Dust mites – measuring about a quarter of a millimetre long and invisible to the human eye – are the bane of many people’s lives.
It is estimated that up to one in three of us is affected by dust mite allergic rhinitis, or dust mite allergy. This is essentially inflammation of the inside of the nose caused by the immune system reacting to a protein in dust mite droppings – leading to congestion, itchiness in the nose, throat or eyes, sneezing, a reduced sense of smell and difficulty sleeping. It can also worsen symptoms for many people who have asthma or eczema.
At this time of year, when it’s cold and we’re trapped at home with the heating on and windows shut, they’re having a field day in bedding, cushions, curtains, carpets and other soft furnishings.
Dust mites feed on dead human skin cells partially digested by mould and thrive in warm, humid environments.
But you can take steps to reduce your exposure, which can have a significant impact on symptoms.
‘House mite allergic rhinitis is very common, but knowing what to do can be confusing,’ says Dr Glenis Scadding, an honorary consultant physician in allergy and rhinology at University College London Hospitals NHS Foundation Trust.
‘Methods to reduce house dust mites don’t benefit everyone in the same way – and doing one thing rarely works, you have to take multiple measures at once.’
The internet, as ever, is flooded with suggestions – from spraying carpets with vodka to putting your duvet in the freezer. We asked leading experts to assess how effective some of these strategies really are…
At this time of year, when it’s cold and we’re trapped at home with the heating on and windows shut, dust mites are having a field day in bedding, cushions, curtains, carpets and other soft furnishings
Delay making your bed
Dust mites absorb moisture from the air through their skin, and so are reliant on humid conditions – and they love a warm bed where you toss and turn for hours, shedding skin cells.
Airing your sheets, mattress and duvet regularly causes them to die off. ‘The best thing is to fold over the duvet and have the sheets exposed and allow the mattress to air for a few hours during the day,’ advises Dr Scadding.
‘At the same time, have a window open and ventilate your space. Vacuuming your mattress every few weeks can also help remove skin cells and mites.’
Spray tea or alcohol
Social media hacks for reducing the effects of dust mite allergens include spraying alcohol or tea on bedding.
It’s thought the tannic acid in tea acts as a ‘denaturing agent’ – changing the structure of the allergen (i.e. dust mite faeces) – so our immune system doesn’t respond to it in the same way.
‘There is no robust science behind this,’ says Amena Warner, head of clinical services for Allergy UK. Indeed, one study testing benzyl benzoate moist powder, an acaricide (pesticide) containing 3 per cent tannic acid, found dust mite killing effects didn’t last long and were not dramatic.
Some online videos recommend spraying mattresses, pillows and curtains with vodka – the theory is alcohol kills mites by breaking down their soft exterior membrane and drying them out.
‘There’s no clear science behind this either and it would smell awful,’ says Amena Warner.
Open the windows
On TikTok ‘house-burping’ – where you fully open windows for ten to 15 minutes to let out fetid air and let in fresh, no matter how cold it is – has become a popular trend and, according to experts, there are good reasons for it, especially if you have allergic
rhinitis. ‘It’s really important if you’re struggling with allergies to get the indoor temperature down [to around 20c] and reduce humidity,’ says Amena Warner.
‘At this time of year, in particular, we cook, shower, dry clothes – and have the heating on – while doors and windows stay sealed shut.’
Allergy and rhinology expert Dr Glenis Scadding says: ‘Methods to reduce house dust mites don’t benefit everyone in the same way – and doing one thing rarely works, you have to take multiple measures at once’
If you can’t open a window, use the trickle-vents in double-glazing or extractor fans to allow fresh air to circulate – for hours, or all the time, if necessary.
Amena Warner recommends maintaining indoor humidity at less than 50 per cent (but more than 30 per cent) and using a hygrometer, a device measuring water vapour [humidity] in the air to check – so that mites don’t proliferate so quickly and you’re exposed to less of the allergen.
Do a weekly hot wash
Female dust mites can lay 100 eggs in their lifetime (between 65 and 100 days) and each mite produces around 20 bits of faecal matter (the allergen) a day, so the amount of allergen escalates more quickly if you don’t remove the eggs. To actually kill the dust mites and get rid of their eggs you need a hot wash (i.e. at least 60c), says Amena Warner. She suggests washing sheets, duvet covers, pillow cases and throws every week or two; pillows every two to three months; and duvets every year.
