UK summers bring a reliable cast of troublesome insects. Stable flies, horseflies, midges and black flies are active from late spring through to early autumn, overlapping so there is rarely a clear window when your horse gets a proper break.
When fly pressure is high, you see it straight away: stamping, tail swishing, head tossing, skin twitching and a horse that simply will not settle to work or rest comfortably. That is the point at which fly spray earns its place in the grooming kit.
Fly spray is not a standalone solution, and the yards that manage flies best treat it as one layer in a wider plan. Physical barriers, including fly rugs and fly masks, cover large areas of skin that no spray can protect for a whole day. Good yard management, regular muck removal and avoiding turnout near standing water reduce the fly population around your horse before it even gets near the coat.
Sensible turnout timing around dawn and dusk makes a real difference for midges specifically. But for the skin that rugs and masks cannot cover, the right fly spray, applied correctly and regularly, makes a daily difference to your horse's comfort.
Browse our full range in our fly repellents, sweet itch and lice collection.
Understanding what is in the bottle: repellents, insecticides and combinations
Not all fly sprays work the same way, and the distinction matters when you are choosing.
A repellent makes the horse less attractive to insects by interfering with how they detect hosts, blocking the odour and chemical cues that bring flies in for a landing. It deters insects but does not kill them.
An insecticide kills or disables insects on contact, reducing the number that can bite. Many of the most effective products on the market combine both: a repellent active to reduce landings, with an insecticidal active to deal with those that make it through.
The label also matters in a regulatory sense. Fly sprays sold in the UK must be registered under biocide and pesticide regulations and carry a valid HSE number. That registration means the active ingredients have been assessed for safety and efficacy under UK rules.
Products without an HSE number, including many home-mix oil recipes, carry no such assurance and their performance is impossible to verify.
DEET, Icaridin or natural: which type suits your horse?
There are three main categories of fly repellent available in the UK. Your choice will depend on the level of fly pressure on your yard, your horse's skin sensitivity and how often you are realistically going to reapply.
DEET-based fly sprays
DEET (N,N-diethyl-m-toluamide) is a synthetic repellent that works by scrambling the odour signals insects use to find horses. It is strong and relatively long-lasting, which is why it remains the default choice when fly pressure is serious or horseflies are a problem.
Most equine DEET sprays are formulated at around 20%, which sits within UK regulatory limits for direct animal application and gives solid, reliable protection during rides, hacking and longer turnout.
DEET is worth patch testing before first use on fine or sensitive skin. Keep it away from eyes, nostrils, broken skin and direct contact with leather or synthetic tack. Some riders find it leaves a slightly greasy feel, which is one reason Icaridin has steadily gained ground as an alternative.
Icaridin: a strong DEET-free option
Icaridin, also known as Saltidin or Picaridin, is a modern synthetic repellent developed as a DEET alternative. It works in a similar way, blocking the insect's ability to detect its host, but tends to be less greasy and less strongly scented, and is often better tolerated on sensitive skin.
Field studies in people show Icaridin can match DEET for protection time against many biting insects, and it has built a strong reputation in equine use for exactly the same reason.
Leovet Power Phaser is the product that has put Icaridin on the map for UK horse owners. The formula contains 20% Icaridin (Saltidin), has been independently tested to show up to seven hours of protection, and consistently earns strong reviews from riders who need serious performance without DEET.
Natural and plant-based fly sprays
Plant-based repellents use actives such as citronella, garlic, geranium, lemongrass, PMD (p-menthane-3,8-diol) and essential oil blends to mask the horse's scent and deter insects. They tend to need more frequent reapplication than synthetic options in heavy fly conditions, and natural does not mean risk-free: concentrated essential oils can irritate sensitive skin just as much as a synthetic, so patch testing is still important.
That said, some plant-based products carry proper HSE registration and have been assessed to a genuine standard. These are a meaningful step up from unlabelled home mixes and a real option for owners who prefer to avoid synthetic actives entirely, particularly for horses with sensitive skin or sweet itch.
