[Sportschosun Reporter Jang Jong-ho] On June 17, the Korea Disease Control and Prevention Agency (KDCA) issued a nationwide Japanese encephalitis alert and advised people to wear long clothing and use mosquito repellent on exposed skin, clothing, shoes and socks when going outdoors. The measure came after Japanese encephalitis virus genes were detected in captured mosquitoes.
The problem is that the standards for choosing and applying repellents differ for children and adults.
The Korea Children's Hospital Association, chaired by Choi Yong-jae, director of Uijeongbu Ttunttun Children's Hospital, said, "Much of the parenting information on the internet is copied from U.S. or Canadian guidelines,
so there are many cases that do not match domestic approval standards," adding, "Most problems can be avoided by checking just two things: the ingredients and the age at which the product can be used."
The association, together with Choi, compiled the mosquito repellent questions parents ask most often in clinics into a Q&A.
◇When choosing
-How can you tell whether it is really a mosquito repellent?
▶The container or package must be labeled as a "quasi-drug." If that label is missing, the product has not been confirmed by the Ministry of Food and Drug Safety to have mosquito-repelling effects.
According to a survey released in August 2025 by the Seoul Institute of Health and Environment, only 28 of 52 mosquito repellents collected from the market, or 54%, were quasi-drugs. The rest were air fresheners, household chemical products or cosmetics. In particular, bracelet, sticker and patch types are not approved mosquito repellents.
The Ministry of Food and Drug Safety says there are no bracelet- or sticker-type repellents approved as quasi-drugs, and the survey also found that all patch and band types were not quasi-drugs. In an experiment conducted in the United States and published in The New England Journal of Medicine in 2002, mosquitoes bit through a repellent wristband after an average of 12 to 18 seconds. Parents should not assume that sticking one on a child's clothes or stroller is enough.
-What should you look for in the ingredients?
▶Only four active ingredients are approved in Korea for mosquito repellents. You can check the ingredient list on the back of the product.
DEET is the longest-used ingredient. It works by preventing mosquitoes from detecting human body odor and carbon dioxide. Icaridin has less odor and stickiness and is less likely to damage plastic, so it is often chosen for children. IR3535 is less irritating, but its effect does not last as long, so it must be reapplied more often.
Among them, IR3535 is listed domestically as "ethyl butylacetylaminopropionate," which is hard to recognize.
There is a trick. For repellents approved in Korea, the active ingredient is written in parentheses after the product name. For example, it may be labeled "○○○ Gel (icaridin)," so just check the parentheses.
In the end, you should check the parentheses, not the brand name.
-Does a higher concentration provide stronger protection?
▶No. Concentration determines duration, not strength.
A concentration that is twice as high does not block twice as many mosquitoes. It only means the effect lasts longer. There is no reason to use a high concentration for children.
Under domestic guidelines, the Ministry of Food and Drug Safety says mosquito repellent generally lasts four to five hours.
So it is better not to reapply it before four hours have passed. Using too much, or using it for too long, can cause allergic or hypersensitivity reactions such as redness of the skin.
In the U.S. experiment cited above from 2002, 4.75% DEET lasted about 1 hour and 30 minutes, while 23.8% lasted about 5 hours. However, those were laboratory conditions, and the duration became much shorter when people sweated or went swimming. For DEET, the duration no longer increased beyond around 50% concentration. Icaridin showed wide variation across studies, with both 5-hour and 10-hour results reported at the same 20% concentration, so the association does not specify a particular figure.
-The internet says "once a day" or "up to three times a day."
▶That is the standard of Canada Health, not Korea's.
Instead of setting a fixed number of applications per day, the Ministry of Food and Drug Safety advises people to follow the directions and dosage on the product and not to apply it again within four hours. For products purchased in Korea, it is best to follow the instructions on the package.
◇When applying
-How should it be used for a baby who is not yet one year old?
▶For infants under 6 months old, physical protection should be used instead of repellent.
It is best to cover strollers and cribs with mosquito nets and dress the baby in thin, long-sleeved clothing and long pants. Avoiding outdoor activity around dusk and dawn, when mosquitoes are most active, can also greatly reduce the risk. Strongly scented lotions and perfumes should also be avoided.
