Drug and Medication Allergies

We take drugs and other medications to combat illness, control pain, or improve our health. Sometimes our bodies treat these introduced agents as harmful rather than helpful. If that happens to you, you may have a drug allergy. Providers at Baptist Health will provide you with necessary care while also being sensitive to any allergic conditions you might have. 

What Are Drug Allergies?

Drug allergies occur when your body reacts negatively to the presence of a particular medication or substance. The root cause of drug allergies is similar to that of other types of allergies: the hypersensitivity of the immune system to certain “invading” or “foreign” elements. Your body wants to work against the drug rather than with it.

Drug allergies are relatively rare, occurring only about five to ten percent of the time. They range in intensity from mild to severe. Some reactions occur almost immediately on ingestion, when your body produces an antibody known as Immunoglobulin E, or IgE, that results in common allergy symptoms. At other times, the reaction is delayed. The production of a particular type of white blood cell, called a T cell, can generate rashes and other immune responses several weeks after consumption of the drug. 

What Are the Symptoms and Signs of Drug Allergies?

Common signs and symptoms of a drug or medication allergy include:

• Itchy, watery eyes
• Coughing and wheezing
• Runny nose and mucous drainage 
• Itchy skin, hives, or rashes
• Shortness of breath
• Fever

In rare cases, taking a drug can trigger anaphylaxis, an extreme and possibly fatal allergic reaction. Anaphylaxis is marked by:

• Swollen throat, lips, or tongue
• Impaired breathing
• Skin rashes or hives
• Rapid pulse
• Dizziness, lightheadedness, or fainting
• Change of color in the face or body (turning pale or red)
• Gastrointestinal pain
• Vomiting or diarrhea
• Uterine cramps

It’s important to note that drug allergies are not the same as drug side effects. The latter are known to science and listed on the drug label. A drug allergy is also different from drug toxicity, which is generally caused by taking a medication differently than as prescribed (e.g., overdosing).

What Are the Triggers of Drug and Medication Allergies?

Any drug or medication, whether over-the-counter, prescription, or herbal, can trigger an allergic reaction. However, some drugs are more likely to be allergens than others. These include:

• Antibiotics, such as penicillin, amoxicillin, and tetracycline
• Aspirin
• Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen
• Sulfa drugs
• Insulin
• ACE inhibitors, such as Lotensin
• Antiseizure drugs
• Muscle relaxants
• Monoclonal antibody therapy agents
• Chemotherapy drugs
• HIV drugs

Certain risk factors increase the probability of an adverse drug reaction. These include:

• A family medical history of drug allergies
• A personal medical history of other types of allergies (e.g., hay fever or mold allergies)
• Increased drug use, either in dosage or frequency
• Medical conditions, such as HIV or the Epstein-Barr virus

How Do I Know If I Have a Drug Allergy?

Drug allergies can be difficult to diagnose because many of the symptoms are associated with a number of other medical conditions. You will need to see your physician for a proper evaluation. He or she may take the following steps to diagnose your case:

• Conduct a physical examination
• Document your symptoms and family medical history
• Conduct a skin-prick test (effective in identifying a penicillin allergy)
• Administer a blood test for evidence of a delayed allergic reaction, especially one that involves multiple organ systems (sometimes called DRESS syndrome for “drug rash with eosinophilia and systemic symptoms”)
• Conduct an oral drug challenge

An oral drug challenge involves taking a dose of the suspected allergen while under medical supervision. Challenges are only conducted in those cases where, based on past history, the allergic reaction is expected to be moderate or mild.

Drug Allergy Prevention and Treatment

The chief means of treating a drug allergy is to avoid taking the medication that causes the reaction. If you have a drug allergy:

• Inform your physician and other medical providers of your situation
• Wear an emergency medical bracelet that identifies your allergens
• Learn which groups of drugs to avoid, based on their related properties
• Ask for alternatives that accomplish the same medical ends through different chemical means

If there are no viable alternative medications, your physician may arrange for you undertake a desensitization treatment. This typically occurs in a hospital setting, where you can be monitored as you are administered slightly larger dosages of a drug on a regular schedule until you develop some level of tolerance for it. Desensitization is only effective with drugs taken daily.

The most serious type of drug reaction, anaphylaxis, calls for immediate medical attention. Anaphylaxis is treated with epinephrine (also called adrenaline). Pre-loaded epinephrine auto-injectors are available by prescription. At-risk allergy sufferers should be aware of the early signs of anaphylaxis and carry one or more epinephrine auto-injectors at all times.