Does Freezing Kill Bed Bugs? Times, Limits and Safe Use

Yes, freezing kills bed bugs, but only if the item stays cold enough for long enough. Laboratory work shows that a freezer at -17.8°C needs at least 3.5 days to kill every life stage. The NHS advises 2 to 3 weeks for items that cannot be washed. Freezing suits small things such as shoes, books and soft toys. It cannot treat a bed, a sofa or a room.

What the tested numbers say

For example, researchers at the University of Minnesota and Rutgers University exposed all life stages to cold. They found that bed bugs are freeze intolerant, which means they die when their body fluids freeze. However, they resist cold well. Their supercooling points ranged from -21.3°C to -30.3°C, and eggs reached the lowest figure.

Time still matters as much as temperature. The model estimated survival at temperatures above -12°C even after a week of continuous exposure. Below -15°C, the study says 3.5 days is enough to control all life stages. Below -20°C, 48 hours or less is enough. For home use, the authors recommend -17.8°C (0°F) for a minimum of 3.5 days.

Note that sublethal cold did not stop survivors feeding afterwards. A short chill therefore does nothing useful, and may leave a hungry survivor.

Why the NHS gives a longer time

The NHS says to put items that cannot be washed in a plastic bag and into the freezer for 2 to 3 weeks. That is far longer than the laboratory minimum. The longer time is likely a safety margin. A home freezer door opens, the defrost cycle warms the air, and few people measure the real temperature.

Similarly, the Minnesota authors made the same point. They warned that freezers with large defrost cycles are not recommended, because the temperature can rise above freezing. They also said homeowners should follow the model times rather than shorter ones. In their freezer tests, the results varied with how much the temperature swung.

The item has to get cold all the way through

In particular, a study from the University of Sheffield tested laundry. It found that freezing at -17°C for at least 2 hours killed all life stages. However, 2.5 kg of loosely packed dry laundry took about 8 hours to reach -17°C. The clock starts only when the centre of the item reaches the target.

The European Code of Practice makes the same point. Dense items hold their temperature longer, so larger or denser items may take days to cool through. For that reason, give a thick bag of clothes more time than a single shoe. Our post on washing and drying covers the easier option for fabrics that can take a hot wash.

How to freeze an item safely

First, seal the item in a plastic bag. The Minnesota authors say bagging stops bugs escaping into the freezer and protects the item from condensation. The European Code of Practice suggests sealed plastic boxes that stay sealed for the whole treatment.

Second, check the freezer temperature with a thermometer. Third, leave the item for the full time, and do not open the bag early. The Code also warns that freezing causes some condensation, so moisture-sensitive items may not suit it. Check the maker’s advice for electronics before you try.

Finally, bring the item out and keep it sealed until you have checked it. Cold has an anaesthetic effect on insects, so a bug can look dead and wake up as it warms. That is a reason to give the item its full time rather than judge it by eye.

What freezing cannot do

Freezing cannot treat furniture, floors or walls. It also cannot stop reinfestation from untreated parts of the home. Treatment of a whole room needs methods such as heat treatment, covered in our post on how long heat treatment takes. Our page on steam treatment explains the surface option.

Similarly, winter weather is not a substitute. The Minnesota model shows bugs surviving above -12°C for a week. The Code adds that development stops below 13°C, so a cold room slows bugs without killing them. Moving a bag outdoors in cold weather is therefore unreliable.

Freezing is also only one piece of a plan. The British Pest Control Association says most infestations need a combination of methods, which can include cold. See our guides to DIY treatment and treatment comparison for how it fits.

Where freezing fits in a plan

Use freezing for the small, dry, heat-sensitive things you cannot wash. Then monitor the bed with interceptor traps to see whether activity is falling. If you have just returned from a trip, read our post on avoiding bed bugs after travel before you unpack.

Afterwards, the signs a treatment has worked help you judge progress. Our after-treatment guide explains what to record. The NHS says it is very difficult to get rid of bed bugs yourself, so contact your local council or a pest control service if bugs persist. Read the safety and labels guide before using any product.

Does freezing kill bed bugs?