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23 Dec 2019

Buying a hottie or wheat bag for a loved one this Christmas? Here's what you need to know

It's crucial to follow the instructions and safety advice, as they can be a fire risk, plus many microwave brands say not to use them

Microwavable wheat bags and cuddly toys have become popular Christmas gifts, but they can be a potential fire risk if not used correctly.

What's more, many microwave brands say that wheat bags shouldn't be used at all in their microwaves, leaving you at risk of invalidating the warranty by using one.

Many people use wheat bags as an alternative to hot water bottles, as they believe them to be safer (less risk of scalding), and the gentle heat can help to soothe muscular aches and pains.

But they can pose a serious fire risk if used incorrectly, so it's important to follow the instructions and care guidelines carefully to keep yourself and your family safe.

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Why are wheat bags a fire risk?

Wheat bags usually contain grains such as wheat, buckwheat or millet. These have a specific moisture content and excellent insulation properties. Heating the product in a microwave traps this heat and slowly releases it over time.

Wheat bag manufacturers can use the known moisture content of the wheat to give specific guidelines on for how long you can safely heat up wheat bags, heat packs or hotties.

However, if you fail to follow the heating and usage instructions carefully, you could cause the wheat bag to overheat, making it dry and increasing the risk of it igniting. Some common issues include:

  • Not cleaning the microwave before you heat the wheat bag - grease or food left in the microwave could cause hotspots that overheat parts of the pack.
  • Using them in bed - unlike hot water bottles, the wheat in the pack could still be heating up after you've microwaved it and, if placed under bedding, could potentially start a fire.
  • Heating them for longer than specified - if you're used to hot water bottles, you might think the wheat bag isn't hot enough, but overheating it can be dangerous.

Young children or older people with memory issues shouldn't use wheat bags without some sort of adult supervision, as misusing these products could cause serious accidents.

Beware homemade wheat bags

Making your own wheat bags and giving them out as gifts is more risky, as without knowing the exact moisture content of the wheat you use, you'll be unable to provide guidance on exactly how long they can be microwaved for.

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Most microwave brands warn against using wheat bags

Wheat bags are designed for use in your microwave, and indeed this is the only recommended way to heat them.

But when an eagle-eyed Which? member flagged to us that their microwave's manual recommended against using one we discovered that this was the case for most major microwave manufacturers.

Argos, Daewoo, DeLonghi, Morphy Richards, Panasonic and Russell Hobbs all have warnings against using these products in their microwaves, alongside heating things like sponges, slippers, hot water bottles and gel packs.

Some brands have a blanket ban on 'non-food' items, while others also warn against microwaving popcorn. This usually comes down to products having less moisture content, which means they could more easily burn if overheated.

In the case of things like hot water bottles and gel packs, the sealed unit means that pressure can potentially build to unsafe levels inside if overheated.

With this in mind, you need to be aware that even if you heat up your wheat bag according to the retailer's instructions, it could still invalidate your microwave warranty if it develops a fault (although it's more likely to damage the wheat bag than the microwave).

If you're in any doubt or can't find any information in the instruction manual, contact the manufacturer of your microwave to confirm.

What the manufacturers say

We asked Panasonic and Russell Hobbs for comment. We haven't yet heard back from Panasonic, but Russell Hobbs told us:

'We would not suggest the use of wheat bags, we've had something similar before where this caused a failure in the microwave. If a customer uses wheat bags, we believe that the warranty will be voided - this is also stated in some of our instructions.'

Are wheat bags safety tested?

Surprisingly, wheat bag manufacturers are under no legal obligation to adhere to any sort of safety regulations, but there is a voluntary regulation in place.

The safety standard to look out for in the UK is BS 8433:2004. This includes a flammability test and strict rules on the safe usage instructions that should be permanently attached to the wheat bag.

It's worth ensuring that you buy from a reputable retailer and check that the wheat bag conforms to the standard.

How to use wheat bags safely

Reading and sticking to the manufacturer instructions is key (and not using the product if it doesn't have any instructions).

Based on these, here are the golden rules to adhere to if you choose to use a microwavable wheat bag, heat pack or hottie at home:


  • Buy your wheat bag or heat pack from a reputable retailer. Check it conforms to the voluntary safety standard and make sure you can easily contact the retailer if you encounter any issues.
  • Make sure your microwave is clean before heating up wheat bags. The turntable or flatbed should be clean and dry. If your microwave has a turntable, it should turn freely and easily - this prevents hotspots forming.
  • Follow the heating instructions carefully. If your microwave uses more than 1,000W, use a lower power setting.
  • Allow your wheat bag or heat pack to fully cool down on a safe non-combustible surface before attempting to reheat it.
  • Regularly check for signs of damage, including scorch marks or holes in the fabric. If it smells of burning, let it cool down completely and then throw it away, as it's no longer safe to use.


  • Leave your wheat bag unattended while heating.
  • Give wheat bags to babies, elderly people or young children without any adult supervision.
  • Fold up wheat bags to fit them in the microwave. This can create hotspots.
  • Place them under covers to warm bedding. They can continue to heat up and could begin to smoulder or set the covers alight.
  • Heat your wheat bag for longer than the specified time. This could lead to it igniting in the microwave or burning your skin.

More information can also be found on the Cheshire fire service guide to wheat bags.

It's also worth noting that, when first used, wheat bags and heat packs can feel damp, due to their moisture content. This is normal and should ease off after a few uses.

Some manufacturers recommend putting a small cup of water in the microwave with the product once it does dry out, to help prevent overheating.

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