In a rare medical case, a woman in her 70s was hospitalized with heat stroke after stretching in a sauna for 45 minutes.

A woman in her 70s experienced severe heat stroke after a 45-minute sauna session, causing her body temperature to dangerously rise to 107.6°F. She was hospitalized with multiple complications including seizures and kidney injury but eventually made a full recovery.

Most cases of heat stroke occur on hot days, due to overexertion, researchers say. However, “sauna use is a rare but potentially important cause of classical heat stroke,” Dr. William Jack McIver with Birmingham Heartlands Hospital in the UK wrote in a study published Jan. 7 in the journal BMJ Case Reports.

"Sauna use is a rare but potentially important cause of classical heat stroke," the doctors of a new case report warn.

Prolonged sauna sessions may put bathers at risk of heat stroke, especially if they haven't consumed enough water beforehand, doctors have warned in the journal BMJ Case Reports. The warning comes after medical professionals treated a woman in her early 70s who required hospital admission following an extended sauna session at her local gym.