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5 Types of Heat Packs: How to Stay Warm on Cold Winter Days in Japan

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Heat packs or pocket warmers (also called "kairo" in Japanese) are very popular items in Japan during the colder months. This article introduces five different types of pocket warmers, their use, and where to buy them.

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Using Heat Packs in Japan

Winter in Japan is a season with so many great attractions such as snow onsen, skiing, illuminations or winter festivals such as the Sapporo Snow Festival.

In spite of what you might imagine, the Japanese winter can be very harsh and cold. You might be wondering how to stay warm when you are out and about.

Japan has a very nifty solution for this problem: heat packs! Read to learn what they are, where you can buy them, and recommended items to keep you feeling comfortable even on cold days.

What are Japanese Heat Packs?

5 Types Of Heat Packs - How To Stay Warm In The Japanese Winter

You might know the pocket warmer you can stick in your pockets to keep your hands warm. Most of them are microwavable.

Japanese heat packs, also known as kairo in Japanese, are very similar to that. The only difference is that they are self-heating and one-time use only.

Another difference is that there are many different types of heat packs, not only the one that warms up your hands.

One very important word to look out for when you choose your heat pack is the word "haru" (written 貼る or はる), which means "to stick to" in English.

5 Types Of Heat Packs - How To Stay Warm In The Japanese Winter

If you want the sticky type of heat pack which you can stick to your clothes, you need to search for the "haru" type. Some of the sticky heat packs also feature an image that resembles peeling off a sticker.

5 Types Of Heat Packs - How To Stay Warm In The Japanese Winter

If you want the normal pocket warmer you need to look for not sticky, "haranai" in Japanese (written 貼らない or はらない).

How to Use Japanese Heat Packs

Even though the styles differ, most heat packs work the same way. Pressure and air trigger a chemical reaction with the iron sand that they contain making them heat up.

Once you take the heat pack out of the package, you should play with it for a little bit. Rub it together or squeeze it. You should feel it heating up after a short time. Now it's ready to use.

No need to worry, though, heat packs never become burning hot. Most of them heat up to a comfortable temperature of about 40 degrees Celsius.

Where to Buy Heat Packs in Japan

Heat packs are sold throughout Japan at large retailers like Don Quijote and drugstores like Matsumoto Kiyoshi. Convenience stores also sell heat packs. If you plan on using them frequently in winter, be sure to purchase a box of 15 or 20, which will generally cost less than 1,000 yen.

Starting from fall, these warmers will be placed close to cash registers and at the front of store entrances at most shops, so you can easily pick them up when in need. Hundred yen stores also carry heat packs.

Introduced below are five types of Japanese heat packs you might want to try for yourself.

1. The Original - The Pocket Heater

5 Types Of Heat Packs - How To Stay Warm In The Japanese Winter

The non-sticky pocket heater is the traditional type. It's like a little pillow which is meant to keep your hands warm.

You activate it and stick it into your pockets or hold it in your hands. It is especially useful if you don't have gloves.

The pocket heater is also available in a mini version (written ミニ). The mini pocket heater is about half the size of the original. Some people like to use the stick type minis into their gloves or socks to keep their hands and feet warm.

The normal size pack stays warm for up to 20 hours, while the minis only up to 10 hours.

2. The Attachable Type - Sticky Heat Packs

5 Types Of Heat Packs - How To Stay Warm In The Japanese Winter

As mentioned before, there is a sticky version of the common heat pack as well. Search for the "haru" on the package.

You can peel off the seal on the back and stick them anywhere on your clothes. They are great for keeping warm as well as treating any kind of minor aches.

Please refrain from applying them directly to your skin! They are not made for direct skin contact. The sticky side gets very hot. The glue can cause allergic reactions when applied directly to the skin.

However, if you use them as intended they are extremely useful. Some people like to cover themselves with them if they are out and about in winter.

The sticky type of heat packs stays heated for up to 12 hours.

3. Toasty Shoes - Heat Packs for Your Feet

5 Types Of Heat Packs - How To Stay Warm In The Japanese Winter

The heat pack for your shoes is a new variation. For people whose toes tend to get extremely cold and painful if you are walking in the cold,
Japan has a couple of variations available to solve this problem. 

The first variation is a sticky heat pack meant for your socks. Some people like to stick them on the top of their sock instead of the bottom because they can feel hot when you step on them. As with the other sticky heat packs, please don't apply them directly on your skin.

The other type is a heat pack you stick into your shoes. These are available as half insoles and full insoles. The bottom of them is covered with a non-slip material like foam or rubber and the top is the heat pack. The half insoles just keep your toes warm, while the full insoles heat up over the whole length.