Spray, gel or roll-on: choosing the right format
Format matters as much as formulation, because it determines where you can effectively apply the product and whether your horse will tolerate it.
Sprays are fast and practical for covering the body, neck, hindquarters and chest. The most common mistake is under-applying. A few light squirts along the topline covers a fraction of the areas where flies cause damage.
Work on a clean, dry coat and apply until the coat is evenly damp, covering the belly, inner thighs, chest, sheath or udder area, and the legs as well as the topline.
Gels and creams adhere better to awkward areas: the belly line, sheath, udder, between the legs, around the tail dock and inside the ears. They do not drift in wind, they are silent, and they give you precise control near sensitive spots.
Many riders use a spray for the main body and a gel for the areas where flies do their worst.
Roll-ons are the most precise format of all: useful for a fine line around the jaw, along the blaze, around the edge of the ear or along tack contact lines where overspray could damage leather.
Very practical at a show when you want a small, controllable top-up in your grooming bag.
For horses that hate being sprayed, the answer is usually not to persist with direct spraying. Spray product onto a cloth away from the horse and wipe it on by hand. Start with low-pressure areas, keep sessions short, reward generously and introduce the spray bottle gradually over several sessions before you try misting directly.
Our top picks by use case
Best for heavy fly pressure and horseflies
When flies are relentless and standard options are not holding, a strong DEET-based repellent is the right call.
NAF OFF DEET Power Spray
NAF's most powerful repellent, designed for all-day protection against flies and biting insects. The DEET formula delivers the intensity needed when horseflies are a persistent problem. Available in 750ml spray and 2.5 litre and 5 litre refill sizes, which makes it cost-effective for yards running multiple horses through a long summer.
Best for: horses near cattle or muck heaps, horses in areas with serious horsefly pressure, owners who need a proven DEET-based option in a useful refill range. Shop NAF OFF DEET Power Spray
Carr & Day & Martin Flygard Extra Strength
A 20% DEET formula from one of equestrian's most established names. Recommended by the brand for twice-daily application to maximise protection, available in 500ml and 1 litre.
Best for: horses in regular work where strong, all-round repellent cover is a daily requirement. Shop Carr & Day & Martin Flygard Extra Strength
Best DEET-free option for regular work
Leovet Power Phaser Fly Repellent Spray
One of our bestsellers and one of the most consistently recommended fly sprays by UK riders. The 20% Icaridin (Saltidin) formula has been independently tested by the Swiss Tropical Institute and shown to offer up to seven hours of protection. It is designed to remain effective even when horses sweat, which matters considerably on warm UK summer days.
Available in 500ml and 2.5 litre refill sizes.
Best for: horses in regular work, hacking, schooling and competing, where owners want genuine performance without DEET. Shop Leovet Power Phaser Fly Repellent Spray
Best for sensitive skin and sweet itch horses
Barrier Animal Healthcare Enhanced Formula Fly Repellent
100% natural, non-sting and designed specifically for horses with sensitive skin or sweet itch reactions. Unusually, it can be applied directly to sore or exposed areas to soothe irritation from midge bites, rather than just being used at the margins. It contains no citronella, vinegar or prohibited substances, carries HSE approval, and is suitable for use under FEI and BHA competition rules.
Available in 500ml trigger, 500ml refill and 5 litre refill.
Best for: sweet itch horses, horses with fine or reactive skin, and any situation where repellent needs to be applied near or on damaged skin. Shop Barrier Enhanced Formula Fly Repellent
Barrier Animal Healthcare Super Plus Fly Repellent
The stronger counterpart in the Barrier range. A super-strength 100% natural formula with avocado to condition the coat, it works against blood-sucking and nuisance flies including midges, bots and horseflies. HSE approved and free from prohibited substances.
Available in sizes from 500ml up to 5 litre.
