5 foods to eat while on antibiotics

Antibiotics treat infections by targeting bacteria. They kill the bad bacteria causing the infection and stop them from multiplying.

However, in the process, they can kill other harmless bacteria. This can disrupt the natural balance of bacteria in the gut, which is known as the gut microbiome or gut flora.

Antibiotics can affect the diversity and balance of bacteria in your gut, which are essential for healthy digestion.

Silvia Fonda Nutritionist

You need a healthy gut flora for good digestion. A healthy gut flora helps to fend off harmful microorganisms, digest dietary fibre (which your body can’t do on its own) and absorb essential vitamins from your diet.

When antibiotics disrupt this gut flora, it causes digestive side effects. Common digestive side effects of antibiotics include:

• diarrhoea
• feeling or being sick
• stomach pain
• feeling bloated

These side effects are mild and, in most cases, go away on their own. However, it can make you feel unwell for a short time.

One way to help relieve these symptoms naturally is to change your diet. This is because your diet can impact gut bacteria, gut inflammation as well as your overall digestive health.

Increasing the intake of certain foods can help boost your gut flora and manage side effects. Here are 5 foods that do just that.

1. Probiotic-rich foods

Probiotics are live microorganisms such as bacteria and yeast that are common in certain foods or available as supplements.

Consuming supplements or foods rich in probiotics helps to improve and restore the gut flora while taking antibiotics, which can help to prevent and reduce side effects.

• non-dairy yoghurts with live cultures
• sauerkraut
• kimchi
• miso
• kombucha

You should prioritise non-dairy probiotics. This is because dairy products like milk and cheese may reduce the effectiveness of antibiotics.

When buying probiotics, you should always check the labels. Check what it contains so you can get maximum benefits for your gut flora from your diet. Look for names of good bacteria like Lactobacillus and Bifidobacterium.

2. Prebiotic foods

While probiotics are the good bacteria, prebiotics help to feed these good bacteria.

When you consume prebiotics, the bacteria in your gut break them down for energy. This will help to increase their chance of survival in the gut. They also produce by-products that can help with digestion.

Prebiotic foods are foods rich in fibre. However, not all fibres are prebiotics. Some foods naturally high in prebiotics include:

• almonds
• bananas
• whole grains wheat (e.g. pasta, bread, oats, quinoa or breakfast cereals)
• whole grain corn (e.g. corn on or off the cob, polenta, tortillas or tortilla chips)
• flax seeds
• soy (e.g. soy milk, tofu or miso)
• certain vegetables (e.g. cabbage, artichokes, onion, peas, aubergine, artichoke or asparagus)
• raw leafy greens (e.g. leeks or chicory)
• legumes (e.g. beans and peas)
• honey or agave

These foods are also high in other essential nutrients like vitamins and minerals that are key for a healthy diet.

3. Fibre-rich foods

Fibre is an essential nutrient for healthy digestion.

Dietary fibre is the part of plants you eat that is not digested in the small intestine. Instead, it is broken down by the bacteria in your large intestine.

This helps to reduce the effects of antibiotics as it can increase the amounts of beneficial bacteria as well as improve the diversity of microorganisms in the gut.

Fibre is an important nutrient, not just for antibiotic side effects, but also for your overall digestive health.

Silvia Fonda Nutritionist

Fibre is also important for your overall digestive health. Eating more fibre helps to:

• improve constipation
• boost your immunity
• reduce inflammation in your gut

The association of UK dietitians (the BDA) recommends adults need to eat around 30 g of dietary fibre every day to experience health benefits.

The best sources of dietary fibre include:

• cereals and carbohydrates (e.g. shredded whole wheat, oats or wholemeal bread)
• fruits like figs or strawberries
• vegetables like parsnips and broccoli
• legumes like peas and beans
• nuts like almonds and peanuts
• seeds like sunflower or sesame seeds

You can make simple switches to help boost your fibre. You can switch out the bread for your sandwiches or add some fruit to your breakfast cereal or your porridge (oatmeal).

4. Hydrating foods and fluids

When taking antibiotics, it’s important that you stay hydrated.

Side effects of antibiotics, such as vomiting and diarrhoea, can cause dehydration when you lose too many fluids. This could be a serious health problem if not treated.

If you are dehydrated, you may notice symptoms such as:

• feeling thirsty
• dark yellow or strong-smelling pee
• peeing less often than usual
• feeling dizzy or lightheaded
• feeling tired
• dry mouth, lips and tongue

The way to prevent dehydration is to drink plenty of fluids. This can be in actual beverages or foods that have a high liquid content, such as soups and certain fruits and vegetables.

5. Foods high in antioxidants

Another beneficial food compound is antioxidants.

The role of antioxidants is to prevent oxidation, a chemical reaction that produces unstable molecules called free radicals. High levels of free radicals cause oxidative stress, which can cause certain health problems.

Research suggests that oxidative stress can occur in the gut and affect the gut microbiome. Some evidence from mouse studies suggests that consuming antioxidants can reverse this effect. This means it can help prevent digestive side effects whilst on antibiotics.