The sock and the shoe heat packs are easy to tell apart. One has socks on the package, the other showcases shoes.

Most of these heat packs stay hot for up to 5 hours.

4. Easing Pain - Medical Heat Packs

5 Types Of Heat Packs - How To Stay Warm In The Japanese Winter

Medical heat packs are made to be directly applied to the skin. They are perfect to ease backaches or muscle aches with heat. They don't contain medicine, so they can also be used to stay warm.
Even though they also supposedly heat up to 40 degrees Celsius, they don't get as hot as the other heat packs.

They stay warm for 5 to 8 hours.

5. For Tired Eyes - The Heated Eye Mask

5 Types Of Heat Packs - How To Stay Warm In The Japanese Winter

The heated eye mask is made for tired eyes. You can use it anywhere you want to relax. Of course, using it at night is one option. However, it's also perfect for when you travel. You can use it on the train, on a highway bus or on the airplane. You will wake up refreshed and your eyes will feel relaxed.

The mask heats up for 10 minutes but will keep its heat for quite a while.

Stay Warm This Winter with Heat Packs

There are so many types of hot packs to choose from. They all serve a different purpose and it's hard to pick a favorite. We're pretty sure you'll find them useful.

How about trying some this winter and decide for yourself which one will become your go-to heat pack?

FAQ

How do you use a Japanese heat pack?

Using a Japanese heat pack, or kairo, is a simple way to generate warmth for relieving muscle aches, stiffness, or maintaining warmth in chilly conditions. To use a kairo effectively, activate the pack by shaking or kneading it to start the heating process with air. Once activated, let it gradually warm up after exposure to air. Place the adhesive side of the pack on clothing around the targeted area like the neck, shoulders, back, or abdomen. Adhere to the manufacturer's instructions for the recommended duration of use, typically providing warmth for several hours before cooling down. When the pack has cooled, dispose of it properly according to the manufacturer's guidelines, as specific materials may require special disposal methods. To prevent burns, avoid direct contact of the heat pack with your skin by using it over a layer of clothing.

What are heat packs used for?

Heat packs, also known as kairo in Japanese, are versatile tools offering warmth and comfort for various purposes. Common uses include muscle relief for aches and tension, pain management for conditions like arthritis and menstrual cramps, warmth during outdoor activities, relief from menstrual cramps, stress reduction, and improving circulation. Kairo are effective in promoting muscle relaxation, pain relief, stress reduction, and circulation improvement.

How long do heat packs stay warm?

Kairo or heat packs typically stay warm for varying durations depending on the type and brand. Generally, kairo can provide warmth for around 8 hours, with some types lasting up to 20 hours. The duration of warmth can depend on factors such as the specific product, size of the heat pack, ambient temperature, insulation, and the type of heat pack.

How does heat pack relieve pain?

Heat packs, including kairo, relieve pain through various mechanisms such as increasing blood circulation, promoting muscle relaxation, activating the gate control theory to override pain signals, improving joint flexibility, triggering the release of endorphins, and reducing stress in the affected area. By leveraging these effects, heat packs help alleviate pain effectively. It's crucial to use heat packs correctly to maximize their pain-relieving benefits.

Is it OK to sleep with a heat pack?

Sleeping with a heat pack or kairo is not recommended due to the risks involved, including the potential for burns, overheating, fire hazards, and decreased awareness of temperature. It is safer to use the heat pack according to the manufacturer's guidelines during waking hours and remove it before going to sleep to prevent any safety issues while asleep.

How much is a kairo heat pack in Japan?

The price of a kairo heat pack in Japan can vary depending on the brand, size, quality, and features of the heat pack. Typically, a single Kairo heat pack can cost anywhere from about 25 yen to a few hundred yen in Japan.
 
Prices may also vary based on whether the heat pack is disposable or reusable, the duration of heat it provides, and any additional functionalities it may offer. Additionally, purchasing Kairo heat packs in bulk or as part of a set may affect the overall price. A set of 10 heat packs costs between 263 yen and 405 yen. A box with 30 heat packs can be bought at drug stores starting from about 530 yen.

Written by

I was born and raised in Berlin, Germany and am living in Tokyo, Japan since 2008. I am native in German and English.

I am a cat-mom to three rescue cats and I have a deep love for 90s rock music, kickboxing, history, chocolate and cookie dough, anything pistachio flavored, cats and bats, dragons and vampires and all things creepy-cute.

My favorite book author is Anne Rice. My favorite band is LUNA SEA.

My most recommended Japanese movie is 'Merry Christmas, Mr. Lawrence', featuring David Bowie and Ryuichi Sakamoto.

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