You’ve started taking a new medication. And while you know all drugs have the potential to cause mild side effects, you’re wondering if what you’re experiencing is something more – like an allergic reaction.
Allergic reactions are not very common for most medications, but they can happen and should be taken seriously.
Here, we’ll go over what drug allergies are and what can cause them. We’ll also cover the possible signs and symptoms of an allergic reaction to a medication, how they differ from drug side effects and drug interactions, and how to respond when a drug allergy happens.
What a drug allergy is and possible causes
Your immune system is your body’s natural defense against infection. So when your immune system senses germs or other harmful substances, it responds to fight those substances.
With a drug allergy, your immune system can mistakenly identify the medicine you’re taking as unwanted, which triggers a reaction. This can happen when you first take a new drug, but it can also happen after repeated uses, as some allergic reactions take time to develop.
Signs and symptoms you may be allergic to a medication
Some allergy symptoms are so mild, you may not even know you’re having an allergic reaction to your medication. In rare instances, symptoms can be severe and even life threatening, like anaphylaxis.
Anaphylaxis is characterized by facial, throat and tongue swelling, which can make it hard to breathe. Racing pulse, nausea and dizziness can also be symptoms of an allergic reaction.
Call 911 immediately if you think you or someone else is experiencing an anaphylactic reaction.
Mild to moderate drug allergy symptoms and treatment
Symptoms of a mild to moderate drug allergy can occur anywhere from an hour to weeks after taking a medication. They may include:
- Blotchy skin rash
- Itching of the skin or eyes
- Raised, itchy skin welts known as hives
- Warm and red skin
- Wheezing or trouble breathing
If you are experiencing moderate drug allergy symptoms, stop taking the medication right away and contact your doctor or pharmacist.
Mild to moderate reactions are often treated with:
- Albuterol for breathing problems
- Antihistamines for hives, rashes or itching
- Steroids for swelling
Severe drug allergy symptoms and treatment
Also known as anaphylactic shock, anaphylaxis is the most serious allergic reaction. Anaphylaxis is not common, but if an anaphylactic reaction does occur it can happen within one hour of taking a drug. Anaphylactic shock can be life threatening if not treated right away.
If you think you’re experiencing anaphylaxis, first administer an epinephrine injection if you have one on hand, then call 911 immediately after.
An epinephrine injection can only pause anaphylactic reaction – it can’t treat it. You will still need to go to the emergency room for treatment and observation.
Signs and symptoms of anaphylaxis include:
- Difficulty breathing
- Dizziness
- Fainting
- Nausea or vomiting
- Pale or flushed skin or itchy, red rash
- Swelling of the face, throat and tongue
Drugs that can cause an allergic reaction
Any prescription and over-the-counter medication can potentially cause an allergic reaction, but some medications are more likely to trigger them. These include:
- ACE inhibitors for treatment of high blood pressure
- Antibiotics that have sulfonamides (sulfa drugs)
- Antihistamines
- Antiretroviral drugs, like those that treat HIV
- Antiviral drugs, like those that treat the flu or COVID-19
- Chemotherapy drugs
- Common antibiotics, like amoxicillin and penicillin
- Dyes used during X-rays
- Insulin
- Local and general anesthetics, like those used for surgeries and procedures
- Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen
- Psychotropic medication, like antidepressants
Is it a drug sensitivity, drug interaction or drug allergy?
Many people who have a reaction to a new medication aren’t allergic. A true allergy causes an immune system response with symptoms that range from mild to life threatening and can require treatment. But some people experience side effects and sensitivities to medication. These are typically mild, don’t require treatment and usually go away once you stop taking the drug.
Other drugs you’re taking, food and drinks you’re consuming, and health conditions you’re managing may also interact with a new medication and cause you to experience side effects. That’s why it’s important to read and follow medication instructions exactly. It’s also important to be completely honest with your doctor about what else you’re ingesting, so your doctor can help you avoid an interaction and prescribe what’s right for you.
If you do experience a true allergic reaction to a specific medicine, you may also be allergic to other medicines of the same class. If that’s the case, your doctor will likely recommend a type of medicine from a different class for treatment of whatever’s ailing you.
If you experience symptoms of an allergic reaction to a drug you’re taking, you may not necessarily be allergic to that particular drug. To receive a proper diagnosis, your doctor will likely ask about the symptoms you experienced and when you experienced them.
Your doctor will then ask you what medications you’re on. It’s important to include all medications – prescription, over the counter, vitamin supplements and herbal medicines – so your doctor can order specific tests to determine exactly which drug may be causing you problems. From there, your doctor may order allergy tests.
Other options for avoiding allergic reactions to your medication
The pharmacist at your local pharmacy is a great resource when it comes to managing multiple medications. You can ask to speak about possible allergies or interactions when you pick up your prescription.
If you’re a HealthPartners insurance member, you can enroll in our medication therapy management (MTM) program. In the MTM program, you’ll work one-on-one with a pharmacist who specializes in medication interactions, alternatives and affordability, and who is dedicated to ensuring your medications work well together.
Sometimes, you can’t stop taking a drug you need even if you’re mildly allergic, for instance, if you have a serious infection or cancer. In this case, you may work with your doctor to start with a small dose of the medication and gradually increase the dosage, while your doctor monitors your body’s reactions. This method isn’t always risk-free, but in certain situations it’s better than letting the condition go unmedicated.
If you don’t necessarily need the drug you’re allergic to, like certain types of over-the-counter drugs or antibiotics, it’s best to just avoid them. If you really do need them, work with your doctor to determine what’s best for you.
Preventing an allergic reaction to your medication
If you think you’re experiencing mild signs of an allergic reaction to your medication, call your doctor or clinician. If there is a concern, your doctor will work with you to determine an alternative medication to avoid side effects and make sure you’re getting the most out of your medications.
If you’re experiencing a severe reaction, call 911 or go to the emergency room immediately.
If you have a known drug allergy, make sure to inform all your health care providers, including your dentist, who will ensure it’s in your medical records.
