A side effect is an unexpected symptom that occurs during treatment with a drug. Prescription drugs, Over-The-Counter (OTC) drugs or herbal supplements taken for either preventing or treating a condition may result in unwanted side effects that can be harmful to the body. These side effects can be mild, moderate or severe.
Complications from side effects may require immediate medical attention. Severe side effect of a drug can cause damage to vital organs, lead to birth defects and even result in death.
Very useful calculator
Good Information