Drug Allergy: Symptoms, Causes, Diagnosis, Treatment & Prevention

 

A drug allergy is the immune system's response to a medication. A drug allergy can be brought on by any medication, whether it is prescription, over-the-counter, or herbal. However, several medications increase the risk of a drug allergy.

Fever, rash, and hives are  typical signs of a medication allergy. However, a medication allergy might potentially result in severe side effects. Among these is anaphylaxis, a severe and perhaps life-threatening condition.

A medication side effect and a drug allergy are not the same thing. An adverse reaction to a medication is known as a side effect. Medications' labels list their side effects. Drug toxicity is not the same as a drug allergy. When a person takes too much medication, they get drug toxicity.

An allergic reaction to a typically harmless substance in a prescription is known as a drug allergy. NSAIDs, sulfa medications, and penicillin are common causes. From minor discomfort to possibly life-threatening conditions, symptoms can vary widely. Avoiding drugs is the best strategy to treat a medication allergy. To assist in managing the symptoms of a drug allergy, you might require other medications.

What are drug allergies?

An allergic response to a medication is known as a drug allergy. It occurs when your body's defenses against drugs respond. One of the ingredients in the drug causes your body to become sensitive to it, and it "remembers" it as a dangerous foreign invader, similar to germs or viruses. Your immune system produces antibodies to eliminate the medicine from your body the next time you take it.

Allergies to drugs can be deadly. You must take immediate action if you or a loved one exhibits serious signs of a medication allergy, such as swelling of the tongue or neck, difficulty breathing, a rapid heartbeat, dizziness, or unconsciousness.

What is an example of a drug allergy such as?

An allergic reaction can occur from any medication. However, the following drugs are the most frequently known to trigger an allergic reaction:

• Penicillin is one type of antibiotic.

• Antibiotics that contain sulfonamides are known as sulfa drugs.

• Aspirin (Bayer®), naproxen (Aleve®), and ibuprofen (Advil®) are examples of nonsteroidal anti-inflammatory medications (NSAIDs).

• Tylenol® contains acetaminophen.

• Opiates, such as codeine and morphine.

• Medications used in chemotherapy.

• Drugs that prevent seizures.

• Some X-rays use dye, a contrast agent, to provide a sharper image.

Symptoms:

Serious drug allergy symptoms typically appear an hour after taking a medication. Hours, days, or weeks may pass before further responses occur, including rashes.

Symptoms of a drug allergy can include:

• Skin rash.

• Hives.

• Itching.

• Fever.

• Swelling.

• Breathlessness.

• Wheezing.

• Runny nose.

• Watery, itchy eyes.

The anaphylactic reaction

A rare and sometimes fatal medication allergic reaction, anaphylaxis alters the way many bodily systems work. Anaphylaxis symptoms include:

• Breathing difficulties brought on by constriction of the throat and airways.

• Cramps in the abdomen or nausea.

• Diarrhea or vomiting.

• Lightheadedness or dizziness.

• Fast, weak pulse.

• A drop in blood pressure.

• Seizure.

• Unconsciousness.

Additional ailments brought on by a medication allergy

Less frequent drug allergy reactions occur days or weeks after a medication is taken and can persist for a while after stopping the medication. These consist of:

• Fever, joint discomfort, rash, swelling, and nausea are all possible symptoms of serum sickness.

• Anemia brought on by drugs is a decrease in red blood cells that can result in symptoms like exhaustion, erratic heartbeats, and dyspnea.

• DRESS, or drug rash with eosinophilia and systemic symptoms, is characterized by a rash, a high white blood cell count, general edema, enlarged lymph nodes, and a recurrent hepatitis infection.

• Nephritis, another name for kidney inflammation, can produce fever, blood in the urine, overall edema, disorientation, and other symptoms.

What causes allergies to drugs?

Following your initial exposure to the drug (sensitization), your immune system reacts by producing immunoglobulin E (IgE) if you have a drug allergy. One kind of antibody called IgE helps in the body's removal of toxic chemicals. Numerous IgE types are produced by your body, each of which targets specific types of allergen. In your mucous membranes, skin, gastrointestinal (GI) tract, and airways, the IgE reaches cells called mast cells that contain histamine. IgE binds to the drug allergen and instructs mast cells to release histamine and other chemicals the next time you come into contact with it. Your acute allergy symptoms, which typically appear within minutes, are caused by histamine.

An allergic reaction might also be brought on by your body's T-cells. One type of white blood cell that aids in defending your body against illness is the T-cell. Your T-cells attach to the medicine because they perceive it as a foreign substance. Hives, an itchy rash, and other skin conditions are examples of the slower immune response.

How is a medication allergy diagnosed?

A medication allergy can be diagnosed by an allergist. An allergist is a medical professional who focuses on making test-based diagnoses and choosing the most effective course of action.

Before performing medication allergy testing, they will examine your medical history and might inquire about the following:

• Did You noticed symptoms for the first time when?

