An Allergic Reaction to Drug Can Occur Anytime

Amazingly, a person can have an allergic reaction to a drug anytime they take it, even if it caused no reaction in the past. A drug allergy occurs when one’s immune system reacts abnormally to a medication. It isn’t clear why some people develop drug allergies while others don’t. Inherited traits may play a role, along with environmental factors and taking a number of medications over time.

Most Typical Reactions


Many allergic reactions or adverse drug events start within minutes of taking a drug mediated by an immune response (e.g., hives, itching, fever, facial swelling, and shortness of breath). However, it's possible to develop an allergic reaction to a medication after you've been on it for up to several weeks.

Penicillin, which is widely prescribed for bacterial infections, is a good example. The drug allergy creates an overreaction by one’s immune system and may range from a mild rash to a life-threatening anaphylaxis episode. An anaphylaxis episode is a severe, potentially life-threatening allergic reaction.

The flood of chemicals released by your immune system during anaphylaxis can cause a person to go into shock; their blood pressure drops suddenly and their airways narrow, blocking normal breathing. Signs and symptoms of anaphylaxis include a rapid, weak pulse, a skin rash, and nausea and vomiting. Common triggers of anaphylaxis include certain foods, some medications, insect venom and latex.

Note that an allergic reaction that goes into anaphylaxis requires an immediate trip to the emergency department and an injection of epinephrine. If anaphylaxis isn't treated right away, it can lead to unconsciousness or even death.

Who’s most susceptible to an allergic reaction to drugs
While anyone can have an allergic or non-allergic reaction to a drug, the Mayo Clinic says that the following factors can increase one’s risk:
  • Having a past allergic reaction to the same drug or another drug. Even if past allergic reactions have been mild, you may still be at risk of a more severe reaction.
  • Taking a similar drug to one that caused an allergic reaction in the past. For example, if you've had a reaction to penicillin, you may also be sensitive to some other antibiotics.
  • Having a weakened immune system from conditions such as the Epstein-Barr virus or HIV/AIDS.
  • Having a history of other allergies, such as hay fever.
  • Taking several drugs at the same time, or taking frequent doses of the same medication.

Prevention


If you have a history of a possible drug allergy, a skin test may help find out for certain. Tests for a penicillin allergy are generally more reliable than are skin tests for other drug allergies.

Once you know you have a drug allergy, you'll need to avoid that drug and related drugs. Tell all of your health care providers, including your dentist, about your drug allergy. In case you're in an accident, you may want to wear a medical alert ID bracelet so that emergency workers will know about your drug allergy. In addition, you may want to carry a portable epinephrine injection (EpiPen, EpiPen Jr, Twinject) with you.

If you have been a victim of a drug allergy due to the negligence of another, contact Seeger Weiss.

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