Horse fly repellent is one of those searches people make halfway through a hot walk, usually with a throbbing ankle and a suspicion that nothing they packed is going to help. The honest answer is less tidy than a product page would like. Horseflies are not mosquitoes, most official repellent guidance is written around mosquitoes and ticks, and the research on horseflies is thin. This guide sticks to what the NHS and the published studies actually say: what a horsefly bite is, which precautions have some evidence behind them, what to do if you get bitten, and where a skincare brand like ours does and does not fit.
What makes a horsefly bite different
Most UK bites are a nuisance. A horsefly bite can be a bigger deal. The NHS describes horsefly bites as "large, painful and may bleed", and says they often become infected (NHS, Insect bites and stings, page last reviewed 1 June 2023). That puts them in a different category from the small, raised, itchy bump the same page describes for a mosquito.
The reason is how the fly feeds. A 2026 clinical review in the journal Cutis explains that female horse flies pierce the skin, inject anticoagulant saliva and suck the blood, which can cause minor skin reactions such as hives and papules at the bite site. In severe cases the authors say bites can result in anaphylaxis, and they note that horse flies can transmit tularemia (Vora and Rohr, Cutis, 2026, abstract read). Tularemia is not a typical UK worry, so read that as background rather than a reason to stay indoors. The practical point is simpler: the bite breaks the skin properly, so it deserves a clean-up and a watchful eye.
If you want the wider picture of what else bites in a British summer, our UK biting insects field guide covers midges, horseflies, ticks, fleas and mosquitoes side by side.
Does a horse fly repellent actually work?
Here is where the evidence gets thin, and it is worth being plain about it.
The two best known repellent lists, from the US CDC and the US EPA, are built around mosquitoes and ticks. The CDC's mosquito prevention page tells you to use EPA-registered insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, PMD or 2-undecanone (CDC, Preventing mosquito bites, page dated 28 August 2024). The EPA says a registration number means the company supplied information on a product's safety and its effectiveness against "mosquitoes and/or ticks" (EPA, Find the Repellent that is Right for You, last updated 8 September 2026). Neither page names horseflies. So a registered repellent is not automatically a proven horse fly repellent, and a label that says nothing about flies is not making that promise.
What does exist is a small amount of horse-focused research and one clinical review. The Cutis review concludes that exposure to horse flies can be minimised through protective clothing, topical repellents and traps. That supports using a repellent as one layer, though it is an abstract-level summary, not a ranking of products.
The most direct trial we found tested a repellent on horses rather than people. Researchers in Hokkaido, Japan, compared horses with no horsecloth, a plain horsecloth and a horsecloth impregnated with icaridin (the ingredient also known as picaridin). They report that the icaridin cloth significantly reduced the number of horseflies, that the plain cloth did not, and that the icaridin cloth was "more effective for repelling horseflies than the use of physical barriers alone" (Suganuma et al., Acta Tropica, 2024). It was six horses at one riding club, and the authors themselves recommend more research with more animals. Read it as a hint that picaridin is worth knowing about, not as a verdict for your own legs.
If you want to know how picaridin and DEET behave on skin, our explainer on picaridin versus DEET on your skin covers both.
What the research says about colour and warmth
Some of the more interesting research is not about sprays at all. A 2022 study in Scientific Reports tested tabanids, the horsefly family, on a host-imitating target. The authors found that horseflies spent more time walking on thin black stripes than on the surrounding grey, but only in sunshine, because the stripes were warmer. They say this is "consistent with the flies' well-documented attraction to warmer temperatures" (Takacs et al., Scientific Reports, 2022). The Hokkaido horse study reported something similar from the other direction: lighter-coloured horses had fewer fly attacks and fewer avoidance actions than darker-coloured horses.
Neither study was done on a person in a field in Dorset, so we would not promise that a pale shirt will save you. But it fits the common-sense advice: if you have a choice, wear lighter clothes, and do not assume a dark, sun-warmed top is neutral.
How to avoid horsefly bites on a summer walk
The NHS Cornwall and Isles of Scilly integrated care board, in guidance on bites it describes as common "at this time of year", puts it in one line: if you are going to be outside, "apply insect repellent and cover up to protect yourself" (NHS Cornwall and Isles of Scilly ICB, 1 August 2024). Putting that together with the studies above, a sensible routine looks like this:
- Cover your legs and arms. Horsefly bites are on the NHS's list of larger, more painful bites, so a physical barrier is worth more than a hopeful spray.
- Choose lighter colours where you can, given the temperature and colour findings above.
- Use a skin repellent as a second layer, and follow its label. The EPA says to apply repellent only to exposed skin and clothing, never under clothing, not near eyes and mouth, and never over cuts, wounds or irritated skin (EPA, Using Insect Repellents Safely and Effectively, last updated 10 November 2025).
- Do not trust a mosquito label to cover flies. If the label does not name horseflies, the claim has not been made.
If you are applying anything to your face before heading out, our note on using insect repellent on your face covers the awkward spots.
