By Nina Hermansen, AAU Communication and Public Affairs
Photo: Colourbox

Europe has been hit by a heat wave, and in several places the authorities are reacting with bans on alcohol in public places. Denmark faces a weekend with temperatures above 30 degrees at the same time as the opening of Roskilde Festival, among others.

But is it dangerous to drink alcohol in the heat, and are you at greater risk of dehydration?

Not necessarily, states Peter Holland-Fischer, Clinical Associate Professor, Aalborg University and Senior Physician, Aalborg University Hospital:

"It is a myth that alcohol causes you to lose fluid to a degree that is problematic. Alcohol is not a diuretic to a degree that has any practical significance. You do urinate more, but that's not surprising if you've consumed three large draught beers at once."

Alcohol makes you less able to react in the heat

According to the senior physician, the best studies show that alcohol only has a limited effect on the body's fluid balance. Alcohol affects the hormone ADH (antidiuretic hormone) that regulates urine production, and this can theoretically lead to increased urination. But in practice, research shows that the effect is very modest, and studies have shown only a temporary increase in urine volume of 0.5–1.5 percent.

And, analyses of the composition of the urine do not indicate a significant effect on dehydration.

However, with the caveat that the studies are primarily based on moderate intake and that there is a lack of data on women.

According to Peter Holland-Fischer, the greatest risk of consuming alcohol in the heat lies somewhere other than fluid balance.

"Alcohol weakens the systems in the brain that enable us to think clearly, and this can mean that you overlook the body's warning signals or take greater risks. So, if you are heading towards

dehydration or overheating, there is a real risk that you and those around you will not act quickly enough," he says.

He therefore also recommends great caution. The classic advice of one glass of water per standard alcoholic drink can be increased to two, and Peter Holland-Fischer hopes that more people will become aware that they should not swim if they have consumed alcohol, as the risk of drowning accidents increases.

"So, it's not about alcohol's effect on your fluid balance in itself. It's about judgment. You need it when your surroundings are hazardous, and at high temperatures they are.

Translated by LeeAnn Iovanni, AAU Communication and Public Affairs