Antibiotics are a type of medication that fight bacteria. They work either by killing bacteria or by stopping it from reproducing.

These drugs often cause gastrointestinal side effects, such as:

These side effects may be uncomfortable, but they tend to pass quickly.

Eating the right foods can help to prevent bothersome side effects and encourage healing. In this article, learn which foods to eat and which to avoid while taking antibiotics.

Man taking antibiotics with water.
Certain foods or drinks may affect antibiotics.

A person has trillions of bacteria and other microorganisms living in their gut. The medical community refers to these organisms, collectively, as the gut microbiome.

Antibiotics fight bacteria, and they can upset the balance of bacteria in the microbiome.

The gut microbiome keeps the digestive system functioning and helps the immune system to defend against viral infection.

When antibiotics upset the bacterial balance, a person may experience side effects, such as nausea or diarrhea. Consuming probiotics and prebiotics during and after a course of antibiotics can help to restore the balance of bacteria in the gut.

Probiotics

Probiotics are live microorganisms commonly known as "healthy bacteria."

They can help to reduce some of the side effects of antibiotics, such as bloating and diarrhea.

While research about probiotics and antibiotics is still inconclusive, that taking probiotics is a safe way to prevent antibiotic-related diarrhea.

Antibiotics can kill the beneficial bacteria in probiotics, so it is advisable to take the two a few hours apart.

After finishing a course of antibiotics, taking a mixture of probiotics can also help to restore balance in the microbiome.

Prebiotics

Prebiotics are food for the beneficial bacteria that live in the gut microbiome.

Feeding the beneficial bacteria before and after taking antibiotics can help to bring balance back to the gut.

Some foods contain low levels of prebiotics, such as:

Manufacturers sometimes add prebiotics to foods, such as:

  • yogurt
  • infant formula
  • cereals
  • bread

Prebiotics may appear on food labels as:

  • galactooligosaccharides, or GOS
  • fructooligosaccharides, or FOS
  • oligofructose, or OF
  • chicory fiber
  • inulin

Most prebiotics are dietary fibers. If a person consumes large quantities, they may experience gas or bloating.

Anyone who is considering adding prebiotics to their diet should do so slowly to allow their gut to adapt.

Fermented foods

Fermented foods are good sources of beneficial bacteria. All fermented foods contain microorganisms, but some heat or filtration processes can kill the beneficial bacteria.

Fermented vegetables, such as sauerkraut or pickles in jars and stored at room temperature, do not contain live cultures.

Microorganisms do not survive any baking processes, so they will not be present in foods such as sourdough bread.

Foods that contain these organisms often have "live and active cultures" on their labels.

Fermented foods include:

  • miso
  • tempeh
  • kimchi
  • yogurt
  • traditional salami
  • some cheeses
  • fresh, sour dill pickles

Vitamin K

Basket of kale
Kale is high in vitamin K.

Antibiotics fight all kinds of bacteria, even those that help the body. Some bacteria produce vitamin K, which the body needs to make the blood clot.

To reduce the impact of antibiotics on vitamin K levels, people can eat:

  • kale
  • spinach
  • turnip greens
  • collards
  • Swiss chard
  • parsley
  • mustard greens
  • Brussels sprouts

Fiber

Fiber may stimulate the growth of beneficial bacteria in the gut.

People should avoid high-fiber foods while taking antibiotics, as they may affect how the stomach absorbs the medicine.

However, once a person finishes the full course of antibiotics, eating fiber can help to restore the beneficial bacteria and promote proper digestion.

Foods that are rich in fiber include:

  • artichokes
  • bananas
  • berries
  • beans
  • broccoli
  • lentils
  • nuts
  • peas
  • whole grains