<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have been having trouble with maintaining an erection during sex.  <response>: Based on your symptoms, I recommend that you take medications such as Sildenafil Viagra, Tadalafil Cialis, Vardenafil Levitra, Alprostadil Muse, and Papaverine to treat your condition. Additionally, Tamsulosin Flomax, Dutasteride Avodart, Alfuzosin Uroxatral, Colestipol, Phentolamine or Testosterone may be prescribed depending on the underlying cause. 