New Straits Times

Beware of food and medication interactions

The efficacy of certain medications will reduce depending on the food consumption that follows after, claims expert. This is what you should watch out for

PUBLISHED : Tuesday, 21 March, 2017, 4:30pm
UPDATED : Tuesday, 21 March, 2017, 4:30pm

By Indra Balaratnam

When you take oral medication to treat an illness or swallow a nutritional supplement, they end up being digested together with the food and drinks you consume.

For the most part, many of us take these without giving much thought to the fact that they may interact with each other.

Certain food may affect the absorption of some medicines. This is important to know so that you do not jeopardise your treatment.

Taking some of these food together with certain medications may lessen the effectiveness of the latter or cause complications.

Let’s take a look at some common food and medication interactions.


Doctors prescribe ACE inhibitor medication and diuretics to lower blood pressure, reduce water retention and treat heart failure.

These medications may increase the amount of potassium in your body. Due to this, do not take excessive amount of food that are high in potassium such as bananas, leafy green vegetables and oranges if you have been prescribed these medications.


Warfarin is a blood-thinning medication. Food that is high in vitamin K, such as leafy green vegetables, kale, cabbage, broccoli, spinach and Brussels sprouts, reduce warfarin’s anti-bloodclotting function.


If you are taking tetracycline, a type of antibiotics, be aware that calcium will lessen the effectiveness of this medication.

Calcium-rich foods such as milk, yogurt, cheese and cream should not be taken together with this antibiotic. Don’t forget calcium-fortified foods, beverages and supplements as well.

Apart from calcium, iron tablets and aluminium in antacids can reduce the absorption capacity of tetracycline.

The usual instruction is to take tetracycline one hour before or two hours after a meal.


Black liquorice, which is used to make the popular black cultured candy, contains a component called glycyrrhizin. This compound interacts with digoxin, which is prescribed to patients with abnormal heart rhythm and heart failure.

Apart from digoxin, black liquorice should be avoided if you are taking medication for blood thinning, pain relievers, birth control pills and high blood pressure.

Be careful about taking natural liquorice root supplements, which have the same interaction with these medications.


Tyramine is an amino acid that is found in a variety of food such as chocolate, smoked or fermented meats, processed meats, fermented soya products and aged cheese.

Eating too much tyramine foods is not advisable for people taking medications for Parkinson’s disease and depression (monoamine oxidase inhibitors, also known as MAOIs).


A high-fibre diet can decrease the absorption of antidepressant medications such as amitriptyline, causing it to be less effective.

High-fibre food that is also high in phytate compounds such as oats and wheat bran should also not be taken together with the heart medication digoxin as they lessen the absorption of the medication.


This interesting-sounding word is a natural compound found in grapefruit and its relatives, the pomelo and Seville oranges.

Avoid these fruits if you are taking cholesterol-lowering medications, antihistamines, high blood pressure medications, thyroid replacement medications and a type of cough medicine that contains dextromethorphan.

The compound furanocoumarins increases the absorption of these medicines, which can cause uncertainty in how your body metabolises them.


Taking ginseng when you are on nonsteroidal anti-inflammatory medicines such as ibuprofen, MAO inhibitors, aspirin and blood thinners like warfarin can cause undesirable side effects ranging from bleeding and headaches to nervousness and problems sleeping.


It is always a good idea to generally avoid alcohol if you are taking any form of prescription medication.

The impact of alcohol interaction with certain medications can be particularly dangerous — so be prudent.


Make it a habit to always read the pamphlet that comes with the medication you purchase. The pamphlet will tell you important features about the medication that you should be aware of.

Sometimes, the medication you receive from your doctor or hospital pharmacy does not come in the original packaging with the pamphlet. It’s usually in a small white plastic envelope or container with instructions to either take it before or after food.

I would highly encourage you to be a more proactive patient and double check with your doctor, pharmacist or dietitian if there are any foods or lifestyle practices you should avoid when taking the medication.

Write down what they tell you. If in doubt, you can also always call the company that manufactures the medication to get more information.

*Indra Balaratnam is a consultant dietitian who believes in simple, practical ways to eating well and living healthy.

Beware of food and medication interactions