Dear service user, Thank you for writing to healthcaremagic. I understand your concerns. Vyvanse contains lisdexamfetamine and it is used to treat ADHD. The chance of erectile dysfunction as side effect with this medicine is very low (less than 2%). Let me know the duration of erectile dysfunction (ED) in your case. Cause of erectile dysfunction should be ruled out for proper treatment. Mostly it is due to stress and anxiety. There are several common causes of ED. 1. Diabetes (nerve damage and vessels narrowing) 2. Some medicines like anti depressants and anti psychotics 3. Performance anxiety (the most common reason) 4. Psychiatric disorders (depression, anxiety) 5. Alcohol use (nerve damage and testicular injury) 6. Smoking (vessels narrowing) 7. after some surgical procedures (nerve damage) 8. Low hormonal levels (rare) Let me know whether you achieve and maintain a good quality of erection in sleep, in the early morning, during masturbation but not at the time of coitus? If you are able to achieve and maintain erection in any one of the above mentioned situations than your problem is more likely psychological rather than physical. I recommend you to discuss this problem with your psychiatrist. He will assist you to find out reason for this problem in your case. Wish you good health.