Borax alone does not reliably kill mites in laundry. The most effective factor for killing both dust mites and scabies mites is water temperature, not the cleaning product you add. Water at 55°C (130°F) or higher kills all mites, while lower temperatures fail to eliminate them regardless of what detergent, booster, or additive is used.
What the Research Shows About Borax and Mites
A study published in the Journal of Allergy and Clinical Immunology tested whether laundry products could improve mite kill rates at lower water temperatures. The result was clear: killing at lower temperatures was not enhanced by any of the pure detergents or laundry products tested. Mites survived cool and warm washes no matter what was added to the water. Only temperatures of 55°C (about 130°F) or higher killed all mites consistently.
This means borax, while useful as a general cleaning booster, doesn’t give you a meaningful advantage against mites when used in a standard warm or cold wash cycle. If the water isn’t hot enough, the mites survive. If the water is hot enough, they die regardless of what you add.
What Actually Kills Mites in Laundry
Heat is the reliable mite killer. The CDC recommends using hot water and hot dryer cycles for items exposed to scabies mites, specifying that temperatures above 50°C (122°F) sustained for 10 minutes will kill both mites and their eggs. For dust mites, the threshold is slightly higher at 55°C.
Your washing machine’s “hot” setting typically reaches 49°C to 60°C depending on the model and your water heater setting. If your water heater is set to the common default of 120°F (49°C), a hot wash may fall just short of the kill threshold. Bumping your water heater to 130°F (54°C) before washing mite-contaminated items can make the difference. The dryer matters too. A full cycle on high heat easily exceeds the required temperature, so even if your wash water isn’t quite hot enough, a hot dryer cycle provides a second opportunity to kill surviving mites.
For items you can’t wash or dry on high heat, the CDC notes that sealing them in a closed plastic bag for several days to a week will also kill mites through starvation and dehydration.
Dust Mites vs. Scabies Mites
The type of mite you’re dealing with changes the stakes. Dust mites live in bedding, pillows, and upholstered furniture, feeding on shed skin cells. They don’t bite, but their waste particles trigger allergies and asthma. Washing bedding weekly in hot water is the standard recommendation for keeping dust mite populations low.
Scabies mites are a different concern entirely. These parasites burrow into human skin, causing intense itching and a contagious rash. Laundry protocols for scabies focus on bedding and clothing worn in the previous few days, since scabies mites can only survive off the human body for two to three days. Hot washing and hot drying are the standard approach. The CDC does not recommend borax or any specific additive for scabies decontamination.
Why People Add Borax to Laundry
Borax (sodium tetraborate) is a popular laundry booster that softens hard water, helps lift stains, and can reduce odors. It raises the pH of wash water, making detergent more effective at cleaning. These are legitimate uses, and borax can leave your laundry cleaner and fresher. But cleaner fabric and dead mites are two separate outcomes. The cleaning benefits don’t translate to mite-killing benefits at typical laundry temperatures.
Boric acid, a related compound sometimes confused with borax, is used as an insecticide against cockroaches, ants, and some other pests. It works through ingestion and prolonged contact, which is effective for insects that crawl through treated powder over time. Mites in a washing machine encounter borax only briefly in diluted solution, which is a very different exposure scenario than a dusted surface where pests feed and groom.
Skin Safety With Borax Residue
If you’re adding borax to laundry loads for its cleaning benefits, residue on fabric is generally minimal after a standard rinse cycle. However, borate compounds can irritate skin with prolonged contact. The National Capital Poison Center notes that boric acid causes skin irritation and, in concentrated forms, has caused burns and blisters in at least one documented case involving a young child exposed to pure boric acid powder.
For most adults using borax as directed in laundry, the dilution and rinsing process reduces skin contact to negligible levels. If you have sensitive skin, eczema, or are washing clothing for infants, an extra rinse cycle is a reasonable precaution.
A Practical Laundry Routine for Mites
If your goal is eliminating mites from bedding and clothing, focus on temperature rather than additives. Wash sheets, pillowcases, and blankets weekly on the hottest setting your machine offers. Use a high-heat dryer cycle for at least 10 minutes after washing. For pillows and comforters that can’t handle frequent hot washes, running them through a hot dryer cycle alone still provides significant mite reduction.
You can certainly keep using borax for its cleaning and deodorizing properties. It won’t hurt your mite-reduction efforts, but it won’t replace hot water and a hot dryer as the tools that actually do the job.