Steam the car
Videos of people steam cleaning cars, sofas, mattresses and headboards to kill mites are widely shared on social media – and it should work.
Dr Scadding explains: ‘Applying high temperature steam [around 120c] under pressure denatures molecules – meaning they fall apart and are no longer recognised by the body as allergens.
‘It is a very good way of cleaning your house and things that are difficult to wash, such as curtains, carpets and car interiors.’
Try it every six weeks or when symptoms are pronounced. ‘People forget you can get a lot of dust mites in cars and, if you drive a lot, steaming every now and then can help,’ says Dr Scadding.
Freeze cushions and toys
‘It seems crazy to suggest people stuff their pillows in their freezer – but it does work, because dust mites die at temperatures below freezing,’ says Amena Warner.
She recommends putting children’s soft toys that cannot be washed at 60c in a plastic bag in the freezer for at least 12 hours every month – then washing them at the recommended temperature, to remove mites and their faeces if the child is dust mite allergic (and avoid bunk beds where allergens can fall on them from above).
Use ultraviolet vacuum
The dusty (and disgusting) contents of dust mite vacuums – typically handheld devices that emit ultraviolet (UV) light and hot air at 60c, while tapping (to dislodge dust mites and their allergen to better suck them up) – are another popular theme in social media videos.
These devices can be of some use, says Dr Scadding. ‘Researchers have found that UV light can disable airborne allergen protein, including from dust mites, by altering their protein structure.’
But you’d need to hold the UV light on one spot for several minutes to kill an adult dust mite, she adds – which isn’t practical as it would take you hours then to adequately do a carpet or mattress.
As for regular vacuum cleaners, these tend to stir up dust and other particles, making them easier to inhale – and worsening symptoms of allergic rhinitis.
Dr Scadding recommends wearing a mask while vacuuming or buying a vacuum cleaner with a highly sensitive filter able to pick up more of the smallest particles (look for a HEPA stamp, which means it can trap allergens as small as 0.3 microns).
Allergy UK has an independently tested, approved list of anti-allergy vacuum cleaners.
Plug in a blanket
Online forums suggest leaving an electric blanket on for 15 minutes on a high heat setting can kill off mites, by reducing humidity in bedding by drying it out.
‘There is some evidence for this – one study, in the Journal of Allergy and Clinical Immunology in 1988, found an electric blanket could more than halve the concentration of mites when used consistently over a year,’ says Dr Scadding.
‘But whether this translates into a reduction of symptoms in those with allergic rhinitis is unlikely, as it doesn’t get rid of the actual allergen – you’d need to vacuum or damp wipe it afterwards.’
Opt for chemical spray
There are two popular options: sprays containing acaricides (a pesticide that kills mites and ticks) or cypermethrin (a more heavy-duty insecticide used in agriculture), which can be used on rugs, mattresses, pillows and other soft furnishings.
‘They kill dust mites,’ says Dr Scadding, ‘but these chemicals act on us, too – on cells lining our skin and respiratory tracts, causing irritation’.
She suggests safer alternatives such as steam cleaning or washing allergens away.
Go ultrasonic
Plug-in devices (costing around £20) are claimed by their manufacturers to reduce dust mites with ultrasonic sound waves (inaudible to humans) that disrupt feeding and breeding cycles.
Evidence is lacking, says Dr Scadding.
A 2021 study in the Journal of Allergy and Clinical Immunology that looked at the effectiveness of two devices over three weeks showed they failed to reduce live dust mite numbers or allergen levels in carpets.
Use anti-allergy bedding covers
Anti-allergy mattress, duvet and pillow covers are evidence-based and widely recommended online for use against mites
Anti-allergy mattress, duvet and pillow covers are evidence-based and widely recommended online for use against mites – you’re meant to put a regular sheet or pillow case over the top.
‘They are made from such tightly woven, non-porous fabrics that dust mites and their faecal matter can’t travel through, creating a physical barrier that reduces the amount of allergen you come into contact with,’ says Amena Warner, head of clinical services for Allergy UK.
‘These can be effective at reducing house dust mite populations where you sleep – but check the manufacturers’ recommendations on washing them as some have been sprayed with anti-fungal or biocidal agents that might be reduced on a hot wash.’
And as skin cells land on these covers and provide mite food, they should be damp wiped when the bedding is changed.