It is especially important to talk to your doctor or pharmacist if you are taking any of the following: • Medicines that work on your brain to help you calm down (benzodiazepines), or some medicines for pain (opiates), medicines for allergy (some antihistamines), as Risperidone may increase the sedative effect of all of these. • Medicines that may change the electrical activity of your heart, such as medicines for malaria, heart rhythm problems (such as quinidine), allergies (anti-histamines), some antidepressants or other medicines for mental problems • Medicines that cause a slow heart beat • Medicines that cause low blood potassium (e. g. certain diuretics) • Medicines for Parkinson's disease (such as levodopa) • Medicines to treat elevated blood pressure.