My adult son takes 90 mg of vyvanse (lisdexamfetamine)?

Dr. Prescription. 90 mg is a relatively high dose of vyvanse (lisdexamfetamine). If your son's doctor has prescribed that dose of vyvanse (lisdexamfetamine), is monitoring his response and he is not having any side effects, you should get assurance by talking to your pediatrician.
Vyvanse (lisdexamfetamine) The question is, is it working correctly for him and not causing side effects. If so then encourage him to live healthy lifestyle and follow up with his doctor, afterall that's what a good dad does.