On 1 July 2026, Which? lab-tested 12 mosquito repellents. The £4 supermarket DEET spray lasted longest; the £20 'natural' one gave essentially no protection at the two-hour mark. The same week, 60 Millions de Consommateurs in France and Consumer Reports in the US reached the same verdict: what protects you is the active-ingredient concentration and the re-application interval, not the price and not the word on the front of the pack.
The repellent that lasted longest in Britain's latest lab test cost £4. The one that gave up first cost £20, and it was the one sold as "natural."
Which?, the UK's largest consumer group, tested 12 mosquito repellents and published the results on 1 July 2026. The longest-lasting was a supermarket own-brand DEET spray. The £20 "natural" product offered essentially no protection at the two-hour mark. Same shelf, five times the price, and backwards on the single thing anyone buys a repellent to do. Within the day the finding was in the Telegraph, the Guardian and the Daily Mail.
Three labs, three countries, one answer
A £4 spray beating a £20 one would be a good story on its own. What makes it more than a story is that two other laboratories, in two other countries, had just said the same thing.
On 24 June, 60 Millions de Consommateurs ran its 2026 test in France and reported the same shape of result: few genuine innovations in the category, effectiveness all over the map, and no miracle product anywhere on the shelf. In the United States, Consumer Reports published its 2026 roundup, testing lotions, sprays, wipes and plant-based formulations against live mosquitoes; its list is now the reference American shoppers reach for. Three labs, three countries, three sets of rules, three different baskets of product. They do not share methods, they do not share data, and they did not coordinate. They arrived at one answer.
The answer is that a repellent protects you through two levers only: the concentration of its active ingredient, and how often you re-apply it. Not the price. Not the word on the front of the pack.
The information was on the back of the can
The £4 spray is not a miracle either. It is DEET, at the concentration printed on the can, doing for as long as that concentration predicts exactly what DEET does. The £20 product is a plant-based formulation whose selling point is not what is in it but what is written on it. Its active-ingredient profile was never the lever. The label was.
This is where the category earns its scepticism, and it pays to be exact about why. The active ingredients in these sprays are regulated as biocidal products, held to a standard for what they contain and how their protection may be described. The adjective "natural" clears no such bar. It is a marketing word, not a regulated health claim, and it is not the thing that keeps a mosquito off your arm. The honest information was on the back of the can. The advertising was on the front.
Hear the right lesson, though, not the loud one. This is not natural bad, synthetic good. DEET and picaridin are synthetic, and the same consumer labs confirm they work at the concentrations they list. The point is narrower and far more useful: the word on the front tells you nothing about the performance, and three labs have just made that expensive to ignore.
The layer that cannot be marketed at you
Read the back of the can and you are still buying a layer with limits. Every spray fades on a clock. Every dose has a concentration. And the mosquito is not standing still: a 2026 European mosquito, raised under years of steady DEET pressure, is not the insect a repellent was validated against in the 1990s. The chemistry that worked then is a moving target now.
One layer does not fade, does not need a dose, and makes no claim it cannot keep. A mosquito net, treated or untreated, fitted properly over a bed. A window screen kept in good repair. A long sleeve after dark. None of these has a re-application interval. None has a price tier that quietly correlates with a lie. You pay for them once, and they do not depend on you reading the small print correctly. It is also the layer that public-health guidance has leaned on the longest.
This is the durable layer. The spray, even the good £4 one, is the supplement. At Mosticare we put the two in that order, and the evidence this fortnight is the cleanest case for that ordering the market has handed us in years.
What to take to the shop
Three moves, in the order the evidence puts them. Read the back of the can, not the front. Apply on the clock the label gives you, not at the first bite. And put something physical between you and the night-biting mosquito, because it is the only layer on the list that cannot be marketed at you.
The £4 spray won because its active ingredient was on the back of the can. The £20 spray lost because its argument was on the front.
Sources
- Which? · Buzzkill: trendy £20 mosquito repellents fail Which? testing · 1 July 2026 · https://www.which.co.uk/policy-and-insight/article/buzzkill-trendy-20-mosquito-repellents-fail-which-testingbut-4-supermarket-spray-lasts-for-hours-aQoTp4O4JRxx
- 60 Millions de Consommateurs · Antimoustiques 2026 : les sprays répulsifs vraiment efficaces · 24 June 2026 · https://www.60millions-mag.com/sante-bien-etre/article/antimoustiques-quels-sont-les-repulsifs-vraiment-efficaces-20260624/
- Consumer Reports · Insect repellent buying guide (2026 lab test) · June 2026 · https://www.consumerreports.org/health/insect-repellent/buying-guide/
- European Chemicals Agency · Biocidal Products Regulation · https://echa.europa.eu/regulations/biocidal-products-regulation/understanding-bpr
- World Health Organization · Personal protection against mosquitoes · https://www.who.int/publications/i/item/WHO-HTM-NTD-VEM-2017.02
Published 2026-07-03 · Mosticare Editorial