What is a drug allergy?
A drug allergy is an allergic reaction to a medication. When a drug first enters the body, it may trigger an inappropriate allergic immune response. The immune system creates specific IgE (or allergic) antibodies (proteins made by the immune system to fight specific antigens). The body becomes sensitized, and when the drug is taken again, the drug bonds to the IgE antibodies that activate immune cells to release chemicals and a variety of proteins. Adverse drug reactions can occur without the generation of allergic (IgE) antibodies. The exact mechanisms involved in triggering these reactions has not been determined.
What are the symptoms of drug allergy?
Symptoms can range from mild discomfort to life-threatening reactions. During allergic reactions histamines and other medicators are released by immune cells that cause a variety of symptoms which may include hives, skin rash, itchy skin or eyes, congestion and swelling in the mouth and throat. Symptoms for more severe reactions include difficulty breathing, blueness of the skin, dizziness, fainting, anxiety, confusion, rapid pulse, nausea, diarrhea and abdominal disturbances.
Which drugs most often cause an allergic reaction?
The most common cause of drug allergies is penicillin. Other antibiotics similar to penicillin also cause a large number of drug allergies. IgE-mediated allergic drug reactions can also occur to insulin,vaccines, and other therapeutics.
Other drugs commonly found to cause reactions which do not involve IgE antibodies (non-IgE mediated drug reactions) are sulfa drugs, barbiturates, anticonvulsants, local anesthetics such as Lidocaine and iodine (found in many X-ray contrast dyes).
How are drug allergies diagnosed?
Drug allergies are diagnosed by a careful review of the patient’s medical history and symptoms by an allergy & immunology specialist. If an allergy to an antibiotic such as penicillin is suspected, the allergist may do a skin test [link] to confirm the allergy. However, skin testing is not available for all drugs. If a patient has had a severe, life-threatening, allergic reaction to a particular drug and no diagnostic blood or skin tests exist, doctors will not consider that drug a viable treatment option.
How are drug allergies treated?
The primary concern when treating severe drug allergies is relieving the symptoms. Common symptoms such as rash, hives and itching can often be controlled with antihistamines and occasionally corticosteroids. For coughing and lung congestion bronchodilator inhalers may be prescribed. For more serious, anaphylactic symptoms (life-threatening reactions including difficulty breathing or loss of consciousness) epinephrine (adrenaline) is either inhaled or injected.
Desensitization is a procedure performed under the careful observation of an allergy & immunology specialist if the patient has a life-threatening infection and no other reasonable treatment exists. It may be used for penicillin allergy or allergy to any other antibiotic. This technique is designed for the immune system to temporarily tolerate a particular antibiotic. The targeted antibiotic is administered periodically at increasingly larger levels until the immune system learns to tolerate the drug.
Living with drug allergies
If you have a drug allergy, you should always inform your health care provider before undergoing any type of treatment, including dental care. It is also a good idea to either wear medic-alert jewelry or carry a card that identifies your drug allergy. In cases of emergency, it could save your life.