Foods rich in antioxidants have multiple health benefits, as well as gut health. Many chronic conditions have been linked to oxidative stress, including certain cancers.

Good sources of antioxidants include:

• fruits (e.g. cranberries, red grapes, peaches, raspberries, cherries, apples and pears)
• dried fruits (e.g. dates and raisins)
• vegetables (e.g. avocados, beetroot, radish, lettuce, sweet potatoes, squash and pumpkin)
• spices & herbs (e.g. cinnamon, oregano, turmeric, cumin, parsley, basil and curry powder)
• nuts (e.g. walnuts, hazelnuts, pistachio nuts, cashews and macadamia nuts)
• fruit juices (e.g. apple juice, tomato juice and pomegranate juice)
• tea (e.g. green tea and black tea)

These foods are also rich in essential nutrients and are therefore essential as part of a healthy diet.

1. Alcohol

It’s best to avoid drinking alcohol when you’re on antibiotics. This is because the effects of alcohol could make you feel unwell and dehydrate you, which can make the side effects of antibiotics worse should you experience them.

But with most common antibiotics, it is generally safe to drink small amounts of alcohol. Always consult your doctor or pharmacist if you are not sure.

Some specific antibiotics, however, you should not drink any alcohol with as the medicine is more affected. See specific interactions below.

Metronidazole & Tinidazole

When taken with alcohol, these antibiotics can cause side effects such as:

• feeling and being sick
• stomach pain
• hot flushes
• headaches
• feeling dizzy
• feeling drowsy

If you take metronidazole, you need to wait 48 hours after you have finished treatment before drinking any alcohol. For tinidazole, you need to wait 72 hours.

Linezolid

Alcohol can increase your blood pressure if you are taking Linezolid.

This includes fermented alcoholic drinks like:

• sherry
• wine
• draught beer
• lager

You should not drink more than one alcoholic drink whilst on Linezolid. If you have high blood pressure, you should not drink any alcohol until you have finished treatment.

Doxycyline

Doxycycline is a very widely used antibiotic. It is prescribed to treat STIs like chlamydia, lung infections, skin conditions like acne or rosacea, and to prevent malaria.

If you drink alcohol on Doxycycline, it may reduce the effects of the antibiotic and affect your treatment.

So, you should wait until you finish treatment before you drink any alcohol.

2. Dairy and high-calcium products

Dairy products that are high in calcium can affect the absorption of certain antibiotics like tetracyclines (e.g. doxycycline) and fluoroquinolones (e.g. ciprofloxacin).

The medicine can bind to the calcium, which prevents it from being absorbed by the body. This can reduce the effectiveness of the medicine.

High-calcium and dairy foods include:

• milk
• cheese
• dairy yoghurt
• tofu
• tinned fish
• custard

You should wait 2 hours after consuming one of these products before taking antibiotics. Then, you should wait 2 hours after taking antibiotics before consuming dairy or a high-calcium food.

If you have had a small amount of calcium, like milk in your tea, it should be okay.

3. Processed foods

You should avoid eating processed foods while on antibiotics. This includes foods high in fat and sugar, such as:

• fast food and takeaways
• chocolate, cakes, biscuits and pastries
• savoury snacks like crisps, sausage rolls or pies
• processed meats like bacon, ham and sausages
• sugary drinks

Ultra-processed foods do not contain diverse or sufficient amounts of macro- and micronutrients. Your gut needs these nutrients to maintain a balance of microorganisms.

A diet high in processed foods has also been shown by research to cause gut inflammation. Other studies have linked it to chronic gut diseases such as irritable bowel syndrome, inflammatory bowel disease and even bowel cancer.

So, eating these foods in moderation while on antibiotics will help keep your gut microbiome healthy and help prevent antibiotic side effects.

As well as your diet, there are other things you can do to help you get the most out of your antibiotics and feel better.

You must take your antibiotics exactly as instructed. If you take them wrong or when you don’t need them, this can cause your body to build up resistance to them. This can be serious and can make treating future infections a lot harder.

Dr. Caroline Fontana Lead Prescribing Doctor

Lifestyle advice for antibiotic users

Tips and advice for people taking antibiotics

Take antibiotics exactly as prescribed

• You should take the entire course of antibiotics.
• Do not stop taking them sooner, even if you start to feel better.
• This ensures the medicine works properly and prevents your body from becoming resistant to those antibiotics over time.

Take antibiotics only when you need them

• Only take antibiotics when your doctor has advised you to do so.
• If you have a viral infection like a common cold or flu, you do not need to take antibiotics.
• Do not take antibiotics from someone else or spare antibiotics if you have any left over from previous treatment.
• Taking them when you don’t need them can cause antibiotic resistance.

Rest

• Your body is fighting off an infection, so make sure you rest as much as possible.
• Listen to your body and don’t do too much too soon - allow yourself time to recover.

Monitor side effects

• Most common side effects are mild and should go away on their own.
• However, you should check in on how you are feeling and read the patient information leaflet to learn about potential side effects.
• Speak to your pharmacist or doctor if you experience any worrying or ongoing side effects.

Your doctor may need to investigate your symptoms and to see if there is an underlying cause.