Children should be screened for heart problems with an electrocardiogram before taking drugs such as Ritalin to treat hyperactivity and attention-deficit disorder according to the American Heart Association. Children already on the drugs should also be tested.

Stimulants can increase blood pressure and heart rate which for most children isn’t a problem. But for those with heart conditions, it could make them more vulnerable to sudden cardiac arrest – an erratic heartbeat that causes the organ to stop pumping blood through the body – and other heart problems.

About 2.5 million children and 1.5 million adults in America take some form of medication for attention-deficit (hyperactivity) disorder, or ADHD, according to government estimates.