Antibiotics: Side Effect vs. Allergy

When I worked in the emergency department, people would come in with a mile-long list of antibiotics they said they were allergic to. The problem with ruling out numerous antibiotics is that then there is little left to give a person. There are no magic potions. The patient would say, “You’re the doctor, what can I take?” I’d think to myself, “There are not many options left!”

While there are legitimate life-threatening allergies to antibiotics, people may also be mistaking something else for an allergy. There isn’t an allergy test for every antibiotic. Yes, allergies to certain antibiotics may run in the family, but just because a parent is allergic to an antibiotic, it does not necessarily mean the child will be. Parents will say, “I had a bad reaction or I’m allergic to penicillin, so I don’t want my child to have the antibiotic.” That has just eliminated one of the most common antibiotics out there.

And remember, antibiotics can only be used for some types of bacterial infections. They are not effective against viral infections like the common cold, the flu, or COVID-19. 

Common Side Effects of Antibiotics

A lot of times what people think is an allergy, may just be a common side effect. It’s important to know the difference between and allergy and a side effect. Side effects may occur naturally, or they can happen when an antibiotic is not taken properly. They are normal occurrences, and not the sign of an allergy. These are some of the most common side effects of antibiotics:

Rash (could be from sun sensitivity while taking an antibiotic)
Diarrhea
Bloody diarrhea (adults), thrush (baby) — These can be signs that you or a child have been taking an antibiotic for too long.
Stomach pain
Nausea/upset stomach
Vomiting
Fatigue
Muscle pain

If you experience any of these side effects, contact your doctor to discuss next steps. Your doctor may either adjust your dosing 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 is not taking it exactly as directed. That is why it’s important to read the label and follow the directions! For example:

Take as directed. If the label says to take the antibiotic on an empty stomach, with water, or with food, then do that.
Be mindful of the time. If you are supposed to take the antibiotic every 12 hours, follow that timeline. If you go outside the prescription parameters, you may experience side effects.
Store properly. Some antibiotics need to be refrigerated.
Complete the entire antibiotic course. Make sure you take the antibiotic for the prescribed length of time. If you were directed to take an antibiotic for a set number of days, and have some left over after that timeframe, properly dispose of it. Do not take the antibiotic for future use. Not all bacteria are treated with the same antibiotic, and taking expired medication can be harmful.
Watch the dosing. If you miss a dose, wait for the next dose. Do not double up. Depending on what it is, talk to your doctor or your pharmacist about it. If you have any left over, throw it out.
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 adults shouldn’t share antibiotics If another family member starts showing symptoms, they should contact their primary care doctor or urgent care (if their doctor is unavailable) to ensure that they get the right antibiotic at the right dose for the specific infection they have. Doctors are the experts in matching the illness with the best treatment.

Other Ways to Reduce Side Effects

One way to reduce the chance of side effects is by taking probiotics such as yogurt, kefir, kimchi, or sauerkraut. Since antibiotics can kill healthy bacteria along with disease-causing bacteria, you need to replenish the good bacteria in your gut.

Another way to reduce the chance of side effects is to avoid any drug interactions by letting your doctor know what medications you are on before taking an antibiotic. This includes things like over-the-counter drugs that can interact with certain antibiotics. Oftentimes, people forget to mention over-the-counter drugs and vitamins.

For example, there are some common cardiac medications that come from natural sources. If you are on other herbal or natural drugs, your doctor needs to know. Mixing medications from natural sources can cause unintended interactions.

Additional Things to Keep in Mind

Antibiotics don’t treat COVID-19. COVID-19 is a virus, and antibiotics only treat bacterial illnesses; they cannot treat viruses. Antibiotics may be given to someone who has COVID-19 in order to treat a second respiratory issue, like pneumonia. It won’t cure them of COVID-19, however.
Try to administer antibiotics to children yourself. The vast majority of antibiotics are given on a once- or twice-a-day regimen. It’s best to give the antibiotic to your child yourself, rather than having someone at your child’s school or daycare give it to them. Most pediatricians try to keep in mind where the children are during the day and what they are doing before prescribing.
Antibiotics travel through breast milk. If you are breastfeeding, consult your doctor before taking any antibiotics. Some antibiotics are not recommended when breastfeeding as they could stain your baby’s teeth or cause diarrhea or other concerns.