Silentnight Anti-Allergy 2.5cm Mattress Topper im Test

The Silentnight Anti-Allergy 2.5cm is a thin hollowfibre mattress topper treated against bacteria and dust mite allergens, sold at Argos in all five UK bed sizes. It is bought for hygiene first and comfort second.

How it is made

The Argos product page describes a 100% polyester cover with a polypropylene reverse and elasticated corner straps, filled with fibres approved by the British Allergy Foundation, the seal run by the charity Allergy UK. The filling contains a biocide, and Argos names the active substance on the listing: dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride. The topper is 2.5cm deep, its removable cover washes at 40°C and can be tumble dried, and Silentnight’s product images state a 2-year guarantee.

Sizes and Argos prices

These were regular prices on 5 October 2026, and the same catalogue numbers are listed on habitat.co.uk, fulfilled by Argos.

What the anti-allergy treatment does, and does not do

Allergy UK’s house dust mite factsheet says that washing at 60°C or above kills mites, while washing at lower temperatures removes the allergen only for a while before the mites produce more. This topper is labelled for 40°C, so the wash alone will not kill mites, and the biocide in the fibre is there to fill that gap. The same factsheet recommends allergen-proof barrier covers that completely enclose the mattress, duvet and pillows. A topper covers only the top of the mattress, so for a mite allergy it works best alongside a proper mattress protector or encasement.

Treated bedding is regulated. Under the GB Biocidal Products Regulation, anyone in the supply chain of a treated article has to give you information about its biocidal treatment on request, free of charge and within 45 days, according to the Health and Safety Executive. If you would rather avoid treated fibre altogether, look for a topper whose label allows a 60°C wash instead.

Feel and who it suits

At 2.5cm the topper softens the surface slightly and adds a washable layer, but it will not change how the mattress supports you. We rate it medium soft, 4 on a 10-point scale. It suits allergy sufferers, guest beds and children’s rooms where easy washing matters more than depth. Argos buyers rated it 4.6 out of 5 from 1,050 reviews in October 2026. Our Argos topper comparison sets it against the deeper toppers in the range.