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Drug Allergy

Drug Allergy Overview

Allergic reaction is an uncommon and unwanted side effect of medication.

Several different types of allergic reactions to medications can occur. Reactions to drugs range from a mild localized rash to serious effects on vital systems. The body's response can affect many organ systems, but the skin is the organ most frequently involved.

It is important to recognize the symptoms of a drug allergy, because they can be life-threatening. Death from an allergic reaction to a medication is extremely rare, however.

An allergic reaction does not often happen the first time you take a medication. A reaction is much more likely to occur the next time you take that medication. If you have a reaction the first time, you probably were exposed to the medication before without being aware of it.

Not all adverse reactions to drugs are allergies. In fact, fewer than 10% of adverse drug reactions are allergic. Other causes of adverse reactions are interactions between two or more drugs, inability to break the drug down completely in the body (as occurs with liver or kidney damage), overdose, and irritating side effects such as nausea, vomiting, or diarrhea. If you have experienced a nonallergic drug reaction, it is important to describe it as such to medical personnel-not as an allergy. If you don't know just describe the reaction the best way that you can.



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Drug Allergy

Allergic Reaction Overview

An allergic reaction is the body's way of responding to an "invader." When the body senses a foreign substance, called an antigen, the immune system is triggered. The immune system normally protects the body from harmful agents such as bacteria and toxins. Its overreaction to a harmless substance (an allergen) is called a hypersensitivity reaction, or an allergic, reaction.

  • Anything can be an allergen. Common dust, pollen, plants, medications, certain foods, insect venoms, animal dander, viruses, or bacteria are examples of allergens.
  • Reactions may occur in one spot, such as a small skin rash or itchy eyes, or all over, as in a whole body rash.
  • A reaction may include one or several symptoms.

In rare cases, an allergic reaction can be life-threatening (known as anaphylaxis). Each year in the United States, over 400 people die from anaphylactic reactions to penicillin, and ne...

Read the Allergic Reaction article »



Read What Your Physician is Reading on eMedicine

Drug Eruptions »

Drug eruptions can mimic a wide range of dermatoses. The morphologies are myriad and include morbilliform (most common, see Media file 1), urticarial, papulosquamous, pustular, and bullous. Medications can also cause pruritus and dysesthesia without an obvious eruption.

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