The National Health Insurance Assessment and Service (HIRA) urged citizens to take caution as sunburn patients are increasing in number annually with a majority of the cases happening in August.

According to medical big data of the HIRA, the number of patients suffering from sunburn increased from 8,868 in 2014 to 10,991 in 2015, 11,743 in 2016, and 11,106 in 2017.

Because many people self-medicate themselves at home without going to the hospital, the actual number of patients is estimated to be higher, the government agency said.

The patients in August accounted for 31.4 percent of the total sunburn cases, and the patients in August and July accounted for half of the total patients.

By age group, those in their 20s, who enjoyed active outdoor lives, had the most cases of sunburns with 29.6 percent, followed by 30s with 28.9 percent and 40s with 17.2 percent.

Sunburns are inflammatory reactions on a person’s skin caused by ultraviolet B (UVB), a leading cause of sunburn, skin cancer, photo-aging, and pigmentation. Symptoms include red spots and a prickling sensation and usually occur to people who stay out in the sun for an extended period.

Daylight sunburns appear four to six hours later after exposure to ultraviolet light. As the skin becomes red, the skin becomes hot, swollen and itchy. It can also create blisters and cause the skin to peel off. Symptoms often last more than a week, while the higher the exposure to ultraviolet light can make symptoms worse.

Those exposed to sunburn should cool the area and lower the skin temperature around the burn and visit hospitals to treat blisters.

"To prevent sunburn, it is best to avoid outdoor activities from 11 a.m. to 100 p.m., and apply sunscreen with a high sun protection factor (SFP) outdoors," a HIRA official said.