4 Food and Drinks to Avoid While Taking Sulfamethoxazole / Trimethoprim (Bactrim)

Bactrim is an antibiotic often used to treat urinary tract infections (UTIs). It’s also used to treat infections of the skin, lung, and gut. Bactrim is actually a combination of two medications:  sulfamethoxazole and trimethoprim. It works by interfering with the DNA and protein production that bacteria use to grow. 

Bactrim can cause an upset stomach, so limiting foods that can irritate the stomach may make taking this antibiotic easier. That said, there aren’t many foods you need to avoid when taking Bactrim. Let’s look at some of the foods to avoid or limit while on Bactrim. 

1. Acidic foods

Bactrim is absorbed rapidly in the gut. This means that unlike some other antibiotics, Bactrim is easily digested regardless of what you drink or eat with it. So there aren’t any foods to avoid while taking Bactrim to make sure the medication works properly. 

But you may want to limit certain foods to reduce the risk of side effects. Bactrim can cause nausea or vomiting. If eating acidic foods bothers your stomach, avoid them while taking Bactrim.    

2. Alcohol

It’s never a great idea to drink alcohol when you’re taking antibiotics. Most antibiotics, including Bactrim, can cause nausea or diarrhea. Adding alcohol to the mix can worsen that side effect.  

In addition, Bactrim may interfere with how the body processes alcohol, leading to high levels of acetaldehyde in the blood. This can lead to a serious condition called a disulfiram-like reaction. 

Signs of a disulfiram-like reaction include:

• Sweating

• Flushing

• Fast heart rate

• Nausea and vomiting

Fortunately, the risk of this reaction may be lower than once thought. A recent review found only weak evidence to support the link between Bactrim, alcohol, and the disulfiram-like reaction. But most healthcare professionals still advise people to avoid alcohol while taking Bactrim.     

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3. Bananas and other potassium-rich foods

Potassium is an important electrolyte. The trimethoprim component of Bactrim interferes with how the kidney eliminates potassium. That can raise potassium levels in the blood. 

For most people taking Bactrim, this won’t cause any problems. But if you have kidney disease or take other medicines that also raise potassium levels, you may be at risk for developing high potassium levels (hyperkalemia). Hyperkalemia can be dangerous.

Avoid taking in extra potassium by limiting high-potassium foods, such as:

• Apricots

• Avocados

• Bananas

• Beans

• Beets

• Leafy greens like spinach and kale

• Sweet potatoes

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Talk with your healthcare team if you have kidney problems or take medications that increase your potassium before starting Bactrim.

4. Caffeine

Food and drinks with caffeine don’t interact strongly with Bactrim. But that doesn’t necessarily mean that you should drink a lot of caffeine when you’re taking Bactrim. 

Caffeine has a diuretic effect, which means it can make you pee more often. Normally, caffeine doesn’t cause dehydration. So most people can still enjoy their usual tea or coffee drinks while taking Bactrim. But if you’re dehydrated because you have a fever and you aren’t eating much, then you should focus on noncaffeinated drinks to help you stay hydrated instead. 

What else can you do to make it easier to take sulfamethoxazole / trimethoprim (Bactrim)?

Apart from avoiding or limiting certain foods and drinks, there are other things you can do to make it easier to take Bactrim and reduce the risk of side effects.

Take Bactrim with food 

Taking Bactrim with a meal or snack may reduce your risk of an upset stomach. If you do feel nauseated, try eating small, frequent meals. Pick bland, starchy foods like toast, crackers, and applesauce. 

Stay hydrated 

Take Bactrim with a full glass of water. Bactrim can cause development of crystals in the urine. These crystals can lead to kidney injury. Staying hydrated reduces the risk of crystal formation.

Eat foods to support a healthy gut 

Any antibiotic, including Bactrim, can kill off good gut bacteria. Eating probiotic foods like yogurt and pickled vegetables can help restore healthy bacteria in the gut. Whole grains, fruits, and legumes are a good source of prebiotics. Prebiotics can also help keep your gut microbiome healthy. 

Avoid foods that upset your stomach 

If Bactrim upsets your stomach, it’s best to stay away from foods that can worsen that side effect. For many people, that means limiting spicy or greasy foods.

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Written by:

Brian Clista, MD

Dr. Clista is a board-certified pediatrician who works in private practice in Pittsburgh, Pennsylvania. He previously served as a National Health Service Corporation Scholar in the inner city of Pittsburgh for 11 years.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

Reviewed by:

Christine Giordano, MD

Christine Giordano, MD, is board-certified in general internal medicine. She received her medical degree from Rutgers New Jersey Medical School and completed residency at Thomas Jefferson University.

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