Should you ‘drink lots of fluids’ when sick? More evidence needed, doctors say

The first thing we hear when someone catches a cold or another common illness is “drink lots of fluids.”

Health Canada lists “fluids” as a treatment for mild flu symptoms, and while the Kidney Foundation of Canada recommends going to the doctor if you have a Urinary Tract Infection (UTI), it also recommends to “drink plenty of water (about six glasses a day).”

But a new case study published in the BMJ Case Reports journal is calling for more research into this recommendation.

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Report co-author Dr. Laura Lee says there are theoretical benefits to drinking more fluids, but there’s been very little proof to support this claim.

Doctors recommend drinking fluids because when you have an infection, “you can sweat more, breath faster and have episodes of vomiting,” Lee said in an email to Global News.

“However, there is not much hard evidence behind this advice and there is very little evidence as to what type of fluid to drink.”

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The study, by two U.K.-based doctors, looked at a case where one woman with a UTI developed hyponatraemia (or water intoxication) after drinking too much water in an attempt to “flush out her system.”

The 59-year-old woman drank several litres of water in a day, resulting in the condition, which occurs when the level of sodium in the body is abnormally low.

Her symptoms subsided when doctors restricted her water intake to one litre per day.

But this is only one case; Lee suggested that “more research is needed into how much fluid to drink and what type of fluid to drink during illness.”

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It’s a call for doctors to “qualify our advice to drink more fluids with more research,” she said.

But exactly how much are you supposed to drink a day? That’s a difficult question to answer, Lee said.

While the Dietitians of Canada guidelines include drinking 3 litres of fluid for men and 2.2 litres for women, Health Canada doesn’t list recommendations because “a wide range of intakes are compatible with normal hydration, and thus a specific requirement could not be set.”

Lee also said there is currently no agreed recommended daily intake of water in the UK.

She said it depends on “how much activity you engage in, the climate, your metabolism etc.”