If you have a pre-existing heart condition or high blood pressure, Ritalin is probably not the best idea. It is known to increase heart palpitations, create irregular rhythms and raise blood pressure. While the FDA says that the jury is still out regarding Ritalin heart attack death, the fact remains that it is a stimulant drug and will have the same side effects as other stimulants (mentioned above). Especially given your age I would check with your doctor regarding other possible medications to treat your ADD. There are non-stimulant medications that would have less potential negative side effects.