Rex MD offers a variety of prescription treatment options for ED. Our most popular offerings include sildenafil (generic Viagra), which is taken 30 to 60 minutes before sexual activity, and tadalafil (generic Cialis), which is taken daily. Complete our free online consultation to learn which option is right for you. After completing your consultation, you’ll have the option to select your prescription preference at checkout. However, if you need to change your medication or dosage, a Rex MD physician can help you make that transition at any time.