Best for: owners who want a natural, competition-safe formula but need something with real strength, particularly on yards where midge and horsefly pressure is high. Shop Barrier Super Plus Fly Repellent
Best for spray-shy horses and precise application
Leovet Power Phaser Gel
The same 20% Icaridin formula as the spray, in a thicker gel format. No aerosol noise, no mist, no drift: apply with your hand, a sponge or a cloth directly onto the areas that need it. Particularly effective on the face, ears, belly line, inner thighs and any horse that reacts strongly to the sound or sensation of spraying.
Up to seven hours of tested protection.
Best for: horses that hate being sprayed, and for topping up targeted areas, particularly the face and sensitive spots, between full-body applications. Shop Leovet Power Phaser Gel
NAF OFF Extra Effect Gel
A DEET-free, plant-based gel using garlic and essential oils. The 750g format is easy to apply by hand to key bite zones and is a good option for horses that are sensitive to the smell or sensation of aerosols.
Best for: horses that are spray-shy and whose owners prefer a natural, DEET-free formulation for everyday use. Shop NAF OFF Extra Effect Gel
Everyday options and good-value repellents
Lincoln Natural Fly Repellent
Uses PMD (p-menthane-3,8-diol), a plant-derived active with HSE registration, in a water-based, non-flammable formula. A well-regulated, gentle everyday option for owners who want an HSE-approved natural repellent without going to a synthetic. Shop Lincoln Natural Fly Repellent
Nettex Equine Fly Repellent Advanced
A higher-strength everyday spray available in 500ml and 2 litre refill, well priced for owners who get through product quickly during peak season. Shop Nettex Equine Fly Repellent Advanced
A note on stable and yard premises sprays
One product that appears in many "best fly spray" round-ups deserves an honest clarification. Farnam Tri-Tec 14 is a powerful cypermethrin-based insecticide with a strong reputation for killing multiple fly species and long-acting residual protection.
However, in the UK its HSE licence (number 9215) covers use on premises around horses, such as stables and shelters, not direct application on the horse. Using it on the horse itself is off-label and at the owner's risk. If you want Tri-Tec 14 in your fly control plan, use it as a stable and yard spray and pair it with a separately licensed on-horse repellent.
How to apply fly spray so it actually works
The most common reason fly spray underperforms is not the product, it is the application.
Start with a clean, dry horse. Mud, sweat and loose hair all reduce how well any spray adheres to the coat. Shake the bottle before use, since actives can settle between applications.
Apply until the coat is evenly damp, not dripping, and prioritise the areas where flies do the most damage:
- Belly, inner thighs, sheath and udder
- Chest and lower neck
- Around the dock and top of the tail
- Legs, particularly from the knee and hock down where stable flies bite repeatedly
For the head and face, never spray directly at the face. Spray onto a cloth and wipe carefully around the jaw, cheeks and outer ear, staying well clear of eyes, nostrils and lips. A gel or roll-on gives better control for the face and ears.
If your horse is going out in a fly mask, you may need very little topical repellent on the head at all.
If your horse sweats heavily during work or gets caught in a shower, assume the protection has been significantly reduced and reapply once the coat is dry.
How long does fly spray actually last in UK conditions?
The honest answer is: less than the label suggests, most of the time. "Up to seven hours" or "up to 14 days" figures are derived from controlled testing conditions.
On a real UK yard in July, with showers, warm temperatures and horses sweating through exercise and turnout, most everyday sprays give a few hours of solid protection and benefit from reapplication once or twice daily during peak season.
Longer-acting and oil-based formulas do hold better than light water-based sprays when horses stay reasonably dry, but even these lose effectiveness after heavy rain or a hard schooling session.
Treat any label claim as an upper limit in ideal conditions and adjust how often you top up to what you observe in practice.
Pairing spray with a fly rug and fly mask is the most reliable way to reduce overall fly burden without depending on topical repellents alone, particularly during peak midge hours at dawn and dusk.
Read our guide on how to kit out your horse for riding when the flies are at their worst for a full summer management plan.
Frequently asked questions
What is the best horse fly spray for UK horses?
There is no single answer because the right choice depends on your yard, your horse and your priorities. For heavy fly pressure or regular horsefly activity, a DEET or Icaridin-based spray gives the strongest and most durable protection.
