Doctor Answers: 8 Foods to Avoid When Taking Sulfamethoxazole / Trimethoprim

If you’ve recently been prescribed sulfamethoxazole combined with trimethoprim (commonly sold under the brand name Bactrim), it’s important to understand how certain foods can affect the absorption and effectiveness of this antibiotic. But what foods to avoid when taking Sulfamethoxazole / Trimethoprim?

We spoke with Dr. Sony Sherpa, a practicing integrative medicine physician, who provided in-depth insights into dietary interactions and gave practical advice for patients using this medication. Dr. Sherpa’s answers are based on current clinical knowledge and research, and the article has been medically reviewed for accuracy and completeness.

Q: What Foods Should I Avoid when Taking Bactrim?

Dr. Sherpa answers: When using antibiotics such as sulfamethoxazole/trimethoprim, you should avoid certain foods as they may impact their absorption and effectiveness.

1) Alcohol

Bactrim can prevent the liver from breaking down alcohol. This may result in a “disulfiram-like” interaction. Sulfamethoxazole/trimethoprim may interfere with acetaldehyde dehydrogenase, a chemical that aids in the breakdown of alcohol so that your body can metabolize it. This reaction is comparable to that generated by the drug disulfiram (Antabuse), which is used to prevent alcoholics from drinking.

Avoid all foods or beverages containing alcohol while taking Bactrim because they can cause symptoms such as severe nausea and vomiting, shortness of breath, facial flushing, irregular heartbeat, and headache.

Foods cooked with alcohol may retain an unexpected amount of alcohol, so avoid them when taking Bactrim. When you add alcohol to a sauce and remove it from the heat, 85 percent of the alcohol content is retained.

2) Potassium-Rich Foods

Bactrim may raise potassium levels in people who have poor kidney function. If you have kidney problems, see your doctor about whether you should avoid potassium-rich salt replacements as well as potassium-rich foods such as:

• Cooked spinach
• Chocolate
• Bananas
• Milk
• Pumpkin
• Potatoes

3) Food Containing Propylene Glycol

When taking medications like sulfamethoxazole and trimethoprim through injection, it’s essential to avoid consuming foods or beverages that contain propylene glycol. Propylene glycol is a common chemical compound found in various processed foods, soft drinks, and even pharmaceutical products.

When combined with certain medications, propylene glycol can potentially affect the body’s metabolism and clearance of the medication, leading to adverse effects or decreased effectiveness. In the case of sulfamethoxazole and trimethoprim, the presence of propylene glycol could alter the way the medication is processed in the body.

As a result, it’s advised to abstain from consuming foods, beverages, and pharmaceutical products that contain propylene glycol while undergoing treatment with medications like sulfamethoxazole and trimethoprim through injection.

4) Highly Acidic Foods

Highly acidic foods like citrus fruits, tomatoes, and sodas should be avoided while taking sulfamethoxazole and trimethoprim. These foods can significantly impact the absorption of antibiotics. The acidity in these items can alter the pH of your stomach and digestive tract, potentially affecting the effectiveness of the medication.

By avoiding these acidic foods, you can help ensure that the antibiotics are properly absorbed and can work optimally in combating infections.

5) Calcium-Containing Foods

When on a sulfamethoxazole and trimethoprim regimen, excessive consumption of calcium-rich foods can hinder the absorption of the antibiotics. Opting for fermented dairy products instead of high-calcium options can be a workaround to ensure that the medication is effectively absorbed.

6) Fortified Foods

Similar to naturally calcium-rich foods, fortified foods with added calcium content can also interfere with the absorption of sulfamethoxazole and trimethoprim. The additional calcium content in fortified foods exacerbates the competition for absorption in the digestive tract.

Steering clear of these fortified options is recommended to ensure that the antibiotics are fully absorbed and can exert their desired effects.

7) Grapefruit and Its Derivatives

Grapefruit and products derived from it, such as grapefruit juice, should be avoided while taking sulfamethoxazole and trimethoprim. Grapefruit contains compounds called furanocoumarins that can inhibit enzymes responsible for drug metabolism in the liver.

