What happens if I take too much ADHD medication, or I miss a dose? 

Edited

If you accidentally take too much medication, contact your nearest hospital or GP immediately.  
 
Missing a dose will have no adverse medical effect, although it is possible that your symptoms of ADHD will be more pronounced if you have not taken your medication.  

Whilst you should never double up on doses to make up for a missed one, you can take ADHD medication later than you usually would. But please be aware that stimulant medications can affect your ability to sleep, and therefore it is not recommended to take it too late in the day or you may be unable fall asleep until much later than usual.