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How to tell if your patients are overusing supplements


Is everybody doing it?

You’re at the pharmacy counter where you’ve just finished counselling Joan, a 65-year-old woman on her new medication for insomnia. You’ve checked all the boxes for a thorough patient encounter. You’ve updated her allergy status, checked pharmanet for her other medications, assessed drug interactions, and counselled her appropriately.

But have you asked about non-prescription medications? In particular, have you asked about supplementation?

Non-prescription supplements are on the rise

The popularity of complementary and alternative medicine has increased dramatically in recent years sending supplement sales skyrocketing worldwide. With the COVID19 pandemic this trend has only increased. People have more time than ever to research their health conditions and the supplement industry is there to offer quick solutions. Like many industries, supplement brands have pivoted during this time and are now targeting people worried about their immune health.

In my functional medicine consults I have been shocked by the number of supplements that folks are taking, with many taking upwards of 10 products a day! In recent months just about all of my new clients report a particular combination of vitamin D, C and zinc that they’ve been told will improve their immune health. Supplement companies also sell combination products for various conditions, with some sleep supplements including up to 6 ingredients!

Another disturbing trend is the lack of clinician oversight for these supplements. It once was the case that supplements beyond your classic vitamins and minerals were provided in a naturopathic physician’s office and patients could only access what had been prescribed to them. Now, high potency supplements are found in the naturals section of many pharmacies and online through retailers like amazon and When I ask my clients what prompted them to start taking these products they will often cite a YouTube video, or a blog post with no mention of a discussion with a clinician.

Joan’s Supplementation

To illustrate this point, let’s take a closer look at Joan’s supplements.

When asked what she was taking, Joan gave me the following list:

  • 1000mg wild Alaskan salmon fish oil daily for general maintenance of health
  • 1000mg flax oil daily for general maintenance of health
  • 200mg coenzyme Q10 daily for general maintenance of health
  • 1000mg vitamin C daily for immune health
  • 50mg zinc daily for immune health
  • 50 billion CFU probiotic daily for gut health
  • 100mg timed release vitamin B complex daily for general maintenance of health
  • 150mg magnesium bisglycinate nightly for sleep
  • 6000IU vitamin D daily for immune health
  • 400mg quercetin twice a day for skin health
  • 600mg resveratrol twice a day for skin health
  • 99mg potassium once a day for leg cramps
  • 500mg L-glutamine 5-6 times per day for gut health
  • 150mg milk thistle twice a day for liver health
  • 1 capsule of Ortho Sleep by AOR as needed for sleep
  • 1 capsule of Sleep Relax by Herbal Factors as needed for sleep

Of the 16 supplements listed above, none of them had been cleared by a healthcare provider prior to use.

Drug Therapy Problems


As one might expect, there were some drug therapy problems to contend with. I won’t bore you with the whole analysis, but here are the highlights:

  • Only short-term safety data for the majority of the ingredients
  • Doses above the tolerable upper limit for many ingredients including vitamin D and zinc
  • Lack of evidence supporting the use of many ingredients
  • Drug-Disease interactions present for many of the ingredients, notably:
    • Joan also suffers with uterine fibroids, a condition that could be exacerbated by hops (an ingredient in “sleep relax”), resveratrol, and milk thistle
    • Joan is post-menopausal. Vitamin C over 300mg is associated with increased risk of cardiovascular mortality in post-menopausal women.
  • Drug-Supplement interactions present
    • Additive drowsiness if the new insomnia treatment is taken with the sleep supplements

How the pharmacist helped Joan


By asking Joan one extra question at the pharmacist counter, a large list of drug therapy problems was discovered and solved. Now that she is better informed about the evidence and safety data for her supplements, Joan has opted to reduce her vitamin D dose to 1000IU per day and to stop taking 11 of the 16 supplements entirely. She has chosen to continue taking 5 supplements per day, but she knows not to expect miracles from them and recognizes that natural products are not without safety concerns. She understands that there can be serious interactions with supplements. She will avoid CNS depressants including her sleep supplement while taking the new insomnia treatment, and will check with the pharmacist before adding anything else. Her reduced supplement regimen is easier to adhere to and saves her a significant amount of money each month. Finally, Joan has been shown the value that a pharmacist can provide to her beyond just dispensing medications.

Practical Tips for Assessing Supplementation

The go-to reference for assessing supplementation is the Natural Medicines database. A monograph is available for most commonly used supplements. Here is how I use the database:

  • Ask why the patient is taking each supplement and use the database to see if there is any evidence for that indication
  • Ask how long the patient has been taking or is planning to take the supplement and ensure there is safety data for that length of time
  • Check the dosing section to ensure the dose the patient is taking is within the bounds of what has been studied and what has demonstrated safety
  • Check the condition interactions section and ensure this supplement is not exacerbating any comorbidities
  • Check the list of adverse effects and see if any of the symptoms the patient presents with could be explained by their supplements
  • Check the pregnancy and lactation section if applicable
  • Use the interaction tool to assess interactions with prescription medications
  • Check for supplement-supplement interactions (the interaction tool does not assess this) and food-supplement interactions
  • Document your process and the supplements the patient takes so you can check for changes at a later date.

Kimberley Kallio is an engineer turned community pharmacist working out of Castlegar, BC.  Since graduating from UBC in 2017, she has been drawn to preventative health, therapeutic nutrition and functional medicine.  She is passionate about educating the public about these topics, whether at the pharmacy counter or on her blog at


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