Marla Thank you for your question and welcome to ADHDCentral.com.   Adderall, and other stimulant medication, does not need to build up in the system to be effective. It is effective for between 3 and 12 hours after the medication is taken (depending on which medication) and then is done until the next dose. Some people choose to take medication only when needed and to skip days when it is not needed.   Some doctors believe children should not take medication during the summer months and others believe medication should be continued, as symptoms of ADHD do not just interfere with school but also interfere with home life, social relationships and more. Whether or not your child continues medication would depend on your situation.   You can read more about this:   ADHD Medication in the Summertime   I hope this information helps   Eileen