A Member of the University of Maryland Medical System   |   In Partnership with the University of Maryland School of Medicine

Share

Email PageEmail Print PagePrint

Home > Medical Reference > Encyclopedia (English)

Toggle: English / Spanish

Drug allergies - Overview

Alternative Names

Allergic reaction - drug (medication); Drug hypersensitivity; Medication hypersensitivity

Definition of Drug allergies:

Drug allergies are a group of symptoms caused by an allergic reaction to a drug (medication).

Causes, incidence, and risk factors:

Adverse reactions to drugs are common, and almost any drug can cause an adverse reaction. Reactions range from irritating or mild side effects such as nausea and vomiting to life-threatening anaphylaxis.

A true drug allergy results from a series of chemical steps within the body that produce the allergic reaction to a medication.

It can develop two different ways:

  1. The first time you take the medicine, you have no problems, but your body's immune system produces a substance (antibody) called IgE against that drug. The next time you take the drug, the IgE tells your white blood cells to make a chemical called histamine, which causes your allergy symptoms.
  2. A drug allergy may also occur without your body producing IgE, but this is not well understood.

Most drug allergies cause minor skin rashes and hives. Serum sickness is a delayed type of drug allergy that occurs a week or more after exposure to a medication or vaccine.

Penicillin and related antibiotics are the most common cause of drug allergies. Other common allergy-causing drugs include:

  • Sulfa drugs
  • Anticonvulsants
  • Insulin preparations (particularly animal sources of insulin)
  • Iodinated (containing iodine) x-ray contrast dyes (these can cause allergy-like anaphylactoid reactions)

Most side effects of drugs are not due to an allergic reaction. For example, aspirin can cause nonallergic hives or trigger asthma. Some drug reactions are considered "idiosyncratic." This means the reaction is an unusual effect of the medication, not due to a predictable chemical effect of the drug. Many people confuse an uncomfortable, but not serious, side effect of a medicine (such as nausea) with a true drug allergy, which can be life threatening.

  • Reviewed last on: 6/29/2010
  • Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Paula J. Busse, MD, Assistant Professor of Medicine, Division of Clinical Immunology, Mount Sinai School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

References

Celik G, Pichler WJ, Adkinson NF Jr. Drug Allergy. In Adkinson NF Jr., , eds. Middleton's Allergy: Principles and Practice. 7th ed. Philadelphia, Pa; Mosby Elsevier; 2008: chap 68.

Grammer LC. Drug allergy. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 275.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
adam.com
 
Adam QualityA.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
adam.com
Connect with UMMC
Facebook Twitter YouTube Blog iPhone

Please rate the quality of this article.

Do you find this article to be helpful / informative?
              
Poor                                       Excellent

Do you have any brief comments on this page: (up to 255 characters)

© 2011 University of Maryland Medical Center (UMMC). All rights reserved.
UMMC is a member of the University of Maryland Medical System,
22 S. Greene Street, Baltimore, MD 21201. TDD: 1-800-735-2258 or 1.866.408.6885