Oil pulling, the practice of taking an oil like sesame or coconut oil and swishing it in your mouth for 10-20 minutes, is a traditional remedy that has been used in India for hundreds of years. The reported benefits of this toxin-removing practice range anywhere from increased oral health to healing immune disease. But there is a hidden danger to oil pulling.

A recent case study published in the International Journal of Tuberculosis and Lung Disease detailed the story of a patient who came in for treatment for pneumonia four times over the course of six months. Doctors tried to figure out why she kept coming down with a very specific type of pneumonia called lipid pneumonia that’s caused by oil in the lungs. After asking about her diet in much detail, they finally found out that the patient had started oil pulling two weeks prior to her first hospitalization. The oil, full of bacteria from her mouth, had been inhaled in small amounts during her oil pulling and accumulated in her lungs, causing the pneumonia infection.

It seems the risk of lipid pneumonia is low for most people, as this is not a problem that’s widely known about or published, however it may be advised for populations such as children or the elderly who could have problems with controlling a swallowing reflex, or those with impaired sinuses who may have problems breathing easily through their nose, to avoid oil pulling.