If a horsefly gets you anyway
Bites are not always avoidable, so the aftercare matters. The NHS says insect bites are not usually serious and get better in a few days, but can become infected or cause a serious allergic reaction. For the bite itself, it suggests washing the skin with soap and water, putting a cold cloth or ice pack wrapped in a cloth on any swelling for at least 20 minutes, and not scratching it. It also says antihistamines can ease itching and a hydrocortisone cream can reduce itching and swelling (NHS, Insect bites and stings).
The NHS says to see a pharmacist if the skin around the bite feels hot or looks red (redness can be harder to see on brown and black skin), if it is painful or swollen, or if there is pus or fluid coming out. A pharmacist can recommend treatments and give the same antibiotics as a GP if the bite is infected. The NHS says to ask for an urgent GP appointment or get help from NHS 111 if symptoms get worse or are not getting better, if you were bitten near your eyes, mouth or throat, if you have tummy pain and are being sick, feel dizzy or lightheaded, or have a high temperature and swollen glands. It says to call 999 for swelling of the lips, mouth, throat or tongue, or if you are struggling to breathe.
For the itch afterwards, our guide on how to stop mosquito bites itching has the same soothing basics, even though the bite is a different one.
Where Misaj fits
Misaj, a Paris based skincare brand, makes Glow Protect, a daily skincare cream. Its Glow Protect product page says it "combines hydration, skin barrier support and botanical mosquito protection in a single cream designed to be worn daily." That wording is about mosquitoes. The page does not mention horseflies, so this guide makes no claim about Glow Protect and horseflies.
The takeaway
Horsefly bites hurt more than most UK bites, and the NHS notes they are often infected. The evidence for any specific horse fly repellent is limited: the official lists cover mosquitoes and ticks, one horse study supports picaridin as a layer, and the clinical review points to clothing, repellents and traps together. Cover up, go light where you can, read the label, and know when to see a pharmacist or call 111. For the other half of the summer calendar, our midge repellent guide for Scotland looks at the smaller biter.
Frequently asked questions
What is the best horse fly repellent?
There is no ranking we can honestly give. The CDC and EPA repellent lists refer to mosquitoes and ticks, not horseflies. One 2024 trial on horses found an icaridin-impregnated horsecloth reduced horsefly numbers more than a plain cloth. Check the label and use it with clothing.
Do mosquito repellents work on horseflies?
Not necessarily. The EPA describes registration in terms of effectiveness against "mosquitoes and/or ticks". If a label does not name horseflies, it has not claimed protection against them.
Why do horseflies bite so painfully?
A 2026 Cutis review says female horse flies pierce the skin, inject anticoagulant saliva and suck blood. The NHS describes the resulting bites as large, painful and likely to bleed.
What colour clothing do horseflies avoid?
Research is limited. A 2022 study found horseflies spent more time on warmer black stripes in sunshine, and a 2024 horse study found lighter-coloured horses had fewer fly attacks. Neither was done on people, so take it as a tip, not a guarantee.
When should I get a horsefly bite checked?
The NHS says to see a pharmacist if the skin feels hot, looks red, is painful or swollen, or has pus coming out. It says to get urgent help from NHS 111 or a GP if symptoms are getting worse or you have signs such as dizziness, a high temperature or swollen glands.
Does Glow Protect repel horseflies?
Its product page describes botanical mosquito protection and does not mention horseflies, so we make no claim about them.
Sources
Fetched 2026-10-26.
- NHS, Insect bites and stings, page last reviewed 1 June 2023 (horsefly bites, aftercare, when to seek help). https://www.nhs.uk/conditions/insect-bites-and-stings/
- NHS Cornwall and Isles of Scilly ICB, Bitten or stung by an insect?, 1 August 2024 (prevention advice). Page link
- Vora PS, Rohr B. Horse Flies: Identification, Bite Reactions, and Clinical Management. Cutis, 2026. doi:10.12788/cutis.1398. PubMed 42594391 (abstract via Europe PMC).
- Suganuma K et al. Repellent activity of icaridin-impregnated horsecloth against horse flies. Acta Tropica, 2024. doi:10.1016/j.actatropica.2024.107485. PubMed 39616695 (abstract via Europe PMC).
- Takacs P et al. Sunlit zebra stripes may confuse the thermal perception of blood vessels causing the visual unattractiveness of zebras to horseflies. Scientific Reports, 2022. PubMed 35927437, PMC9352684 (abstract via Europe PMC).
- CDC, Preventing mosquito bites, page dated 28 August 2024 (registered repellent ingredients). https://www.cdc.gov/mosquitoes/prevention/index.html
- EPA, Find the Repellent that is Right for You, last updated 8 September 2026. https://www.epa.gov/insect-repellents/find-insect-repellent-right-you
- EPA, Using Insect Repellents Safely and Effectively, last updated 10 November 2025. https://www.epa.gov/insect-repellents/using-insect-repellents-safely-and-effectively
- misajskin.com, Glow Protect product page (brand wording quoted verbatim, checked 2026-10-26). https://misajskin.com/products/glow-protect
The CDC page returned HTTP 403 to curl this run and was read through a fetch tool that returned the page text. The Cutis article is behind a publisher site, so only its abstract was read; nothing is attributed to it beyond the abstract.