Medication (also called medicine or pharmaceutical drugs) is the use of licenced drugs to treat or cure an illness. Some drugs are freely sold. They are called over the counter (OTC) drugs. Other drugs are so powerful or dangerous that a doctor must give permission to use the drug. The note from the doctor is called a "prescription." Some drugs are sold only when the purchaser shows a medical prescription to the seller of medicines. These drugs are called prescription only medicines (POM).