when you take it an hour before sex on an empty stomach. Follow your doctor’s orders or the directions on the label. In some cases, online ED providers accept health insurance.This means that 4 hours after you take a dose, your body has cleared half of the dose. In most cases, it takes about 5 half-lives for your body to completely remove a drug from your system. So. Rarely, certain side effects like abnormal heartbeat, heart attack, stroke, bleeding in the lungs, and very bad high blood pressure have happened with this medicine (sildenafil tablets). Sometimes, this has been deadly. Most of the time, these problems happened in people who had heart problems before taking this medicine (sildenafil tablets). Cialis is only available by prescription in the United States. Viagra: Additionally, a study from Trusted Source. found that combining L-arginine and sildenafil (Viagra) worked better for.