What Is an Adverse Event?

Sometimes it’s hard to pinpoint the actual cause of an adverse drug event (ADE) because a drug allergy, a drug reaction or a medicine error can all be culprits. Medication errors, mishaps that occur during the prescribing, transcribing or administering a drug, are more common than an adverse drug event. The VA Center for Medication Safety reports about 25% of adverse drug events are due to medication errors. Here we explain the differences, so you and your doctor can better diagnosis the problem and know where responsibility lies.

When ADE Involves the Immune System


A drug allergy occurs when your immune system mistakenly identifies a drug as a harmful substance instead of a helpful remedy. Your immune system then reacts to the medication. Chemicals released by this reaction cause the signs and symptoms associated with an allergic reaction.

When ADE Doesn’t Involve the Immune System


Drug allergies and non-allergic drug reactions are often confused because they can cause similar symptoms when one is undergoing an adverse drug event. Some allergic and non-allergic drug reactions can be severe or life-threatening (and occur when the drug is taken at normal doses under normal conditions—and also occur in the form of an overdose).

Although one’s adverse drug reactions may seem like a drug allergy, they could be associated with a drug side effect or signs of a drug sensitivity — not an allergic reaction. Some examples of drugs that commonly cause non-allergic adverse drug reactions
  • X-ray contrast. Some people are sensitive to intravenous (IV) contrast used in some X-ray tests. This adverse drug reaction can cause itching, flushing and a drop in blood pressure.
  • Aspirin and other pain relivers. In some people, aspirin, ibuprofen (Advil, Motrin, others), naproxen (Aleve, Naprosyn, others) and others, can cause breathing trouble, wheezing and hives.
  • Antibiotics. Some antibiotics often cause reactions such as stomach ache or diarrhea.
  • High blood pressure medication. Angiotensin-converting enzyme (ACE) inhibitors sometimes cause coughing and swelling of the lips, tongue and face.
If you have an unexpected adverse drug reaction, the steps that your doctor may take to diagnose the source of the problem include:
  • A physical examination. In addition to a physical exam, your doctor will have a number of questions. For example, he or she might ask how long after you took the medication did you experience an adverse drug reaction?
  • Blood tests. A blood sample can only be used to detect an allergy to a few drugs, such as certain antibiotics, muscle relaxants and insulin. Blood tests are helpful when someone has had an adverse drug event in the past and can’t risk another such reaction.
  • Skin tests. For some drugs, including certain antibiotics, an allergy skin test may be used to determine whether you're allergic. A small amount of the drug is injected into the skin of your forearm or back. If you're allergic to the drug being tested, you develop a red, raised bump or other adverse drug reaction.
  • Drug provocation tests. During drug provocation testing, gradually increasing doses of the offending drug are given. The drug can be given in different ways for the test, including orally or under the skin. A reaction indicates a possible allergy or sensitivity to the drug. This test is usually used only when an alternative drug won't work as well or isn't an option. It may also be used when skin and blood tests aren't conclusive. Generally, only specialized allergy centers perform provocation tests for a drug allergy because anaphylaxis can be a possible adverse drug reaction.
A number of drugs can cause a drug allergy, including prescription and over-the-counter medications. If you or your loved one’s health has been compromised due to a third-party, contact Seeger Weiss for advice.

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