The products discussed in this site may have different product labeling in different countries. 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. The four main medicines taken by mouth for erectile dysfunction are: Avanafil Stendra. Some people may also have ringing in their ears tinnitus or dizziness. Vardenafil usually works for 4 to 5 hours.16 tablets. £ / month. £ One-time or subscription. Viagra for men, often referred to as the ‘blue pill’, is an ED pill which can help to improve sexual wellbeing by enhancing erectile performance. It works by increasing blood . Cialis lasts up to 36 hours in the body, while Viagra lasts 4–6 hours in the body. Both are taken 30 minutes before sex. Cialis can cause limb pain, while Viagra can cause vision change, rash. 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.