• What symptoms do you have?

• What was the duration of your symptoms?

• Have you taken any medication to help manage your symptoms?

• Did you have to visit the hospital or a doctor's office to get treatment for your symptoms?

• Do you take herbal supplements or vitamins?

• Does a history of drug allergies run in your family?

• Which medications, including over-the-counter ones, are you now taking?

• Which medications, including over-the-counter ones, have you taken in the past few weeks?

• Have you already experienced a medication reaction?

To identify a drug allergy, what tests will be performed?

Your allergist may recommend a skin test based on the medication they believe is responsible for the reaction. The diagnosis of a penicillin-type medication allergy can be made with the use of skin testing.

Your allergist will expose your body to trace levels of particular drug allergens during a skin prick (scratch) test. They will clean a small area of skin on your upper back or forearm and prick it with a thin needle (lancet) to check for potential drug allergies.
After being exposed to the potential allergen for 15 minutes, a positive reaction typically happens. In addition to developing a raised, round patch (wheal) that resembles a mosquito bite, your skin may turn red, gray, or white. You might have a drug allergy if you experience a positive reaction.

In rare cases, medical professionals could request a blood test. If your doctor is worried that several organ systems might be affected, a blood test might be useful in diagnosing a severe delayed reaction.

Risk factors:

An allergic reaction to a medication can happen to anyone, but some things can make it more likely. These consist of:

• A history of other allergies, such as hay fever or food allergies.

• A history of medication allergies, either personal or familial.

• Increased exposure to a medication due to prolonged use, large dosages, or frequent use.

• HIV infection and Epstein-Barr virus infection are two infections that are frequently linked to adverse medication reactions.

How do you treat a medication allergy?

The following medication allergy treatments may be suggested by your healthcare provider:

• Stop taking the drugs. Your symptoms ought to start to subside as soon as the medication leaves your body. Your doctor will recommend an alternative medication that doesn't trigger an allergic response if you're taking the medication to address a medical condition.

• Antihistamines. Antihistamines block your body from experiencing the negative effects of histamine.

• Corticosteroids. Anti-inflammatory medications called corticosteroids aid in lowering the synthesis of inflammatory molecules.

• Bronchodilators. One type of drug that helps with lung issues is a bronchodilator.

• Auto-injector for epinephrine (EpiPen®). Your doctor might recommend this device if you have serious drug allergies. The anaphylactic symptoms are promptly reversed with epinephrine. When and how to utilize it will be explained by your provider.

• Desensitization to allergies. Small amounts of medication containing the allergen are administered by a healthcare professional during allergy desensitization. Over time, your immune system will become tolerant to the allergen.  to get your body to take the medication without responding, your doctor will progressively raise the dosage over  several hours or even days.

Prevention:

The best defense against a drug allergy is to stay away from the problem medicine. You can take the following precautions to keep yourself safe:

• Inform medical professionals. Make sure your medical records accurately reflect your drug allergy. Notify other medical specialists or other healthcare providers, such as your dentist.

• Put on a bracelet. Put on a medical alert wristband that can be used to identify your drug allergy. In an emergency, this knowledge can guarantee appropriate care.

• Avoiding any medications that contain the allergen is the only method to prevent a reaction if you have a drug allergy. You might also need to stay away from similar drugs.

• To assist reduce your risk of a reaction, make sure your healthcare professionals update your medical records to reflect your drug allergy.

 References:

• Drug allergies. American College of Allergy, Asthma and Immunology. https://acaai.org/allergies/types/drug-allergies. Accessed Aug. 21, 2024.

• National Library of Medicine. Drug Allergies (https://medlineplus.gov/ency/article/000819.htm). Last updated 1/23/2022. Accessed 6/6/2023.

• Goldman L, et al., eds. Drug allergy. In: Goldman-Cecil Medicine. 27th ed. Elsevier; 2024. https://www.clinicalkey.com. Accessed Aug. 21, 2024.

• Micheletti RG, Rosenbach M, Wintroub BU, et al. Cutaneous Drug Reactions. In: Loscalzo J, Fauci A, Kasper D, et al., eds. Harrison's Principles of Internal Medicine. 21st ed. McGraw Hill; 2022.

• Burks AW, et al. Drug allergy. In: Middleton's Allergy: Principles and Practice. 9th ed. Elsevier; 2020. https://www.clinicalkey.com. Accessed Aug. 21, 2024.

• Goldman L, et al., eds. Drug allergy. In: Goldman-Cecil Medicine. 27th ed. Elsevier; 2024. https://www.clinicalkey.com. Accessed Aug. 21, 2024.

• Sousa-Pinto B. Frequency of self-reported drug allergy — A systematic review and meta-analysis with meta-regression. Annals of Allergy and Immunology. doi:10.1016/j.anai.2017.07.009. Accessed Aug. 21, 2024.