Medications can play three different roles :
To prevent a disease
Certain medications will prevent you from contracting a disease. Vaccines and serums for example enable your body to produce immune defenses against the disease. Some of these vaccines are used worldwide to protect oneself against serious diseases such as the measles and tuberculosis.
Others are only used in areas where the risk of contracting the disease is high. This is the case for the vaccines against yellow fever, cholera, typhoid fever, meningitis or viral hepatitis.
To relieve the pain or ease discomfort
When you are sick you sometimes have a headache or a pain in the stomach, and you may feel too hot or too cold. These signs are symptoms of a disease. The medical staff can prescribe you medication to relieve the pain or or ease discomfort
To cure a disease
In order to treat certain diseases the medical staff may choose to give you a specific type of medication such as antibiotics that enable to destroy the small cells responsible for the disease : bacteria.