For horses with sensitive skin or sweet itch, a plant-based, non-sting formula such as Barrier Enhanced is often a better fit.
For horses that hate being sprayed, a gel applied by hand gives you the same active ingredient with none of the noise or aerosol sensation. Start with the level of fly pressure your horse actually faces, then match the formulation to the horse.
What is the difference between DEET and DEET-free fly spray for horses?
DEET-based sprays use a synthetic repellent that gives strong, relatively long-lasting protection: the right choice when horseflies or midges are a serious problem and you need reliability through a full day.
DEET-free options include Icaridin-based sprays, which are comparable in performance and often better tolerated on sensitive skin, and plant-based products using actives such as citronella, PMD or garlic.
Natural options generally need more frequent reapplication in heavy conditions. The key is choosing the right strength for your situation rather than assuming one category is always better than the other.
How long does horse fly spray last?
Most everyday sprays give a few hours of reliable protection in normal UK summer conditions and benefit from reapplication once or twice daily at the height of fly season.
Longer-acting formulas with oil-based or pyrethroid carriers can extend this noticeably in dry conditions. Sweat, rain and hosing reduce effectiveness significantly, regardless of what the label claims.
Reapply after heavy work or any thorough wetting, and treat any "up to X hours" figure as a best-case rather than a guaranteed duration.
Is DEET safe for horses?
Yes, when you use a licensed equine fly spray and follow the label. Equine DEET sprays sold in the UK are formulated at concentrations assessed as safe for direct animal application under UK regulatory rules.
Avoid eyes, nostrils, lips and broken skin. Patch test on sensitive types before full use, and do not combine multiple strong insecticides at once. If your horse has a history of skin reactions, start with a lower-strength or DEET-free option and speak to your vet if you need to step up.
Can I use fly spray on a horse with sweet itch?
Yes, but choose the product carefully. Sweet itch is an allergic reaction to midge bites, so the management priority is reducing midge contact through rugs, turnout timing and field management, with repellents covering the exposed skin that rugs cannot reach.
On already rubbed or sore areas, avoid standard fly sprays and choose a product specifically designed to be non-sting and safe on broken skin, such as Barrier Enhanced Formula Fly Repellent. Standard sprays applied directly to sweet itch lesions can cause stinging and worsen the irritation.
Can I use fly spray on my horse's face?
Yes, but do not spray directly at the face. Spray the product onto a soft cloth or sponge first, then wipe around the jaw, cheeks and the outside of the ears, keeping well clear of eyes, nostrils and lips. A gel or roll-on gives you better control for tight spots around the ears and under the forelock.
A well-fitted fly mask with ear covers does most of the work around the eyes and is a more reliable solution for horses that are very reactive to insects near the face.
Is fly spray safe for pregnant mares and foals?
Labels vary, and many products are not specifically tested or approved for pregnant mares or very young foals. As a general rule, use the gentlest effective option, follow each label carefully, keep products away from the udder and teat area, and ask your vet before using stronger insecticide-based sprays on foals or mares close to foaling.
For young foals in particular, prioritise physical barriers such as lightweight fly rugs and stabling during peak midge times, and introduce any topical repellent gradually with a patch test first.
Should I rotate fly sprays to stop insects becoming resistant?
There is no strong evidence that rotating licensed fly sprays on a yard prevents insects developing resistance, in the way wormer rotation is used in parasite management. Focus instead on applying product correctly, covering the right areas and reapplying when conditions demand it.
If a product seems to be working less well, check your application first: missed areas, insufficient product and sweating are much more common reasons for underperformance than resistance. Switching can be worthwhile if your horse develops a skin reaction or if you need a different active against a specific insect challenge.
Browse the full range
Our full selection of horse fly repellents, sweet itch solutions and lice treatments is in our fly repellents, sweet itch and lice collection.
Related collections:
- Fly rugs for horses
- Fly masks for horses
- Sweet itch rugs
- Leovet horse care products
- Horse lotions and potions
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