Erectile dysfunction can be caused by a variety of factors , including age, cardiovascular problems, diabetes, and other conditions that affect nerve function or blood flow. Your health information should remain between your provider and yourself. These drugs also have to be specially labeled, so many online pharmacy companies have already elected not to deliver them. This is important for your overall health and safety, as certain medications can negatively interact with each other or cause existing conditions to worsen. Some services offer a subscription option where they’ll send your medications every month at a discount.Depending on your symptoms and needs, you may be prescribed Viagra, sildenafil, Cialis, tadalafil, Stendra, paroxetine, or a combination of tadalafil and sildenafil, available as . When you buy from an unknown company, you run the risk of getting counterfeit medicines. By some estimates, more than half of all ED drugs sold online are fakes. Some of these . These lists contain up to 10 of the most common mild side effects that can occur with Viagra, with Cialis, or with both drugs (when taken individually). Can occur with Viagra: .