It can significantly raise blood pressure and pulse in someone who already has high blood pressure or heart problems. Ritalin is safe to take with antibiotics as well as cold medicines, but in someone with high blood pressure, thyroid problems or heart disease, they should consult with their primary care provider first. Antihistamines, commonly found in many cold medicines, can decrease the effectiveness of stimulant medicines such as Ritalin when they are taken together. When Ritalin is taken with food, less of it is absorbed. It is best taken on an empty stomach.
Caffeinated drinks can increase the effects of stimulant medicines, so it is best to avoid caffeine.
Alcohol can decrease the effectiveness of Ritalin. Other drugs that have a potential to interact with Ritalin include seizure medicines, blood pressure medicines, blood thinners, and antidepressants. This does not mean that they can't be used together. Their concurrent use requires close follow-up at frequent intervals with the health care provider to ensure their effectiveness and safety.