Getting Caught in the Rain Does Not Cause Flu, IPB Expert Says

The belief that soaking-wet hair from rain, or washing one’s hair in rainwater, triggers flu and headaches is a myth. Medically, rain and wet hair are not direct causes of illness.

Citing a statement from Bogor Agricultural University (IPB), dr Widya Khairunnisa, a lecturer at IPB University’s Faculty of Medicine and Nutrition, said healthy people generally need not worry about getting wet in the rain.

“Medically, washing your hair in heavy rain is not dangerous for a healthy person, provided you rinse afterwards with clean water and dry your hair promptly,” she explained.

Widya said flu, or the common cold, is a respiratory infection caused exclusively by viruses, not rainwater or wet hair. Simply getting caught in the rain will therefore not automatically make someone ill.

Nevertheless, exposure to cold rainwater can trigger certain physiological responses in the body.

“In cold conditions, blood vessels in the skin constrict to preserve body heat. This can make someone shiver and feel uncomfortable,” she said.

Cold air accompanying rain can also affect the mucous membranes in the nose and respiratory tract. Such weather can disrupt mucociliary clearance—the body’s natural system for removing mucus and germs—and weaken local immune defences in the nose.

Another important factor to consider is the quality of the rainwater itself. As raindrops pass through the atmosphere, they can collect dust, air pollutants, microorganisms and other harmful substances, which may then settle on the hair and scalp.

“Under certain conditions, exposure to pollutants may trigger oxidative stress and inflammation, although research directly linking rainwater to hair and scalp disorders remains limited,” Widya said.

People are therefore advised to rinse their hair with clean water and dry it promptly after getting caught in the rain. If they have been exposed to rain for a long time, particularly in a highly polluted area, washing their hair with a mild shampoo is strongly recommended to remove any particles that have settled on it.

Extra caution is still warranted among vulnerable groups. Although cold exposure does not directly cause infection, it can trigger or worsen symptoms in people who have a fever, are extremely fatigued, have a respiratory infection, or have a history of asthma or rhinitis.

“The issue is not washing your hair in the rain, but prolonged exposure to cold, water quality and a person’s state of health,” she concluded.