Medications work by modifying specific physiological functions within the body. In addition to the curative effects the drug may bring about, potential adverse reactions may also occur. Unintended and negative reactions to drugs are among the leading causes of death in many countries, reports the World Health Organization. Adverse drug reactions can take various forms, and understanding the more common adverse effects will help patients cope with any unexpected reaction to a prescribed drug.
Predictable Reactions
Predictable drug effects are the more common types of adverse drug reactions, notes American Family Physician. These reactions have been studied by the drug companies and have been associated with taking the drug. These reactions are usually dose related. Physicians can usually anticipate these reactions once the dosage amount is known. Most listed side effects of a drug are considered predictable adverse drug reactions. Examples of these include a dry mouth from antihistamines and a cough from ACE inhibitors. If a specific drug is taken in excess, the doctor can predict the possible adverse effects. For example, a commonly seen reaction is seizures after a patient takes or is given an overdose of lidocaine.
Allergic Reactions
Allergic responses to an ingested drug account for 10 percent of all adverse drug reactions, according to the American Academy of Allergy Asthma and Immunology. When the immune system is activated, it attacks the drug, and this can cause damage to the patient. Examples of immunological adverse drug reactions include an allergic response to penicillin, contact dermatitis from an antihistamine and drug-induced lupus. Allergic reactions can range from mild to life threatening. If the allergic response is intolerable, the patient should be prescribed another, less harmful medication.
Intolerance
Certain individuals are unable to tolerate certain drugs, reports American Family Physician. These patients, for genetic or physiological reasons, cannot take certain drugs without developing severe, unexpected side effects. An example of intolerance to a drug is tinnitus, or a ringing sensation in one or both ears, after taking even small doses of aspirin.
Drug-Drug Interactions
Adverse drug reactions occur when two types of drugs interact within the patient's system and produce deleterious and unanticipated reactions. This is called an adverse drug-drug interaction, reports the U.S. Food and Drug Administration. For example, combining sedatives, which are drugs to help patients sleep, with an anti-allergy medication, such as an antihistamine, can slow reaction time and make driving or operating machinery significantly more dangerous.
References
- World Health Organization: Medicines: Safety of Medicines-- Adverse Drug Reactions
- American Family Physician: Adverse Drug Reactions: Types and Treatment Options
- American Academy of Allergy Astma and Immunology: Tips to Remember: Medications and Drug Allergic Reactions
- U.S. Food and Drug Administration: Drug Interactions: What You Should Know
