4 foods to avoid while taking Bactrim

In this article:

• How Bactrim works
• Bactrim foods to avoid
• Foods to prioritize
• Gastrointestinal side effects

In this article

• How Bactrim works
• Bactrim foods to avoid
• Foods to prioritize
• Gastrointestinal side effects

If you have a stubborn bacterial infection, your healthcare provider may prescribe a potent antibiotic like the brand-name medication Bactrim. Bactrim (sulfamethoxazole-trimethoprim), which contains the same active ingredients as Septra, is a sulfonamide antibiotic commonly used to treat urinary tract infections, traveler’s diarrhea, middle ear infections, bronchitis, and severe forms of pneumonia known as pneumocystis jirovecii and pneumocystis carinii pneumonia.

While taking Bactrim, it is generally advised to avoid acidic foods, alcohol, potassium-rich foods, and caffeine, to ensure optimal effectiveness of the medication. Here’s what to know if you’re taking this Rx.

How Bactrim works

Antibiotics work in one of two ways: killing bacteria (bactericidal) or inhibiting its growth (bacteriostatic), says David Cutler, MD, a board-certified family medicine physician at Providence Saint John’s Health Center in Santa Monica, CA. He says Bactrim works by “arresting the development” of bacteria so that it’s unable to multiply and survive—inhibiting enzymes that it needs to function.

“Sulfamethoxazole and trimethoprim work together to inhibit bacterial folate synthesis, a process required for bacterial growth and replication,” says Michael Chichak, MD, a general practitioner and Medical Director at MEDvidi. Sulfamethoxazole interferes with the bacterial synthesis of folic acid, which is essential for nucleic acid production (the DNA in bacteria). At the same time, trimethoprim further blocks a different step in the same pathway. This dual action makes Bactrim effective against a wide range of gram-positive and gram-negative bacteria.

According to Dr. Chichak, Bactrim begins to work within a few hours of the first dose. Still, the time required to clear the infection varies according to the condition being treated and the severity of the infection. While you may start to see improvement within 48 to 72 hours, it’s crucial to complete the full course of antibiotics as prescribed to ensure the infection is fully eradicated.

4 foods to avoid with Bactrim

Bactrim may be affected by certain foods, which could either diminish its effectiveness or exacerbate side effects. Here’s a list of foods to be cautious about while taking Bactrim.

1. Acidic foods

It’s not necessary to eliminate acidic foods with Bactrim unless it is upsetting your stomach, according to Dr. Cutler. This antibiotic is known for gastrointestinal side effects like nausea, vomiting, and indigestion, which could be worsened by high-acid foods. If you’re experiencing stomach problems with sulfamethoxazole and trimethoprim, avoiding citrus fruits like grapefruit and other acidic foods could help.

2. Alcohol

No matter what ails you, it’s best to stay alcohol-free when you’re fighting an infection, whether bacterial or viral. That’s because alcohol weakens your immune system, and you want it to be in full working order while you recover. But that’s not all.

In addition to worsening GI side effects, certain antibiotics, including metronidazole, tinidazole, and sulfamethoxazole-trimethoprim, should never be mixed with alcohol. These meds interfere with your liver’s ability to break it down. Dr. Chichak says the combination can lead to what’s known as a “disulfiram-like reaction,” which causes serious side effects like headache, nausea, vomiting, fast heart rate, and flushing.

3. Potassium-rich foods

“Bactrim has been shown to raise potassium levels in some people, particularly those with kidney problems,” says Dr. Chichak. According to research, trimethoprim can interfere with potassium secretion in the kidneys. Consuming too many potassium-rich foods, like bananas, oranges, and spinach, may cause dangerously high potassium levels (hyperkalemia), causing serious symptoms such as muscle weakness, trouble breathing, severe abdominal pain, and heart rhythm disturbances, says Dr. Chichak.

4. Caffeine

There’s no explicit reason to avoid caffeine on Bactrim, but it is a diuretic that can lead to dehydration in large quantities. Dr. Chichak recommends limiting coffee, tea, and energy drinks while taking the medication.

In addition to the above foods, Dr Chichak recommends avoiding foods or beverages that may aggravate gastrointestinal discomfort, such as spicy, greasy, or fried foods. He says high-sugar or processed foods may also harm your immune system and the healing process. If you’re taking any over-the-counter or prescription drugs or dietary supplements, it’s best to consult your healthcare provider for medical advice, as some may interact with Bactrim.

 What should you eat while taking Bactrim?

“Bactrim does not require any specific food to enhance absorption, as it is absorbed well on an empty stomach,” says Dr. Chichak. However, if it causes nausea or stomach discomfort, he recommends taking it with a light meal (such as toast, eggs, or applesauce) to ease symptoms without significantly impacting its effectiveness.

In addition to lean proteins, whole grains, fruits, and vegetables, Dr. Chichak recommends incorporating the following foods into your diet while taking Bactrim:

• Probiotic-rich foods like yogurt or kefir can help maintain gut health and prevent antibiotic-associated diarrhea.
• High-fiber foods such as oats, whole grains, and leafy greens can aid digestion.
• Hydrating foods like watermelon and cucumber, along with plenty of water, help to stay hydrated and counteract potential dehydration caused by Bactrim side effects like diarrhea.

Gastrointestinal side effects of Bactrim

Bactrim can cause gastrointestinal side effects such as nausea, vomiting, and diarrhea. These side effects may be exacerbated by the foods mentioned above, particularly acidic foods and alcohol.

Other common side effects of Bactrim include:

• Loss of appetite
• Swollen or painful tongue
• Dizziness
• Tinnitus (ringing in the ears)
• Fatigue
• Insomnia
• Skin rash
• Photosensitivity

To minimize gastrointestinal side effects, Dr. Chichak advises taking Bactrim with food and plenty of water. If you experience severe symptoms like persistent vomiting or blood in your stool, seek medical attention immediately. In rare cases, Bactrim can cause impaired kidney function, allergic reactions, thyroid issues, anemia, kidney stones, liver problems, and low blood sugar (hypoglycemia).

Bactrim is not safe for pregnant or breastfeeding individuals or those with certain medical conditions, such as kidney disease and liver disease.

The following medications are contraindicated with Bactrim:

• Diuretics
• Methotrexate
• Cyclosporine
• Indomethacin
• Pyrimethamine
• Amantadine
• Angiotensin-converting enzyme (ACE) inhibitors
• Dofetilide

The bottom line? Your dietary choices matter when you’re taking Bactrim, but there aren’t many food interactions. Avoiding acidic foods, alcohol, potassium-rich items, and caffeine while taking the medication will help minimize side effects and potential adverse reactions. And remember, it’s vital to complete your full course of antibiotics to treat your infection—doctor’s orders.