This can lead to elevated levels of the antibiotics in your bloodstream, potentially causing adverse effects or altering the medication’s effectiveness. By avoiding grapefruit and its derivatives, you prevent unwanted interactions and ensure the antibiotics work as intended.

8) Caffeine

Caffeine is a stimulant that can have effects on blood pressure, restlessness, and sleep patterns. When combined with sulfamethoxazole and trimethoprim, which can also lead to anxiety or sleep disturbances as side effects, these effects might be amplified. While caffeine itself doesn’t directly interact with the medication, the combined impact on your body can exacerbate discomfort. Avoiding caffeine can help mitigate potential additive effects and allow your body to cope better with any medication-related symptoms.

Q: What Foods are Recommended while on Sulfamethoxazole/Trimethoprim?

Dr. Sherpa answers: Here are some foods that are recommended for consumption while taking Bactrim.

1) Prebiotics

Prebiotic meals are beneficial for gut microorganisms and are commonly found in foods high in fiber. Examples of prebiotic foods include:

• Kefir
• Chicory roots
• Garlic
• Barley
• Bananas
• Asparagus
• Yogurt
• Onion
• Apple
• Oats

2) Probiotics

Probiotics contribute to overall health by supporting the maintenance of healthy microbes. Probiotic foods include:

• Yogurt
• Kefir
• Tempeh
• Miso
• Milk
• Kimchi

3) Fermented Foods

Fermented foods containing lactobacilli help restore gut microbiota. Common examples of fermented foods are:

• Cheese
• Cultured milk
• Yogurt
• Sauerkraut
• Kombucha
• Fermented soybean milk
• Kimchi

4) High Fiber Foods

Fiber-rich foods play a role in promoting the growth of healthy gut microbes. Some examples of high-fiber foods are:

• Peas
• Nuts
• Whole grains
• Beans
• Bananas
• Seeds
• Lentils
• Broccoli
• Apples
• Avocados

Q: What are Other Drug Interactions to Know About?

Dr. Sherpa answers: Here are three interactions involving sulfamethoxazole/trimethoprim that you should be aware of:

Warfarin

Bactrim interacts with warfarin, a commonly prescribed blood thinner. When taken together, Bactrim can intensify the blood-thinning effects of warfarin. This may lead to excessive thinning of the blood, increasing the risk of bleeding or bruising.

Using these two medications concurrently might necessitate more frequent blood tests. It’s also advisable to explore alternative antibiotics that do not interact with warfarin. However, if Bactrim is necessary for your condition, your doctor might consider adjusting your warfarin dosage.

Certain Diabetes Medication

Sulfamethoxazole/trimethoprim can interact with some oral type 2 diabetes medications. Bactrim has the potential to elevate their levels in your body. This elevation can lead to dangerously low blood sugar levels, triggering symptoms such as shivering, dizziness, and even confusion. Severe complications can arise if blood sugar levels drop significantly and are not promptly addressed.

Q: Should Bactrim be Taken with Food?

Dr. Sherpa answers: You can take sulfamethoxazole/trimethoprim with or without food. Take this medication by mouth with a full glass of water, as instructed by your doctor. If you experience stomach upset, take it with food or milk.

Q: What are the Side Effects Of Sulfamethoxazole/Trimethoprim?

Dr. Sherpa answers: Common side effects may include:

• Nausea
• Vomiting
• Loss of appetite
• Skin rash

Trimethoprim and sulfamethoxazole can have serious adverse effects. If you develop any of the following symptoms, contact your doctor right away:

• Severe stomach ache, watery or bloody diarrhea (even if it happens months after your previous dose)
• Yellow-colored eyes or skin
• Any type of skin rash, no matter how mild
• Increased or diminished urination
• New or unusual joint pain
• A seizure
• Increased thirst, dry mouth, and fruity breath
• Cough that is new or increasing
• Fever
• Breathing difficulties

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Key FAQs on Foods to Avoid while Taking Bactrim

Q: Can Bactrim affect hydration or electrolyte balance?

Dr. Sherpa answers: Yes, Bactrim can affect both hydration status and electrolyte levels. A well-known side effect of Bactrim is hyperkalemia, in which the levels of potassium are significantly raised. This is more common in those with kidney issues or in those taking medications like spironolactone, which is a potassium-sparing diuretic, and other medications like ACE inhibitors. Some symptoms of hyperkalemia can include fatigue, muscle weakness, arrhythmia, or even cardiac arrest in severe cases. 

