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A Modern Pharmacist · August 2 · 24 min

Your Electrolyte Drink Doesn't Work

Electrolytes are now a $40 billion industry, expected to double within five years — and the marketing is good enough that it made me question basic physiology I've known for years. So I went and looked properly. I'll tell you upfront: I don't use electrolytes regularly myself, though I have in the past year or so on a few occasions — and this episode is me working through whether the evidence actually supports their use for the average person, with full study citations so you can check it yourself. I start with the physiology: how sodium, potassium, calcium and magnesium are kept within tight ranges in the blood, and why sodium behaves completely differently to the others. I bust the biggest myth in this space — sweat is hypotonic, meaning when you sweat, your blood doesn't get diluted, it actually becomes more concentrated. From there: a practical rule for under an hour of exercise on a normal diet (you likely don't need anything but water), where the evidence does support electrolyte drinks (prolonged exercise, heat, endurance events), how to actually read a sodium label and compare real products, and why morning salt water doesn't hold up. Then the context where electrolytes are genuinely life-saving: acute illness. I cover the research behind a 69% reduction in diarrhoea mortality with oral rehydration therapy, and why this is completely different physiology to a normal workout. I close with a quick tour of potassium, calcium and magnesium, and a clinical example from my own practice — patients on diuretic medications that directly block electrolyte reabsorption in the kidney, who very often still have completely normal blood results, which tells you a lot about how robust this system actually is. Physiology foundation: Hall JE & Hall ME (2020). Guyton and Hall Textbook of Medical Physiology, 14th edition. Key studies: McCubbin & Costa (2018, Int J Sports Sci) · Del Coso et al. (2016, Scand J Med Sci Sports) · Hew-Butler et al. (2006, Br J Sports Med) · Munos, Fischer Walker & Black (2010, Int J Epidemiol) · ACSM Position Stand on Exercise and Fluid Replacement · NDNS 2018/19 · CDC/NHANES 2021–2023 This is informational purposes only, not medical advice. If you can't get seen by your own physician, by all means do so, but always speak to your own healthcare provider. New episodes every week — subscribe so you don't miss the next one.

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Electrolytes are now a $40 billion industry, expected to double within five years — and the marketing is good enough that it made me question basic physiology I've known for years. So I went and looked properly. I'll tell you upfront: I don't use electrolytes regularly myself, though I have in the past year or so on a few occasions — and this episode is me working through whether the evidence actually supports their use for the average person, with full study citations so you can check it yourself.

I start with the physiology: how sodium, potassium, calcium and magnesium are kept within tight ranges in the blood, and why sodium behaves completely differently to the others. I bust the biggest myth in this space — sweat is hypotonic, meaning when you sweat, your blood doesn't get diluted, it actually becomes more concentrated. From there: a practical rule for under an hour of exercise on a normal diet (you likely don't need anything but water), where the evidence does support electrolyte drinks (prolonged exercise, heat, endurance events), how to actually read a sodium label and compare real products, and why morning salt water doesn't hold up.

Then the context where electrolytes are genuinely life-saving: acute illness. I cover the research behind a 69% reduction in diarrhoea mortality with oral rehydration therapy, and why this is completely different physiology to a normal workout. I close with a quick tour of potassium, calcium and magnesium, and a clinical example from my own practice — patients on diuretic medications that directly block electrolyte reabsorption in the kidney, who very often still have completely normal blood results, which tells you a lot about how robust this system actually is.

Physiology foundation: Hall JE & Hall ME (2020). Guyton and Hall Textbook of Medical Physiology, 14th edition.

Key studies: McCubbin & Costa (2018, Int J Sports Sci) · Del Coso et al. (2016, Scand J Med Sci Sports) · Hew-Butler et al. (2006, Br J Sports Med) · Munos, Fischer Walker & Black (2010, Int J Epidemiol) · ACSM Position Stand on Exercise and Fluid Replacement · NDNS 2018/19 · CDC/NHANES 2021–2023

This is informational purposes only, not medical advice. If you can't get seen by your own physician, by all means do so, but always speak to your own healthcare provider.

New episodes every week — subscribe so you don't miss the next one.

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