If Heat Makes You Sick During Your Japan Trip

Heat illness covers the various symptoms that arise when heat keeps the body's temperature control from working well — the condition called 「熱中症」 (heat illness) in Japan. It can strike not only in the sun but also while resting in a hot, humid indoor space.

Watch out too for heavy sweating or weakness in the hands and feet. Don't diagnose yourself or assume you're fine based on body temperature or sweating alone. Check together whether they're alert, whether speech and walking look normal, and whether they can drink water on their own. If anything is off, cool the body right away and ask for help.

Before leaving and before going out at your destination, check the issued time, target dates, and areas. The heat index isn't the same number as the temperature in a weather app or a body temperature. Use the nearest observation point's value, but remember the sun and wind where you actually are may differ — watch your surroundings and your body too.

The regular heat illness alert, 「熱中症警戒アラート」 (heat illness alert), is issued when the day's highest WBGT is forecast at 33 or above at any point in the target area. That 33 doesn't mean an air temperature of 33°C. Heat illness can strike without an alert, depending on your condition, activity, and surroundings.

「熱中症特別警戒アラート」 (heat illness special alert) is a special notice that dangerous heat is expected across multiple areas with a risk of serious health harm. Stay in a cool place and watch your companions too. If you're heading to an event, first check whether the organizer canceled it or changed the date or venue, then set out.

On hot days, cut back on going out around midday as much as possible. The Ministry of Health, Labour and Welfare also recommends resting in shade often and avoiding the heat. Indoors, control the temperature with air conditioning and drink fluids often.

It's good to cut plans with long walks or outdoor lines first. After seeing one place, build in rest time at your lodging or in air-conditioned spaces. Even if you shift plans to morning or evening, check the heat index and your condition for those hours before moving.

Children and older adults regulate body heat differently, so they need extra care. Ask your companions whether they're too hot or struggling. If they seem less energetic than usual or respond differently, stop the activity. If it's a long walk to a rest spot, it's better to shorten the plan.

A cooling shelter is an air-conditioned facility a municipality designates as a place to escape the heat; in Japanese it's called 「クーリングシェルター」. When a heat illness special alert is issued, it opens at set hours. The city or ward office provides details like available dates and hours.

Being on a list doesn't mean you can enter now — check separately. Look at the facility notice's open dates and hours, and ask staff where you can rest when you arrive. If you can already stay in an air-conditioned place, you don't have to move to a cooling shelter.

Rather than walking far in the heat to find a specific facility, ask for help nearby first. If consciousness or walking looks abnormal, or the person can't drink water on their own, don't spend time searching for a facility — call 119 and cool the body.

Going inside doesn't remove the heat risk. Heat illness can happen indoors too, so control the temperature with air conditioning. If dizziness or headache continues, get medical care. Call 119 if someone is unconscious or can't drink water on their own.

If the air conditioning is broken or there's a power outage, ask staff whether there's a cool place to rest, whether you can move to another room, and when the cooling will be back. If you need to move to another lodging, ask the lodging and your booking operator separately about change fees and conditions. Don't assume in advance that you can switch rooms or cancel for free.

Even after evacuating for an earthquake or the like, a shelter may have no air conditioning, or its air conditioning may not work during a power outage. If the heat makes you sick, tell staff right away and ask for help resting somewhere cool.

The Ministry of the Environment's first aid materials also recommend staying calm and resting enough after you improve. If nausea or vomiting keeps you from drinking water, or your condition worsens, call 119.

While recovering, drop plans with long walks or outdoor waits, and first pick rest spots with your companions. Don't force yourself to travel while sick just to catch a booked train or flight.

Once you can move, check separately whether trains and buses from your lodging to the station or airport are running and whether your booked flight is operating. Transport may still be stopped even if you feel better. If you need to change bookings, ask the operator, airline, or booking company about how to change and what it costs. A heat alert doesn't mean every booking is changed or canceled for free.

Show people around you: 「救急車を呼んでください。」 — it means "Please call an ambulance." Also tell them the facility's name and location. In an emergency, call 119 first instead of waiting for a Korean-language counselor to connect.

JNTO's Japan Visitor Hotline is a phone line that guides foreign travelers in Japan when they're in trouble from illness or disaster. It's available 24 hours a day in Korean, English, and Chinese. In Japan call 050-3816-2787; from abroad call +81-50-3816-2787. If you need an ambulance, call 119 first, before this line.

If it's not an emergency and you need a hospital, use JNTO's Korean medical institution search to pick a region and language. Contact the hospital to ask about available hours, whether they can explain in the language you want, and whether you can be seen now. JNTO generally doesn't interpret between patients and hospitals or book on your behalf. Korean guidance doesn't guarantee interpretation, treatment, or booking.