Bactrim may also cause gastrointestinal side effects like nausea, vomiting, and diarrhea, which increases the risk of dehydration. Therefore, it is important to take adequate fluids while you are on this antibiotic. You should also avoid taking foods containing high levels of potassium, such as bananas, leafy green vegetables, and oranges. 

Q: Should I avoid sun exposure when taking sulfamethoxazole/trimethoprim?

Dr. Sherpa answers:It is important to be cautious with sun exposure when you are on Bactrim. This is because one of the known side effects of this medication is photosensitivity, which makes your skin more sensitive to ultraviolet (UV) radiation. Even a short amount of time spent under the sun may cause severe sunburn, redness, blistering, or rash.  

Photosensitivity reactions may occur rapidly, sometimes even within minutes of exposure to sunlight, and may take several days to resolve. Such effects are not limited just to direct sunlight but can also occur when exposed to UV rays reflected off surfaces such as glass, snow, or water. Applying adequate sunscreen with an SPF of at least 30 and reapplying it frequently, especially after swimming or sweating, can prevent severe reactions.

Q: Are there any herbal supplements that interfere with Bactrim?

Dr. Sherpa answers: Taking herbal supplements together with Bactrim can do more harm than good. For instance, St. John’s Wort may affect the liver enzymes involved in the metabolism of the drug, reducing its effectiveness. Supplements such as echinacea or licorice root may also affect kidney function, and therefore, should be used cautiously with Bactrim. It is important to consult with a healthcare provider before taking any herbal supplements while on Bactrim. 

Furthermore, supplements containing garlic and ginseng may also increase the risk of bleeding. It may exacerbate the effects of Bactrim on blood sugar levels, especially in diabetics. Some herbal supplements also have diuretic-like effects, so they should be taken with caution in those with chronic kidney disease. 

Q: Can I take antacids or digestive enzymes while on Bactrim?

Dr. Sherpa answers: Yes, it is safe to take antacids or digestive enzymes while on Bactrim, but it is best to space them out. This is because some antacids, especially those that contain aluminum or magnesium, may affect the absorption of certain medications. It is generally safe to take Bactrim at least 1 or 2 hours before or after antacids, but it is best to exercise caution with continued or prolonged intake. as no specific studies have looked at the interactions between digestive enzymes and Bactrim. 

Additionally, it’s important to pay attention to how your body responds when combining these supplements with antibiotics. If you experience increased stomach discomfort, changes in bowel habits, or signs of reduced effectiveness of Bactrim (such as persistent fever or worsening symptoms), consult your doctor. While short-term use of digestive enzymes is unlikely to interfere with Bactrim’s function, maintaining open communication with your healthcare provider can help ensure safe and effective treatment.

Q: How long after finishing Bactrim can I resume a normal diet?

Dr. Sherpa answers: After finishing a course of Bactrim, you can resume your normal diet immediately. But you still need a clearance from your doctor in case you are a special case. Long-term dietary restrictions are not required with Bactrim. But some healthcare providers may advise avoiding foods containing high levels of potassium, such as bananas, oranges, and leafy green vegetables. This is because Bactrim can further increase the levels of potassium in the blood. You may also need to avoid or limit alcohol intake as it increases the risk of gastrointestinal upset or rare reactions like disulfiram-like effects. 

Some people experience nausea and loss of appetite with particular foods while on Bactrim. After finishing Bactrim, you can reintroduce these items into your diet gradually. This allows your body and digestive system to adjust and also helps you assess how well your body is responding. If you have persistent side effects, it is important to consult your prescribing doctor.

Conclusion

If you are on sulfamethoxazole/trimethoprim or know someone who is, you need to know certain dietary restrictions and foods to avoid. Understanding these dietary limits will help you make informed decisions and get the most out of your treatment. When taking sulfamethoxazole and trimethoprim, it is best to avoid high-calcium diets, very acidic foods, citrus fruits like grapefruit and orange, and alcohol.

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