December 9, 2022

What to know about side effects and allergic reactions to antibiotics

People often come to the emergency room with a long list of antibiotics that they say they are allergic to. The problem with this is that there may not be many options left for the doctor to prescribe once so many antibiotics are ruled out.

While there are legitimate, life-threatening antibiotic allergies, people can also mistake something else for an allergy. There is no allergy test for every antibiotic. Yes, allergies to some antibiotics can be hereditary, but just because a parent is allergic to an antibiotic doesn’t mean the child will necessarily be. Parents will say, “I had a bad reaction or I’m allergic to penicillin, so I don’t want my child to get the antibiotic. This just eliminated one of the most common antibiotics.

And remember, antibiotics can only be used to

certain types of bacterial infections
. They are not effective against viral infections like the common cold, flu, or COVID-19.

Common Side Effects of Antibiotics

Often what people think is an allergy may just be a common side effect. It’s important to know

the difference between an allergy and a side effect
. Side effects can occur naturally or when an antibiotic is not taken correctly. These are normal events and not a sign of an allergy. Here are some of the most common side effects of antibiotics:

• Skin rash (may be from sun sensitivity when taking an antibiotic)
Bloody diarrhea (adults), thrush (baby) – These may be signs that you or a child have been taking an antibiotic for too long.
stomach pain
Nausea / upset stomach
Muscle pain

If you experience any of these side effects, contact your doctor to discuss next steps. Your doctor can either adjust your dosage or switch you to another antibiotic.

Read the label

There are many reasons why a person may experience a side effect after taking an antibiotic. One of the main reasons is that the person does not take it exactly as directed. That’s why it’s important to read the label and follow the directions! For instance:

• Take as directed. If the label says to take the antibiotic on an empty stomach, with water, or with food, do so.

• Pay attention to time.
If you are supposed to take the antibiotic every 12 hours, follow that timeframe. If you go outside the prescription parameters, you may experience side effects.

• Store properly.
Some antibiotics need to be refrigerated.

• Complete the entire course of antibiotics.
Be sure to take the antibiotic for the prescribed length of time. If you have been asked to take an antibiotic for a certain number of days and there are some left after that time, dispose of it properly. Do not save the antibiotic for future use. Not all bacteria are treated with the same antibiotic, and

taking expired medicines can be harmful

• Watch the dosage.
If you miss a dose, wait for the next dose. Don’t double. Depending on which antibiotic it is, talk to your doctor or pharmacist. If you have any left, throw it away.

• Never share an antibiotic.
This is especially important for children (including siblings in the same family, for example). Doctors base the dosage on the patient’s weight. And the adults

shouldn’t share antibiotics
. If another family member begins to show symptoms, they should contact their primary care physician or emergency care (if their physician is unavailable) to ensure they are receiving the correct antibiotic at the correct dose for the specific infection from which he suffers. Doctors are the experts in matching the disease with the best treatment.

Other Ways to Reduce Side Effects

A way of

reduce the risk of side effects is to take probiotics

such as yogurt, kefir, kimchi or sauerkraut. Since antibiotics can kill healthy bacteria as well as disease-causing bacteria, you need to replenish the good bacteria in your gut.

Another way to reduce the risk of side effects is to avoid drug interactions by

tell your doctor about the medications you are taking

before taking an antibiotic. This includes things like over-the-counter medications that can interact with certain antibiotics. Often people forget to mention over-the-counter medications and vitamins.

For example, some common heart medications come from natural sources. If you are taking any other herbal or natural medicines, your doctor needs to know. Mixing medications from natural sources can cause unintended interactions.

Additional things to keep in mind

• Antibiotics do not treat COVID-19.
COVID-19 is a virus and antibiotics only treat bacterial illnesses; they cannot treat viruses. Antibiotics may be given to someone with COVID-19 to treat a second respiratory infection, such as pneumonia. However, this will not cure them of COVID-19.

• Try giving antibiotics to children yourself.
The vast majority of antibiotics are administered in one or two doses per day. It would be better

give the antibiotic to your child

yourself, rather than asking someone at your child’s school or daycare to give it to them. Most pediatricians try to keep in mind where children are during the day and what they are doing before prescribing.

• Antibiotics circulate in breast milk.
If you are breastfeeding, consult your doctor before taking antibiotics. Some antibiotics are not recommended while breastfeeding because they could stain your baby’s teeth or cause diarrhea or other problems.

This article was originally published on

IBX Overviews

About Dr. Lynn Collins

I’m the pediatric medical director at Independence Blue Cross. In my current role, I am responsible for utilization review, policy review and resolution of any pediatric concerns. I received my medical degree from the University of Florida College of Medicine and am board certified in pediatrics.