-How should it be applied to children?
▶Do not let the child hold the container. An adult should dispense it into their own hand first and apply it for the child.
According to the Ministry of Food and Drug Safety's instructions, it should be applied to exposed skin such as the arms, legs and neck, as well as the top of clothing, socks and shoes. On the other hand, it should not be sprayed directly on the face. Instead, put it on your hand first and apply a thin layer around the eyes and mouth, avoiding those areas. Children's hands and fingers often go into their eyes or mouths, so it should not be applied to cuts, eczema or sunburned skin either.
-Can it be used together with sunscreen?
▶There is an order. Apply sunscreen first, then apply the repellent after it has been absorbed. Doing it the other way around means you will end up applying the repellent over the sunscreen and rubbing more than necessary. Combination products that claim to do both are not recommended. Sunscreen needs to be reapplied often, but repellent should not be.
Another thing to note is that DEET can damage plastic and synthetic fibers. It is recommended to keep it away from eyeglass frames, watches, smartphone screens and clothing made of performance fabrics.
-What should you do after coming home from outside?
▶Once you get home, wash the applied areas with soap and water.
Do not let the child sleep with it still on, and it is also best to wash any clothing that was exposed to it. If the applied area turns red or a rash or itching develops, wash it off immediately and stop using it. If symptoms continue, it is best to visit a pediatrics clinic with the product you used. That is because identifying the ingredient makes diagnosis much more accurate.
◇Common misconceptions
-If it says "natural ingredients," is it safer for children?
▶The word "natural" does not mean safe. In fact, allergies are more often triggered by fragrance ingredients.
A representative example is citronella oil. Because there was not enough evidence for safety or repellent effectiveness, it was excluded from quasi-drug approval after 2017. In the U.S. experiment cited earlier, a 10% product was bitten through in about 20 minutes, and a 5% product in about 14 minutes. In the survey by the Seoul Institute of Health and Environment, about 75% of the products examined, or 39 of 52, contained at least 0.01% of allergenic ingredients such as geraniol, citronellol and linalool.
Lemon eucalyptus oil (para-menthane-3,8-diol, PMD) is different.
It is also an approved active ingredient in Korea and showed about two hours of protection in the experiment above. However, in Korea it can only be used for children aged 4 and older. The U.S. Centers for Disease Control and Prevention (CDC) does not recommend it for children under 3, so Korea's standard is one year stricter. Parents should not use it on young children just because it is described as a "natural ingredient recognized in the United States."
-If you apply repellent properly, do you no longer need to worry about Japanese encephalitis?
▶Repellent is a way to reduce mosquito bites, while Japanese encephalitis is prevented through vaccination. In other words, the two are not substitutes for each other.
Anyone born in 2013 or later is eligible for the national routine immunization program for Japanese encephalitis. Vaccinations should be completed according to the standard schedule. According to KDCA data, 65.9% of the 79 Japanese encephalitis patients reported over the past five years, from 2021 to 2025, were in their 50s or older. The reason there are fewer cases among children is not because there is no risk, but because they are being vaccinated.
Choi Yong-jae, head of the Korea Children's Hospital Association, said, "Mosquito repellent is one of those items that almost never gets left out of a child's summer bag, but not many parents actually know which ingredient can be used from what age before buying it." He added, "It only takes a moment to check the one line listing the ingredients on the back of the product."
He continued, "Sometimes a choice made with good intentions does not help the child. That is the case when parents buy sticker or bracelet products to attach to a child's clothes and feel reassured, or when they see the word 'natural' and assume it is safer. Natural is not another word for safe."
He also said, "Repellent is only a tool to reduce mosquito bites; it cannot replace vaccination. Since a nationwide Japanese encephalitis alert has been issued, please check your child's vaccination schedule as well." He added, "If the applied area turns red or a rash appears, you should visit a pediatrics clinic with the product you used."
Jang Jong-ho, bellho@sportschosun.com
This article has been translated by GripLabs Mingo AI.
