Drug allergies and drug reactions are two different types of adverse drug events that can cause serious health problems. Learn how to tell them apart.
Have you ever experienced an unpleasant or harmful effect after taking a medication? If so, you may have had a drug reaction or a drug allergy.
But what is the difference between these two terms, and how can you prevent them?
In this blog post, we will explain the causes, symptoms, and treatments of drug reactions and drug allergies, and how to use a drug interaction search tool to avoid potential problems. Read on to learn more!
What is a drug allergy?
A drug allergy is an abnormal reaction of your immune system to a medication. Your immune system mistakenly identifies the drug as a harmful substance and produces antibodies to fight it.
The next time you take the same or a similar drug, these antibodies trigger an allergic reaction.
The symptoms of a drug allergy can vary from mild to severe, depending on the type and amount of the drug, the sensitivity of your immune system, and other factors.
Some common symptoms include:
- Hives, itching, or rash
- Swelling of the face, lips, tongue, or throat
- Difficulty breathing or swallowing
- Wheezing or coughing
- Nausea, vomiting, or diarrhea
- Dizziness or fainting
- Anaphylaxis, a life-threatening reaction that can cause shock, low blood pressure, and organ failure
Some drugs are more likely to cause allergic reactions than others. These include:
- Antibiotics, such as penicillin, cephalosporins, and sulfonamides
- Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, ibuprofen, and naproxen
- Anticonvulsants, such as phenytoin and carbamazepine
- Chemotherapy drugs, such as cisplatin and paclitaxel
- Biological agents, such as monoclonal antibodies and vaccines
What is a drug reaction?
A drug reaction is an unwanted or unexpected effect of a medication that is not related to your immune system. It can be caused by various factors, such as:
- The pharmacological properties of the drug, such as its mechanism of action, dosage, metabolism, or elimination
- The interaction of the drug with other drugs, foods, beverages, or supplements
- The individual characteristics of the patient, such as age, weight, gender, genetics, medical conditions, or liver or kidney function
The symptoms of a drug reaction can also vary from mild to severe, depending on the type and amount of the drug, the presence of other substances in your body, and other factors.
Some common symptoms include:
- Headache, drowsiness, or fatigue
- Nausea, vomiting, or diarrhea
- Constipation or dry mouth
- Mood changes or confusion
- Muscle pain or weakness
- Bleeding or bruising
- Liver damage or kidney failure
Some examples of drugs that can cause reactions are:
- Antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs)
- Anticoagulants, such as warfarin and heparin
- Opioids, such as morphine and codeine
- Statins, such as atorvastatin and simvastatin
- Corticosteroids, such as prednisone and hydrocortisone
How to tell the difference between a drug allergy and a drug reaction?
It can be difficult to tell the difference between a drug allergy and a drug reaction based on the symptoms alone.
However, there are some clues that can help you distinguish them:
The timing of the symptoms
A drug allergy usually occurs within minutes to hours after taking the drug for the first time or after repeated exposure. A drug reaction can occur at any time during the course of treatment.
The type of symptoms
A drug allergy typically causes skin rashes or hives; swelling; breathing problems; or anaphylaxis. A drug reaction can cause various symptoms depending on the drug and the patient.
The history of exposure
A drug allergy requires previous exposure to the same or a similar drug to sensitize your immune system. A drug reaction can occur with any dose of any new or old drug.
The response to treatment
A drug allergy usually improves with antihistamines or corticosteroids; epinephrine for anaphylaxis; and discontinuation of the offending drug.
A drug reaction may require dose adjustment; switching to another drug; supportive care; or antidotes for toxicity.
How to prevent a drug allergy or a drug reaction?
The best way to prevent a drug allergy or a drug reaction is to avoid taking drugs that you are allergic to or that may cause unwanted effects. To do this:
- Inform your doctor about any allergies or reactions you have had to any medications in the past.
- Inform your doctor about any other medications, supplements, or herbal products you are taking or plan to take.
- Inform your doctor about any medical conditions or genetic factors that may affect your response to medications.
- Read the labels and instructions of any medications you are prescribed or buy over-the-counter. Follow the directions carefully and do not exceed the recommended dose or duration of use.
- Check for potential interactions between your medications and other substances, such as foods, beverages, or alcohol.
- Monitor your symptoms and report any changes or concerns to your doctor. Seek immediate medical attention if you experience severe or life-threatening symptoms, such as anaphylaxis.
