The surprising foods you can’t mix with medication

You’re probably aware of the importance of taking prescribed medications as directed by your doctor. However, what many people don’t realise is that certain foods can interact with these medications, potentially altering their effectiveness or causing adverse reactions. From grapefruit to dairy products, here’s a closer look at some common foods that you should avoid mixing with certain medications.


While grapefruit is packed with vitamins and antioxidants, it can interfere with the way your body metabolises certain medications. Compounds found in grapefruit inhibit enzymes in the intestines responsible for breaking down medications, leading to higher or lower levels of the drug in your bloodstream. 

Although scientists have known for several decades that grapefruit juice can cause too much of certain drugs in the body, more recent studies have found that the juice has the opposite effect on a few other medications.

Here are examples of some types of drugs with which grapefruit juice can interact:

Statins: medications such as atorvastatin (Lipitor), simvastatin (Zocor), and rosuvastatin (Crestor) are commonly prescribed to lower cholesterol levels. Grapefruit can interfere with the metabolism of these medications, potentially leading to higher levels of statins in the bloodstream and an increased risk of side-effects such as muscle pain or liver damage.

Calcium channel blockers: medications such as amlodipine (Norvasc), felodipine (Plendil), and nifedipine (Adalat) are used to treat high blood pressure and angina. Grapefruit juice can inhibit the metabolism of calcium channel blockers, leading to higher blood levels of the medication and an increased risk of side-effects such as dizziness, headache, and flushing.

Immunosuppressants: medications such as cyclosporine (Neoral) and tacrolimus (Prograf) are prescribed to prevent rejection of transplanted organs and to treat autoimmune diseases. Grapefruit can interfere with the metabolism of these drugs, potentially leading to higher blood levels and an increased risk of toxicity.

Some antidepressants: certain antidepressants, particularly those belonging to the selective serotonin reuptake inhibitor (SSRI) class, may interact with grapefruit. Examples include sertraline (Zoloft) and escitalopram (Lexapro). Grapefruit juice can inhibit the metabolism of these medications, leading to higher blood levels and an increased risk of side-effects such as serotonin syndrome.

Dairy products

Calcium-rich dairy products such as milk, cheese, and yoghurt are essential for bone health, but they can also interfere with the absorption of certain antibiotics and thyroid medications. The calcium in dairy can bind to these medications in the digestive tract, preventing them from being fully absorbed into the bloodstream. 

To ensure the effectiveness of antibiotics in the tetracycline class (including doxycycline and minocycline, which are prescribed to treat bacterial pneumonia and other infections) and ciprofloxacin (from the quinolone class, also prescribed for pneumonia and other infections), it’s best to take them at least two hours before or after consuming dairy products.

Leafy greens

While leafy greens such as spinach, kale, and broccoli are nutritional powerhouses, they contain high levels of vitamin K, which can interfere with blood-thinning medications such as warfarin. Vitamin K plays a crucial role in blood clotting, so consuming large amounts of leafy greens can counteract the effects of anticoagulants, leading to an increased risk of blood clots or excessive bleeding.

Tyramine-rich foods

Tyramine is a compound found in aged, fermented, and cured foods such as aged cheeses, cured meats, and certain types of beer and wine. While tyramine itself isn’t harmful, it can cause a sudden increase in blood pressure when combined with certain medications known as Monoamine oxidase inhibitors (MAOIs). MAOIs are less commonly prescribed for depression nowadays, but they are still used in treating conditions such as Parkinson’s disease. 

This interaction can lead to a dangerous condition called hypertensive crisis, characterised by severe headaches, rapid heartbeat, and even stroke.

Bananas and avocados

Angiotensin-converting-enzyme (ACE) inhibitors are a go-to for managing high blood pressure, but when combined with potassium-rich foods such as bananas, they can lead to dangerous heart arrhythmias. Other potassium-rich foods include avocados, tomatoes, and dried apricots.

It’s recommended that some ACE inhibitors, such as captopril (Capoten) be taken at least an hour before meals.

High-fibre foods 

High-fibre foods can affect the absorption of levothyroxine for thyroid issues and digoxin for heart failure. To ensure these medications work effectively, take them at least two hours before or after a high-fibre meal.

This is not an exhaustive list, and always consult your healthcare provider or pharmacist if you have any questions or concerns about potential interactions between foods and your medications.

Have you ever encountered a surprising food-drug interaction? Share your stories and tips in the comments below.

Also read: Why it’s a bad idea to mix alcohol with some medications

Disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.

Ellie Baxter
Ellie Baxter
Writer and editor with interests in travel, health, wellbeing and food. Has knowledge of marketing psychology, social media management and is a keen observer and commentator on issues facing older Australians.


  1. My Blood Pressure Medication has Both Grape Fruit and Potassium warnings on it.
    I hate Grape Fruit and have Latex Related Food Allergies, which means that I cannot eat Bananas, Avocados and a few other fruits.

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