Take tadalafil exactly as directed. When choosing one, tell your doctor or other health care professional what your preferences are, such as cost, ease of use, how long the drug’s effects last and side effects. Your doctor may need to change the doses of your medications or monitor you carefully for side effects. If you are taking tadalafil for erectile dysfunction on a regular schedule, take the missed dose as soon as you remember it. Also tell your doctor if you or any of your family members have or have ever had an eye disease such as retinitis pigmentosa an inherited eye condition that causes loss of vision or if you have ever had sudden severe vision loss, especially if you were told that the vision loss was caused by a blockage of blood flow to the nerves that help you see.The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide. Industry Leaders · Watch Video · Fully Equipped · Custom Formulation. Generic tadalafil has been available since and has proven to be just as effective and safe as the brand name. The drug is available in low daily doses that keep the .