Drug Allergies

Drug Allergies

Drug allergies occur when the immune system reacts to a certain medication. The immune system becomes sensitized to one of the substances present in the drug, recognizing it as a harmful invader, much like a virus or bacteria. Once this happens, the body “remembers” the substance and, upon subsequent exposure, releases antibodies to eliminate it.

This type of allergy can be life-threatening. Therefore, if you or someone else experiences severe symptoms such as difficulty breathing, tongue or throat swelling, dizziness, rapid heartbeat, or loss of consciousness, it is critical to act immediately. Dial 911 or your local emergency service number and seek medical help at the nearest ER as quickly as you can.

Examples of a Drug Allergy

Any medication has the potential to trigger an allergic reaction, but the most common drugs associated with allergies include:

  • Antibiotics, particularly penicillin.
  • Sulfa drugs, which are a form of antibiotic containing sulfonamides.
  • Acetaminophen (Tylenol®).
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin (Bayer®), ibuprofen (Advil®), and naproxen (Aleve®).
  • Opiates, including codeine and morphine.
  • Antiseizure drugs.
  • Chemotherapy medications.
  • Contrast materials (dyes) used in some X-ray procedures to enhance imaging.

Signs and Symptoms

Allergic reaction typically starts after a few minutes of taking the medication, though the symptoms and level of severity can differ. Possible mild symptoms are:

  • Itchiness
  • Skin rash
  • Watery eyes (epiphora)
  • Running nose
  • Hives
  • Swelling (angioedema)

In more severe cases, a drug allergy can lead to anaphylaxis, a life-threatening reaction requiring immediate medical care. Severe symptoms likely to occur include:

  • Trouble swallowing (dysphagia)
  • Breathing difficulties
  • Low blood pressure
  • Dizziness or light-headedness
  • Increased heart rhythm
  • Confusion or anxiety
  • Unconsciousness

Rarely, allergic reactions may develop gradually for days or sometimes weeks upon taking the medicine. These delayed responses can persist even after discontinuing the medication and may include:

  • Fever
  • Joint pain or swelling
  • Skin rashes
  • Low red blood cell count (anemia) or low platelet count (thrombocytopenia)
  • Abnormal white blood cell count (leukocytosis or leukopenia) or elevated eosinophil count (eosinophilia)
  • Reduced kidney (nephritis) or liver (hepatitis) function
  • Enlarged lymph nodes

Causes

A drug allergy prompts the immune system to react by producing immunoglobulin E (IgE) following the initial exposure to the medicine (a process called sensitization). IgE is an antibody that aids in the elimination of dangerous substances from the body. Each type of IgE targets certain allergens, and once produced, it moves to cells containing histamine (mast cells) found in the skin, gastrointestinal (GI) tract, air paths, and mucus membranes.

Upon subsequent exposure to the drug, the IgE binds to the allergen and signals the mast cells to produce histamine as well as other chemicals. This release triggers immediate allergic symptoms, often occurring within minutes.

Additionally, T-cells, a kind of white blood cell that defends the body against infection, can also contribute to drug allergies. The T-cells identify the medication as a foreign substance and attach to it, causing a slower immune response. This normally affects the skin and leads to symptoms such as an itchy rash or hives.

Risk Factors

Although anybody can develop a drug allergy, certain factors are likely to increase the possibility of having an allergic reaction. These factors include:

  • A history of food allergies or hay fever.
  • Personal or family history of drug allergies.
  • Increased drug exposure, especially through high dosages, frequent use, or prolonged use.
  • Infections linked to allergic drug reactions, including Epstein-Barr virus infection or HIV infection.

