​​The next time you try to take your medicine with anything other than water, stop: you might be doing more harm than good (besides making your medicine ineffective). 

Follow Instructions When Taking Your Medication

The fundamental step to take with all medication is to follow usage instructions on the label and advice given to you by your doctor or pharmacist. Having a proper understanding of drug-food interactions – how various medicines are affected by different kinds of food and drink – will help you avoid common pitfalls and ensure your medicine works effectively. 

Drug-food interactions can occur with both prescription medication as well as over-the-counter medication. Let us now explore some common interactions between drugs, food and drink.

​Food-Drug Interactions

Drugs to be consumed WITHOUT food

When taken together at about the same time, some foods can affect the absorption rate of some medicines by your body. Such medicines should be consumed on an empty stomach, between 30 minutes to one hour before – or two hours after – a meal. Examples of these medications include:​ 

  • ​​​​​​Antibiotics such as cloxacillin, penicillin V and rifampicin
  • Thyroid replacement medication such as levothyroxine
  • Medicine to treat osteoporosis such as alendronate and risedronate​

​Drugs to be consumed WITH food 

On the other hand, certain medicines can lead to an upset stomach if taken without food. These medicines should therefore be taken with or shortly after food intake. Examples of these medications include: 

  • ​​Those that reduce the risk of clotting or stroke, such as aspirin and clopidogrel
  • Oral steroids such as prednisolone, hydrocortisone and dexamethasone
  • Painkillers such as ibuprofen, diclofenac and tramadol​

Drugs NOT to be taken with dairy products 

Some medicines should not be taken at the same time as dairy products, such as milk, cheese and yoghurt. 

One should also pay close attention to food containing calcium, magnesium and/or iron as well since they can affect the efficacy of such medicine. These medicines should be taken at least two hours after consuming dairy products or food containing the above mentioned-minerals. Examples of these include: 

  • ​​Antibiotics such as ciprofloxacin and doxycycline
  • Thyroid replacement medication such as levothyroxine
  • Medication to treat osteoporosis such as alendronate and risedronate​ 

Tyramine and Antidepressants

Food products rich in tyramine such as alcohol, avocados and soy sauce should be avoided if you are taking certain antidepressants such as moclobemide or linezolid (a form of antibiotic). This is because generally, antidepressants block an enzyme called monoamine oxidase, which breaks down excess tyramine in the body. Blocking this enzyme helps relieve depression. However, tyramine can quickly reach dangerous levels if you eat foods high in tyramine, which may cause a spike in blood pressure and require emergency treatment.​ 

​Fluid-Drug Interactions 

It is common knowledge that oral medicines should be taken with a full glass of water. But what if water is not available? We clue you in on which fluids are a definite no-no when taking with medication. 

Alcohol and Medicine

Generally, please avoid alcohol when under medication because alcohol may increase the sedative effect of medicines. So, there is a good reason to avoid alcohol for your own personal safety!

Caffeine and Medicine

Found commonly in tea, coffee and chocolate, high caffeine intake (more than five cups of coffee in a day) can affect some medicines. Do try to limit caffeine consumption when taking the following medicines: 

  • ​Medicines that treat respiratory conditions such as salbutamol, fenoterol and theophylline
  • Relaxants or medicines that induce sleep such as diazepam, lorazepam and zolpidem 

Grapefruit Juice and Medicine

While other fruit juices are safe to consume alongside medicines, please pay careful, special attention to grapefruit juice, as it can affect how certain medicines are cleared from the body. 

For example, if you drink a lot of grapefruit juice while taking certain statin drugs to lower cholesterol, too much of the drug may stay in your body, increasing your risk for liver damage and muscle breakdown that can lead to kidney failure. 

Medicines that you should not consume with grapefruit juice include:​

  • ​​​Cholesterol-lowering medications such as simvastatin, atorvastatin and lovastatin
  • Medicines that treat heart conditions such as nifedipine, amlodipine, verapamil and diltiazem
  • Medications for the nervous system such as ciclosporin and tacrolimus

Traditional Chinese Medicine (TCM) with Prescribed Drugs 

In general, it is good practice to check with your doctor or pharmacist if it is ok to take particular TCM along with drugs that you have been prescribed, as some interactions between TCM and western drugs can lead to certain, unexpected interactions that could be harmful. 

Always consult your doctor if you are taking TCM.​

Download the “Of Drugs, Food and Drink (PDF)”.

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