Kim Dong-young, a 22-year-old student, had been scratching his skin almost every day, particularly after showering.

“I can’t help but scratch my skin to death because I feel itchy and stingy all over my body at the same time,” he said. “My skin then gets blood red and swollen. It looks so ugly.” Kim applied moisturizers for the last three months, thinking that the rash may have been caused by the dry weather. However, he learned from a dermatologist last week that the rash had nothing to do with dryness, but was caused by heat.

Kim was diagnosed with cholinergic urticaria, commonly known as hives, which refers to a body condition where one is hypersensitive to heat. Cholinergic means “related to acetylcholine,” a chemical used in the parasympathic nervous system, while urticaria originates from the Latin urtica, meaning stinging nettle.

The skin reaction appears as a result of the body increasing in temperature, both passively and actively, or the precipitating release of sweat. A person with hives begins to feel an itching or stinging sensation. This may spread all over the body accompanied by red bumps.

The symptom usually appears after exercise, a hot shower, eating spicy food and sweating, but disappears within an hour.

The number of Koreans visiting clinics to treat hives has increased, particularly among teenage boys and young men in their 20s, according to the Health Insurance Review and Assessment Service.

The number of heat-induced hives patients surged nearly 25 percent from 10,000 in 2008 to 12,000 in 2012. As of last year, the percentage of male patients accounted for nearly 60 percent.

Four out of 10 hives cases appeared in male patients aged between 10 and 29, the state-run agency said. The reason why the disorder is found mostly in young males is because they are more physically active. Their chances of a higher body temperature are greater than for other age groups, HIRA explained.

In order to treat hives, it is important to keep the body temperature stable by avoiding hot showers, hot baths and prolonged exercise. It is also important to give some time for the body to adjust slowly to higher temperatures when entering indoors during winter. Lowering stress is also important because it could also increase the core body temperature, doctors say. The treatment can take months and the symptoms can reappear because it is a chronic disease. Medications such as antihistamine would help to ease symptoms, but it is more important to avoid situations that increase the body temperature, they added.

By Cho Chung-un (christory@heraldcorp.com)