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Have you ever wondered how taking multiple medications daily can potentially interact when processed together in your body?

The medications we take are designed to have specific jobs (e.g. to control HIV), however a number of factors can affect and limit their optimal functioning and your health outcomes. One of these is those factors known as drug-to-drug interactions, and is primarily when the liver tries to break them down. There are a few other places where interactions can take place (e.g. the kidneys), but for today let’s concentrate on the liver.

It sounds obvious, but the majority of things that go into your body get broken down (or metabolised) by the liver. Most of what we eat and drink, the medications taken, any vitamins or herbal supplements, and any chemicals taken in from the environment, are processed by this remarkable organ…the liver.

If you are taking multiple medications regularly, you may be asking your liver to do a number of similar tasks at the same time. Medications and other substances can be broken down by one of a number of ways (pathways) in the liver. As we progressively need new and different medications to enhance our health, we also create the potential competition for their processing and breaking down and disposal.

So what is the big deal and what can happen?

Sometimes nothing, the liver may just work and get the job done. However, there are two other scenarios which potentially can affect your health outcomes.

Firstly, the liver can preferentially process (or favour) one substance or medications breakdown over another, which means that a medication is not broken down quicker than expected. This could lead to higher levels of the unprocessed medication in the body. Alternatively, one medication may be broken down quicker, leading to lower than expected medication levels in the body.

In layman’s terms, medications that are competing to be broken down can lead to too much drug (toxicity) or too little drug (sub-therapeutic levels) in your body. Medication-related side effects can occur if the levels are too high.

Conversely, low blood levels of a medication can decrease its intended effectiveness. For example, low blood levels of HIV antiretroviral medication could cause fluctuations in your HIV viral load, which over time can contribute to the development of HIV drug resistance.

Don’t fret. Manufacturers of HIV antiretroviral and other medications are always working to make their drugs safer and less susceptible to drug-to-drug interactions.

Your HIV doctor and pharmacist are always looking at the potential for these drug interactions and really want to ensure that the medications you are taking, including your HIV antiretroviral medications, work as they have been prescribed.

So what can you do to help limit the possibility of drug-to-drug interactions?

  1. Discuss any new or planned changes to your medications, diet and health supplements with your HIV doctor and or HIV pharmacist.

They need to know everything! Some real life examples could include:

    • Has your naturopath or Chinese herbalist recommended something?
    • Did you get new medication from a different doctor’s practice because your regular doctor was unavailable?
    • Did you get over-the-counter medication from a pharmacist who is unfamiliar with your health history?
    • Did you think the vitamins/minerals on sale at the supermarket would help with your overall health?

This list is not exhaustive, but it demonstrates how easily various medication interactions can creep into your daily routine.

  1. When you start new HIV antiretroviral or other medication ensure you leave the doctor’s practice knowing the answer to this one simple question: Are there any other medications, supplements/vitamins/herbs which are contraindicated with the prescribed medication ?
  2. Try and keep your health care within one tight group of medical or allied health professionals who know your HIV status and can talk with each other. The collaboration will decrease the risk of inadvertently prescribing something which may interact with your other medications.
  3. Never accept medications from friends, family or work colleagues. What is beneficial to them may be harmful for you.
  4. Take your medications as prescribed if they are to be taken with or without food. Both are instructions which are equally important.
  5. Some medications need to be taken when there is acid in your stomach and should be taken separately to acid lowering therapies including antacids.

If you are taking antacids does your HIV prescribing doctor or pharmacist know about these? The over-the-counter immediate acid reflux relief (such as Nexium, Quick-ez and Mylanta) which are easily available on supermarket shelves, can also affect some HIV antiretroviral and other medications.

  1. If you need to take new medications from a health practitioner other than your regular doctor, always have a list of your regular medications with you and ask if they will react with your proposed new treatment. However, make sure your regular doctor also knows.
  2. Natural remedies seem harmless, but they are not always suitable when combined with some medications. So it’s wise not to start any natural remedies until you can talk to you regular HIV doctor or pharmacist.
  3. Recreational and illicit drugs can affect your prescribed medication. If you use recreational drugs either occasionally or frequently, have a conversation about any possible impacts this might have on your health with a medical professional who you trust and can talk honestly with.
  4. Be aware that as the number of different medications you take increases, so too does the chance of unwanted drug-to-drug interactions.

If you are taking more than five medications, you may be eligible for an annual review of all the medications that you take. This is a free review and called a Domiciliary Medication Management Review, or DMMR, Medicare item 900. It’s organised by and at the discretion of your regular general practitioner and conducted by an accredited community pharmacist.

No one expects you to be medication experts. That’s what your HIV health team are there for. However, if in doubt, always ask. Your health professionals want to see you get the best outcomes and are always happy to clarify things for you.

There is more information at, at or the Positive Life Factsheet pdf iconHIV & Home Medication Reviews

– Gary Keogh, RN

This article was written to offer generic health education and it should not be taken as explicit to people’s individual circumstances. Please discuss your health about medications with your regular HIV doctor and /or pharmacist.

Published in Talkabout #198 August 2021

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