Doctors Say Drinking Too Much Water Can Be Dangerous

Advising patients to "stay hydrated" when ill could actually make things worse, according to King’s College Hospital doctors.
Phoebe Hurst
London, GB
December 2, 2016, 12:33pm

When lying in bed with the flu, suffering from food poisoning, or just hungover AF, there's not much you can do aside from stay cocooned in your bed, ideally in front of a new episode of Planet Earth. Oh, and take in lots of fluids. Yeah, we know, mum.

But the age-old advice to sip water, chicken soup, or Lucozade when ill could actually be harmful. In a recent report in the BMJ Case Reports journal, doctors at King's College Hospital wrote that the instruction to drink water when unwell lacked evidence.

READ MORE: You Might Actually Be Drinking Too Much Water

Writing in the journal, they said: "We frequently advise our patients to 'drink plenty of fluids' and 'keep well-hydrated' when they are unwell. But, what do we mean by that? Are there potential risks of this apparently harmless advice?"

The doctors asked this question when treating a woman who had drunk too much water after she developed the symptoms of a urinary tract infection. On the advice of a doctor, she had drunk half a pint of water every 30 minutes in an attempt to "flush out her system."


This landed the woman in A&E, where she was found to be suffering from acute hyponatraemia, a condition caused by low salt levels in the blood which can occur when someone drinks too much water in a short period of time. It can cause vomiting and headaches and in extreme cases, seizures, comas, and even death.

Doctors were eventually able to save the woman's life by restricting her fluid intake to a litre over the next 24 hours.

The journal report concluded: "As demonstrated here, the harmful effects of increased fluid intake include confusion, vomiting and speech disturbance, and potential for catastrophic outcomes due to low blood sodium concentrations."

READ MORE: This Man Survives on Exactly Zero Glasses of Water a Day

The King's College doctors aren't the first to question the water-glugging advice doled out by medical professionals. Earlier this year, a study from Monash University in Australia advised people to "just drink according to thirst rather than an elaborate schedule" and recent recommendations from the Harvard Health Letter stated that we really only need around four to six glasses of water a day—not the hallowed eight.

So, how much H2O should be be chugging back? Commenting on the King's College Hospital study, Dr. Imran Rafi of the Royal College of GPs said: "We would encourage patients to drink more if they have symptoms of dehydration, such as feeling thirsty—including in hot weather or when exercising—or passing dark-coloured urine. There is no steadfast recommendation as to how much water people should drink in order to stay healthy, but the key thing is to keep hydrated—and passing clear urine is a good indication of this."

You heard the doc.