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Answers to your antibiotic questions

Last Modified: January 21, 2022

Family Medicine


According to the Centers for Disease Control and Prevention (CDC), more than 266 million courses of antibiotics were prescribed in 2014. With so many people taking these medications, it’s important to understand how they work and instances when they might not. We tapped Jacob Nafziger, DO, PPG – Family Medicine, to answer some of the most common questions.

How do antibiotics help fight illness?

Antibiotics are medications that are specially designed to fight infections that are caused by bacteria. There are many different types of bacteria, and subsequently, many different types of antibiotics. When  doctors think you have a bacterial infection, we will use the antibiotic that targets the bacteria we think is most likely causing the infection.

What types of illness benefit from antibiotic treatment?

Any infection that is caused by a bacteria would benefit from an antibiotic. Most commonly, these include bacterial sinus infections, urinary tract infections and pneumonia.

As we are in the heart of cold and flu season, it’s important to keep in mind the vast majority of these illnesses are caused by viruses, which, unfortunately, antibiotics are not effective against. When it comes to COVID, Influenza, and a few other viruses, we do have helpful tests at our disposal to tell us if these viruses are present. But that isn’t always the case. Often, we don’t have a test to tell us what virus is causing the infection, but we are able to pick up on certain "clues" about the course of an illness that will help us decide if an antibiotic is beneficial.

It’s important to keep in mind that viruses cause sinus infections, ear infections, sore throats and other cold-like symptoms. Viruses can also cause that green or yellow thick mucus and phlegm. Color alone does not indicate bacteria vs virus.

One clue that is helpful is how long symptoms have been going on. Usually, a viral upper respiratory infection will start to improve within 7-10 days. If symptoms have been going on longer than that and not improving it is most likely a bacterial infection. Secondly, bacteria are smart. They like to recognize when our immune system is distracted fighting off a viral illness and sneak in to cause a second infection. For the patient, this often presents as cold-like symptoms for a week or so, improvement for a day, and then worsening symptoms following that. In those instances, an antibiotic would be helpful.

What are the risks of taking antibiotics when they are not beneficial?

There are multiple risks of taking an antibiotic for something that might not be a bacterial infection. First, antibiotics come with many side effects, including nausea, vomiting, diarrhea, and sometimes even other, more severe bacterial infections.

Secondly, over time bacteria evolve to become resistant to certain antibiotics. This means that an antibiotic that worked a few years ago for a certain infection may not work today. This is how MRSA, or methicillin resistant staph aureus, developed. What was once an easily treatable bacteria now can only be killed with certain antibiotics. This becomes very problematic, particularly in hospitals and nursing homes; areas where patients are generally sicker at baseline and where we have fewer and fewer medications at our disposable to take care of them.

Are there any measures patients should take to keep their gut healthy while taking antibiotics or following?

Probiotics, specifically Lactobacillus and Saccharomyces, have been shown to significantly decrease the risk of antibiotic-associated diarrhea. However, the amount of probiotic, how often to take it, and how long to take it is not known. There are some specific circumstances in which a patient should not take a probiotic, but for the most part, they can help decrease diarrhea associated with antibiotic use.

Do antibiotics counteract any other medications patients might be taking?

There are many things your doctor needs to consider when prescribing an antibiotic. Besides the large side effect profile that antibiotics come with, there are other, more specific factors we must consider. Some antibiotics will increase or decrease the effectiveness of other medications, particularly the blood thinner Warfarin. Some antibiotics can affect your heart rhythm, some can make it easier to get sunburned. Some antibiotics increase the risk of a tendon rupturing. For some patients with kidney disease, their antibiotic dose will need to be adjusted to accommodate the decrease in kidney function.

How long should a patient take antibiotics?

Duration of antibiotic use depends on the antibiotic being prescribed and what the infection is that is being treated. It is very important to take the antibiotic prescription in its entirety, even if you are starting to feel better before completing the course. This is to ensure the entire infection is treated and to help decrease antibiotic resistance to that infection.

If you are not starting to feel better within the first few days of taking your antibiotic, or if you are experiencing significant side effects, be sure to reach out to your doctor to let them know. We’re here to make sure you get back to feeling better.


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