There are many potential causes of ED, and some are easier to treat than others, however, there is not likely to be a cure given the most common causes of ED. For instance, if the ED is caused by age-related blood flow issues, these are not likely to spontaneously recover, thus, there is no viable cure even if some medicine(s) can treat the symptom. If the ED is due to testosterone deficiency, then taking testosterone may improve erections but it likely cannot cure the issue as you would need to continue taking testosterone in order to address those symptoms. The likelihood of a complete cure once this condition has set it is low. Of course the younger the patient the higher chance that treatment will be successful.