Drinking too much water when ill may do more harm than good

Doctors have always advised patients to drink plenty of water if unwell. A new case study reports the risks of drinking too much water and highlights the need for more research to support this traditional advice. For generations, the predominant medical advice in case of flu or respiratory infections has been to drink plenty of fluids. Theoretically, this is considered good advice; during a cold, the body secretes more liquids through the nose or may be running a fever, which could lead to more fluid loss. In the case of infections in general, drinking more water is thought to help with intravascular volume loss, increased vascular permeability, as well as replace the fluids lost in fever and vomiting. The medical advice to drink plenty of water also rests on the assumption that water consumption is harmless. A new case report reminds doctors and patients that evidence for the benefits of drinking plenty of water is scarce, and, in fact, drinking too much water can be dangerous.

Water intoxication in a woman with a simple UTI

A new paper, published in BMJ Case Reports, details the case of a 59-year-old woman who drank too much water as a result of her urinary tract infection (UTI). The woman started to feel the symptoms of a recurring UTI, which had flared up several times in her life previously. In the case of UTIs, drinking more water than usual has been shown to temporarily reduce the number of bacteria in urine, but the reasons for this remain unclear. Remembering the doctor’s advice of drinking half a pint of water every half hour, the woman drank several liters of water that day, but her UTI symptoms worsened. As a result, she presented herself to the emergency department at King’s College Hospital in the United Kingdom with symptoms of lower abdominal pain and dysuria. Urine tests confirmed a UTI, but the patient was otherwise healthy. She had no medical history apart from a recurring UTI, did not smoke or take any medicine or recreational drugs, had no allergies, and was a moderate alcohol drinker. In the emergency department, the woman was prescribed antibiotics and analgesics for her UTI. However, she soon started displaying new symptoms, such as shakiness and tremor, vomiting, and speech difficulties. The patient’s Glasgow Coma Scale was 15 – she had an attention deficit, was hesitant in speech, and had difficulty finding her words. Otherwise, the patient was healthy. Because of her speech impairment, doctors considered the possibility of a stroke. Blood tests and a computed tomography (CT) scan quickly revealed this was not the case. However, blood tests showed signs of hyponatremia.

Excessive water consumption may lead to acute hyponatremia

Hyponatremia is a medical condition caused by abnormally low levels of sodium – lower than 134 millimoles per liter. Acute hyponatremia, which develops in less than 48 hours, is considered an emergency, as it can have fatal neurological consequences. Critically low levels of sodium can lead to cerebral edema with increased levels of intracranial pressure and brain herniation. This leads to seizures, coma, and death. The mortality rate for hyponatremia cases is 17.9 percent. In the case report, the patient’s sodium level was 123 millimoles per liter. The fatality rate for patients with sodium levels lower than 125 millimoles per liter is almost 30 percent. Water intoxication, which can lead to fatal hyponatremia, has been reported in endurance exercise, in the use of the drug MDMA, and in psychogenic polydipsia – a disorder where the patient drinks large quantities of water compulsively, usually as a result of a psychiatric condition. After having her water intake restricted to 1 liter per day, the patient’s condition improved significantly in the following 24 hours. Sodium levels were back to normal, and the patient was discharged.