Ruth,
Taking a child off medication on weekends and during the school holidays is a personal decision.
There are two different thought processes in this decision. The first is that a break from medication will allow the child to catch up in growth, however, there is little evidence to back this up.
The second is that taking a child off medication may do them more harm than good. The constant changing of taking medication and not taking medication can be difficult to adjust to. In addition, ADHD is not just a school day disorder. It impacts many different aspects of a person's life, including social and family life. Medication can help in decreasing symptoms during the school day but can also help decrease distractibility and inattention during the weekend to listen to instructions given by parents. In addition, medication helps to decrease impulsiveness.
This may be something that you would need to discuss with your physician. If your doctor has recommended weekends off from medication, talk about the problems you are experiencing. You should never change medication use without first discussing it with your doctor.
I hope this helps.
Eileen