Prescriptions: Complying with the Doctor's Orders (cont.)

The Role of Medicines in Disease Prevention

Medicines are commonly used to prevent illnesses. For example, aspirin is used to prevent heart disease and stroke while folic acid is used to prevent birth defects. However, if these medications are not taken regularly according to the doctor's orders, they may not prevent the disease.

Other examples include:

  • Vaccinations in children and adults must be given at specifically designated times.

  • Persons traveling to countries with malaria must take medicines to prevent malaria beginning well in advance of arriving in the country (so that beneficial blood levels of the medicine are present right from the beginning of the trip). The anti-malarial medicines must be continued during and after the trip in order to fully protect from malaria.

  • Birth control pills must be taken regularly and in the proper sequence, when applicable, in order to prevent pregnancy.

Avoiding an Overdose and other Side Effects

Medications easily can become toxic or give rise to side effects if not taken as directed. Taking more than the recommended dose can greatly increase the risk of side effects with no additional benefit for the user. A perfect example is the common pain-reliever, acetaminophen (Tylenol), which in larger-than-recommended doses can cause serious liver damage but does not provide greater pain relief.

Side effects and/or an overdose also can occur when taking another person's medications since they often are prescribed based on an individual patient's age and weight (in addition to considerations such as allergy and underlying illnesses, as discussed previously).


The bottom line is that to obtain the maximum benefit from medicines and minimize the potential for side effects, patients must always follow exactly the doctor's instructions for taking a medicine and complete the full course of the medicine.

Reference: Harrison''s Principles on Internal Medicine, 14th edition, 2006

Last Editorial Review: 9/4/2009