Everything you need to know about medication interactions

Any pill that’s been prescribed is perfectly safe, right? And if someone you know has a similar condition, there’s no harm in taking the medication that was recommended for them, surely? Think again. All medication has the potential to cause significant side effects based on interactions with key lifestyle factors.

There’s a reason your doctor makes careful notes of your medical history before writing a prescription. Of course, they want to know if any previous conditions may have a bearing on how you currently feel, but it’s equally important that they find out whether you are taking any medication – even ‘innocent’ over-the-counter medicine or natural remedies – that may interact with the medication they are about to prescribe.

What’s more, drug interactions are just one factor that may influence the effect of a medication on your body, says Johan Viljoen, an experienced pharmacist and Head of Operations at Medihelp. Gender, age, and pre-existing conditions may all have an impact.

The impact of gender
Many people neglect to check the label on their prescribed medication once their pharmacist has dispensed, which is a mistake, says Johan. “You wouldn’t prescribe a pill containing the female hormone oestrogen for a man – but chances are, if it’s dispensed, he’d swallow it without checking.”

Johan adds that your medical aid is unlikely to pay for medication that is prescribed to the wrong person: “a father can’t ask his doctor to prescribe birth control on behalf of his daughter, for example.” The moral? Check your script before accepting it to ensure you are using medication appropriately.

Age: more than just a number
If you’ve got a sick child and you’ve run out of paediatric medication, it’s tempting to hand over whichever painkillers are at hand. This is an enormous mistake, Johan cautions, as not all medications have been tested for paediatric use. What’s more, not all medications are appropriate for children: you can’t give a child a sleeping tablet, for instance.

It’s important to take just as much care when medicating elderly patients, as our metabolism slows with age. That means an older individual requires a smaller dose to achieve the same effect.

Multiple medications
Does this scenario sound familiar: rather than miss deadlines because of your cold, you stock up on every over-the-counter medicine you can get your hands on? There’s no reason to worry that it might not be safe because all of these preparations are available without a script… right?

Wrong, says Johan. “People often underestimate the dosages they take when they mix medications, but it all adds up to create a significant amount of active ingredients.” Be sure to give your pharmacist a list of everything you are taking to avoid potential harm. This is especially important when using combination medicines. “Paracetamol is the active ingredient in many combination medicines, and you do not want to overdose yourself by taking more than one combination product,” he warns.

Medicine and food
It may surprise you to learn that what you have on your plate can affect how a medication acts on your body, but this is certainly the case, Johan says. “Some substances can impact how your body metabolises medication, making less of the active ingredient available and therefore decreasing its effects,” he explains. Grapefruit juice is a good example: it can interfere with the workings of certain antihistamines and anticoagulants. In contrast, eating fatty foods can improve the absorption of certain medicine.

Many medications clash with alcohol, but it’s not just the goodies inside your liquor cabinet that must be avoided. Certain foods contain alcohol too, such as vinegar. Ask your pharmacist for advice.

Medication versus medication
Here’s a common scenario: you’re feeling ill in some way, so you take a pill to address the problem. Shortly after, you experience a new symptom, so you pop another pill. Instead of feeling better, your body produces yet another new issue, so it’s back to the pharmacist for more medication.

Johan calls this a ‘therapeutic train’. “Sometimes, symptoms occur as side effects to a medication you’ve taken and are not actually the result of an illness or condition. That’s why it’s vital to keep your doctor and pharmacist informed of any medicine you take, even over-the-counter or homeopathic preparations.”

This is all the more important because certain drugs can impede the absorption of other medications or affect their action on the body. The interaction between warfarin and aspirin stands out as an example – the former is an anticoagulant, while the other thins the blood, so taking both together can increase the risk of bleeding.

“There really are three stakeholders involved every time a medicine is prescribed: the doctor, the pharmacist and the patient. Each bears a responsibility in terms of ensuring that medication is safe for the case in question,” Johan concludes.

To help you better understand this interplay we are offering a FREE webinar on about medication interactions.

Topic: Everything you need to know about medication interactions
Date: 3 April 2024
Time: 18:00

Register here: MedTalk