Man dies from water intoxication, and advice on how to stop this happening to you

I am a supporter of the notion that maintaining hydration in the body is important for wellbeing and health, and recommend that the prime fluid for this should be water. However, as with most things in life, drinking water is not entirely without risk. Drink too much of it and it can lower sodium levels in the body, which can lead to potentially fatal complications such as swelling of the brain (cerebral oedema). The reason I am writing about this today is because this morning I read the tragic story of a 44-year-old British man who died after drinking about 10 litres of iced water over an 8-hour period to soothe the pain of gingivitis (inflammation of the gums).

While drinking excessive quantities of water can prove fatal, the risks for most of us are very small indeed. However, the risk of this problem does escalate for individuals who participate in endurance exercise. The fundamental issue here is that many athletes can be encouraged to drink as much water (generally free of sodium) as they can to prevent dehydration (particularly in the heat). At the same time, exertion promotes sweating which speeds the loss of sodium from the body. These two factors combined leave individuals more open to low sodium levels (hyponatraemia) than they would be in normal daily life. Below, I have pasted a previous piece which focused specifically on the issue of exercise-related hyponatraemia. In this piece, I suggested limiting water consumption to 500-1000 mls per hour during endurance exercise.

In revisiting this subject for today’s blogpost, I came across a pertinent review [1]. Published in the Clinical Journal of American Society of Nephrology, this review explores the subject in depth, including the risk factors for hyponatraemia during exercise.

It lists these as:

Exercise duration >4 hours or slow running/exercise pace

Female gender (may be explained by lower body weight)

Low body weight

Excessive drinking (>1.5 litres/hour) during the event

Pre-exercise overhydration

Abundant availability of drinking fluids at the event

Nonsteroidal anti-inflammatory drugs (not all studies)

Extreme hot or cold environment

The review goes on to recommend strategies for the prevention of exercise-associated hyponatraemia (EAH). The link below goes to the full text article, and recommendations regarding this can be read in full there. Part of these recommendation regards, not surprisingly, recommended fluid intake. On this point, the advice is to: �drink only according to thirst and no more than 400 to 800 mls/hour. The higher rates of fluid intake would be recommended for runners with higher rates of exertion (e.g., heavier runners, warmer conditions, longer times of exertion). This rate of fluid intake is well below the levels of intake that are seen in athletes who develop EAH (up to 1.5 litres/hour water) but above the level that would be associated with dehydration.�


1. Rosner MH, et al. Exercise-Associated Hyponatremia. Clinical Journal of American Society of Nephrology. 2007;2:151-161

Is it possible to drink too much water during endurance exercise? ” 7th March 2004

Requests for sponsorship from individuals planning to run the London marathon have made me aware that this sporting spectacular is not too far down the road. While I am enthusiastic about the health benefits of physical exercise, endurance activities such as marathon running are, however, not without risk. For instance, while competitors in such events are generally advised to consume plenty of water, this can be overdone: in extreme circumstances, a surfeit of water may lead to lower-than-normal levels of sodium in the body that may lead to complications such as convulsions, coma and even death. The scientific literature contains more than 250 reports of this syndrome, though underreporting means that the actual numbers may well be far higher. The evidence suggests that individuals consuming an excess of water during exercise may be at risk of running to ground.

Although the replenishment of lost fluid during extended exercise is both widespread and well-accepted, this practice only came into vogue into the 1970s after being advocated as a way of staving off heat stroke. More latterly, studies have shown that dehydration can significantly impair athletic performance. Perhaps as a result of this research, drinking during exercise has filtered through to other sports too. Witness, for example, the relatively recent phenomenon of professional football and rugby players taking slurps from sports bottles during breaks in play.

While there are good reasons to keep fluid levels topped up during exercise, the potential for low sodium in the system (the medical term for which is hyponatraemia) and the complications associated with it show that it is possible to have one too many for the road. Fortunately, the risk of hyponatraemia seems to be confined to individuals engaged in sport for several hours at a time. During prolonged exercise the body may lose significant amounts of sodium via sweat. Also, extended activities such as marathon running provide sufficient time for potentially harmful quantities of water to be imbibed. The risks associated with endurance exercise seem to have been compounded by commonly-given advice that competitors should drink the maximum amount of fluid that they can tolerate. It was not until this maxim became widespread that reports of water intoxication in endurance events began flowing in.

Rather than drinking as much as can be stomached, it may be safer for individuals to consume more moderate amounts of fluid during marathons and other endurance events. This approach not only helps protect against hyponatraemia, but also reduces the risk that competitors will be slowed down by a surplus of water sloshing around the system. On the day of the event, quaffing about half a litre of water a couple of hours before hitting the road will help ensure the body is well topped-up with fluid, but also gives ample time for the body to shift any excess.

During the race itself, drinking 500 – 1000 mls (1/2 – 1 litre) of water per hour should maintain a good level of hydration with a minimum of risk. Volumes at the upper end of this range will be most appropriate for larger individuals, especially in the heat when fluid losses due to sweating are likely to be considerable. Smaller individuals, especially in more temperate climes, can generally make do with less. It seems that drinking adequate, though not excessive, quantities of water during endurance exercise is best in the long run.

6 Responses to Man dies from water intoxication, and advice on how to stop this happening to you

  1. Camel 10 July 2008 at 9:53 am #

    All the “advice” we have been given in the past to drink loads of water is just advertising propaganda by the bottled water companies. Well done for exposing Big Water and their shills.

  2. sokpuppet 10 July 2008 at 10:01 pm #

    “It seems that drinking adequate, though not excessive, quantities of water during endurance exercise is best in the long run.”

    Personally, I rate Gatorade – tasty and free from disgusting artificial sweetners and full of sodium and potassium. I’ll drink as much as I can in a race.

  3. Dr John Briffa 11 July 2008 at 6:22 pm #


    I think the role of sodium-containing drinks is discussed in the review linked to above. If my memory serves me correctly, the authors point to the fact that the sodium levels in these drinks are actually quite low. Better than nothing, though, I reckon.

  4. Lindy 11 July 2008 at 11:43 pm #

    Camel , he drunk 10 litres in 8 hours! No one advises that , they usually advise about 2 litres in 24 hours. So there is reason to still drink water. Your urine should always be pale straw coloured.

  5. Mike Abbotts 12 July 2008 at 12:26 am #

    “During the race itself, drinking 500 – 1000 mls (1/2 – 1 litre) of water per hour should maintain a good level of hydration with a minimum of risk”
    I’m an experienced marathon runner (50+ and counting), who sweats readily and weighs rather more than the average runner. I find that even on hot days, say c30 degrees c. the above recommended limited are more than adequate and actually difficult to achieve, let alone exceed. Typical water provision is a 125cc plastic cup (partly filled) every 5 miles. (Very ocasionally, 500cc bottles are on offer.)
    Perhaps, given that the problems described appear to be related to reduced sodium levels this makes case for the superiority of “sports drinks” over water – sodium being a basic ingredient in sports drinks.

  6. Rick 15 April 2009 at 3:10 am #

    I’ve developed a theory after hearing about hikers at the Grand Canyon (and other arid National Parks) suffering from water intoxication in 1999. Most of the hikers that I’ve seen at Joshua Tree National Park carry bottled water. Read the label of most bottled water and it will indicate that it has no sodium. They drink large quantities and flush the sodium from their body and aren’t replacing it with other salts (snack, sports drink or in non-processed water).

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