Do You Need to Strengthen Your Immune System After Taking Antibiotics?

Antibiotics save lives by treating bacterial infections and by preventing infections in people at risk. You may have heard that antibiotics are bad for your immune system or that they cause diarrhea. The truth is that the world is a safer place with antibiotics, but you need to use them wisely.

"In general, taking an antibiotic should not weaken your immune system, and they are often necessary to fight bacterial infections that could worsen without treatment," says A. Ben Appenheimer, MD, infectious disease specialist and assistant professor in internal medicine at University of Iowa Hospitals and Clinics in Iowa City.

"While antibiotics don't weaken your immune system, they can increase your risk of other types of infection, namely Clostridium difficile, or C. diff diarrhea, but this is not due to their effect on the immune system."

​Read more:​ Diarrhea After Antibiotics? Here's How to Get Back on Track

While your immune system is intact, your gut system may take a hit while taking antibiotics. C. diff infection is a possible side effect of antibiotics, according to the Centers for Disease Control and Prevention (CDC). It causes severe diarrhea, can lead to severe colon damage and in some cases can be life-threatening.

C. diff occurs because antibiotics change the bacteria balance in the gut. "We have healthy bacteria throughout our bodies and our digestive tract. We call this the microbiome," Dr. Appenheimer says. "Good bacteria in our digestive tract compete with certain types of bad bacteria, like C. diff. When we take antibiotics, it kills some of the good bacteria, creating space for other bacteria like C. diff to flourish."

Typically, at some point, your gut bacteria bounce back. When this happens after taking antibiotics depends on many factors, like your general health and the specific antibiotics taken. In one very small October 2018 study in ​Nature Microbiology​, six weeks after taking a strong mix of antibiotics for four days, the microbiome of 12 people assigned male at birth was close to normal. Nine common species were still undetectable 6 months later.

Some people wonder if probiotics can help speed that process along. It's possible, Dr. Appenheimer says, but the jury is still out.

"One would think that taking probiotics could prevent this type of secondary infection. However, the data looking at this are mixed, with some showing benefit and others showing no effect," he says.

The Infectious Disease Society of America guidelines state there is insufficient data currently, he adds. "In general, probiotics are felt to be safe, but they are also expensive, and the benefit in preventing C. diff hasn't been definitively proven."

It's important to note that using too many antibiotics in populations can cause problems over time, namely antibiotic resistance, which occurs when bacteria evolve to outsmart the antibiotics designed to kill them, according to the CDC.

As more bacteria learn how to resist more antibiotics, bacterial infections become more dangerous and harder to treat. Close to 3 million antibiotic-resistant infections occur every year, and they kill more than 35,000 people, according to the CDC.

That's why it's crucial to only take antibiotics as prescribed. "Limit the use of antibiotics to only those situations that are necessary," Dr. Appenheimer says. "Only take antibiotics when prescribed by physicians, and I would avoid pressuring doctors to prescribe antibiotics in situations where they feel they are not warranted."

The CDC and U.S. National Library of Medicine add these tips for the safe use of antibiotics:

• Remember that antibiotics are only for bacterial infections. Don't ask for an antibiotic to treat a cold.
• Always follow your doctor's directions and finish your prescription, even if you feel better.
• Don't save some antibiotics for later or share them with others.

"As always, a well-balanced diet, adequate sleep and limiting stress will help keep you healthy, and that remains the same before, during and after a course of antibiotics," Dr. Appenheimer says.

​Read more:​ 12 Science-Backed Ways to Improve Your Gut Health