Diagnosis

A doctor specializing in allergies (an allergist) is responsible for diagnosing a drug allergy and recommending treatment. The process begins with a thorough review of your medical history and a series of questions, such as:

  • When did your symptoms begin?
  • What symptoms did you have?
  • How long did the symptoms last?
  • What did you take or use to ease your symptoms?
  • Did you seek medical care or visit a hospital for treatment?
  • Are you currently taking any vitamins or herbal supplements?
  • Do you have a close family member with drug allergies?
  • What drugs are you taking at the moment, including non-prescription?
  • Have you used any medications in the last few weeks?
  • Have you experienced reactions to other medicines in the past?

Tests for Drug Allergy

Based on your answers and the suspected drug, your allergist may recommend skin testing. This is particularly useful for the diagnosis of penicillin-type medication allergies.

A skin prick (scratch) test involves exposing the body to small amounts of potential drug allergens. The allergist will first clean part of the skin in the upper back or forearm and prick the skin using a lancet with the allergens.

A positive response will occur within 15 minutes following exposure. It can cause changes in skin color (gray, red, or white) and the development of an elevated, round patch (wheal) resembling a mosquito bite. A positive reaction also suggests a possible drug allergy.

In some cases, a blood test may be ordered, especially if the allergist is concerned about a delayed reaction or multiple organ systems being affected. This test helps identify severe or complex allergic responses.

Treatment and Management

If you are diagnosed with a drug allergy, your allergist may suggest the following treatment options:

  • Discontinue the drug. As soon as the drug is cleared from your system, symptoms should begin subsiding. If the medication is essential for treating a particular condition, your GP will prescribe an alternative that doesn’t trigger an allergic reaction.
  • These work by blocking the effects of histamine.
  • These anti-inflammatory medicines help lessen the body’s release of chemicals contributing to inflammation.
  • If the allergy affects your lungs, bronchodilators can help ease the symptoms caused.
  • Epinephrine auto-injector (EpiPen®). For severe drug allergies, such as those causing anaphylaxis, your physician may prescribe an epinephrine auto-injector. Epinephrine rapidly counteracts the severe symptoms of anaphylaxis, and your provider will instruct you on how and when you should use it.
  • Allergy desensitization. This treatment involves gradually introducing small amounts of the allergen-containing drug to your system. Over time, your immune system can form a tolerance to the allergen. The process, which involves increasing doses over several hours or days, allows the body to accept the medication without overreacting.

Prevention

The best way to prevent a drug allergy reaction is to avoid the medication that triggers it. Here are steps you can consider in order to protect yourself:

  • Informing your doctor: Ensure your drug allergy is noted in your medical records. Always inform healthcare providers, including dentists or other specialists, about your allergy before receiving any treatment or medication.
  • Wearing a medical alert bracelet: Use a medical alert bracelet that shows your drug allergy. This can help emergency responders and healthcare professionals provide the right treatment in urgent situations.

Living With a Drug Allergy

How to care for yourself

Managing a drug allergy requires vigilance and proactive measures to protect yourself. To effectively care for yourself, always let healthcare professionals know about your drug allergy before receiving any treatment, including dental care, surgeries, or over-the-counter medications. Also, in case of emergencies, ensure your drug allergy information is easily accessible. Some options include:

  • Smartphone health app: Save your allergy information in a health app that is visible from your lock screen.
  • Medical alert jewelry: Wear a bracelet or necklace that identifies your drug allergy.
  • Laminated allergy card: Keep a card with detailed information in your wallet or purse.
  • Tattoo: You can opt for a tattoo indicating your allergy, placed in a visible location.

Takeaways

For most individuals, medications are vital in managing symptoms or treating illnesses. However, for some, their immune system mistakenly identifies certain drugs as threats, triggering an allergic reaction. The severity of these reactions can vary widely. While mild cases might result in troublesome symptoms such as congestion, rash, or watery eyes, severe reactions can impact breathing or heart pulse. In rare cases, it can become life-threatening.

So, if you experience allergy symptoms after using a medication, it’s crucial to consult a healthcare provider. They can perform tests to confirm a drug allergy and suggest alternative treatments that are safe for you. Seeking timely medical advice also ensures your safety and helps you avoid potential complications.

 

 

 

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