About this guide
This guide covers rodenticides and poison for mouse control specifically — how anticoagulant products work for mice, how mouse feeding behaviour differs from rats and affects bait strategy, the CRRU regulations that apply to professional use, resistance issues in UK mouse populations, and safe use guidance. The page supports Apex Pest Control Ltd's mouse control service by explaining the professional approach to rodenticide selection before users choose a treatment provider.
Rodenticide bait is one of the primary tools for mouse control in the UK, but applying it effectively to a mouse infestation requires understanding how house mice feed and respond to bait — which differs significantly from brown rats. A programme designed for rats will underperform on a mouse infestation if these differences are not accounted for.
How house mice feed and why it matters for bait strategy
House mice (Mus musculus) consume only 3–5 grams of food per day but feed at 20–30 different points within their 3–8 metre home range each night. This nibbling pattern means that a mouse may consume a small quantity of bait at each visit, accumulating a lethal dose over multiple feeding events rather than in a single session.
This has important implications for bait strategy: bait stations must be stocked consistently throughout the treatment period so that each feeding visit contributes to the lethal dose. An empty station disrupts the accumulation. For this reason, bait take must be assessed and replenished at every monitoring visit — not just checked and recorded.
Mice are also neophilic — they explore new objects in their environment readily and will typically accept a new bait station within hours of placement. This is in sharp contrast to brown rats, which are neophobic and may take several days to approach a new station. Bait acceptance in mouse programmes is therefore generally faster than in rat programmes.
House mice consume only 3–5 grams of food per day across 20–30 feeding points, meaning that bait station stocking consistency throughout the treatment period is critical to ensure each visit contributes to a cumulative lethal anticoagulant dose.
— BPCA Pest Technician Reference Manual, 2023
Anticoagulant rodenticide options for mice
First-generation anticoagulants (FGARs): Warfarin and coumatetralyl require multiple feeds to accumulate a lethal dose — which suits the nibbling behaviour of mice if bait stations are consistently stocked. FGARs have lower secondary poisoning risk than SGARs. Consumer mouse rodenticide products are limited to FGAR formulations.
Second-generation anticoagulants (SGARs): Brodifacoum, bromadiolone, difethialone, and difenacoum are more potent and are effective against FGAR-resistant populations. Since January 2026, outdoor professional use of SGARs requires the technician to hold the RSPH Level 2 Award in Rodent Control and be CRRU-registered.
Bait formulation: Grain and seed formulations are often preferred for mice because they match the natural foraging preference of house mice. Wax blocks are also effective and more weather-resistant for outdoor station use. Paste formulations work well in areas with competing food sources where a highly palatable product is needed.
Do not use mothballs or naphthalene as a mouse poison or deterrent — they are not licensed under the Biocidal Products Regulation for rodent control and are not effective against mice in real building conditions. Bromethalin is not licensed for use in the UK or EU. Only use products from the approved UK rodenticide register.
Resistance in UK mouse populations
Warfarin resistance has been documented in house mouse populations in parts of the UK, though it is less extensively mapped than brown rat resistance. Where FGAR resistance is suspected — typically where a programme using warfarin-based consumer products has been ongoing without effect — professional assessment will identify the appropriate product choice. SGAR products are effective against warfarin-resistant mouse populations.
Bait station placement for mouse programmes
Mouse bait station placement differs from rat programmes due to the smaller home range. Stations should be deployed at multiple points within the active area — typically every 2–3 metres along active runs — rather than at wider spacing. Common placement locations include behind appliances, under kitchen unit kickplates, in the cupboard under the sink, in corners with confirmed droppings, and wherever gnaw marks or grease smear marks confirm regular mouse travel.
Because mice are neophilic, stations will be accepted quickly and bait take should be evident within 24–48 hours of placement. Very low bait take after 48 hours suggests the station is not on an active travel route and should be repositioned.
Combining rodenticide bait with proofing
Rodenticide bait reduces the existing mouse population but does not prevent re-infestation if entry points remain open. Mice can enter through gaps as small as 6 mm. A complete mouse control programme always includes identification and sealing of entry points alongside the bait programme. Without proofing, a successful knockdown will be followed by re-colonisation from neighbouring areas or from mice in wall voids that were not exposed to the bait.
Frequently Asked Questions
What rodenticide is best for mice?
The choice depends on resistance patterns and site constraints. Grain or seed formulations of anticoagulant rodenticides work well with mouse nibbling behaviour. Consumer products are limited to first-generation anticoagulants (FGARs) like warfarin. Where FGAR resistance is suspected, professional SGARs — brodifacoum, bromadiolone — are more effective. A professional pest controller selects based on site assessment and known local resistance.
How long does mouse poison take to work?
Anticoagulant rodenticides take 4–7 days to cause mortality after a lethal dose has been consumed across multiple feeding visits. Because mice feed in small quantities at many points, the cumulative lethal dose may take several days to accumulate even with daily bait access. Bait stations must remain stocked throughout this period.
Why are mice still eating bait but not dying?
Possible causes include warfarin resistance (particularly if a consumer FGAR product has been in use for some time); insufficient bait quantity at each station (mice are consuming small amounts below the lethal accumulation rate); competing food sources reducing the proportion of the mouse's diet made up of bait; or the wrong product for the local mouse population. A professional assessment will identify the cause.
Can I use rat poison for mice?
The same anticoagulant compounds are used for both species, but the bait formulation and station design should match the target species. Mouse-specific formulations (grain and seed) and smaller bait stations placed at shorter intervals suit the small home range and nibbling behaviour of house mice. Using a large rat bait station in a location scaled for rats may result in poor uptake in a mouse infestation.
Are mouse poison products safe to use around children and pets?
All rodenticides are toxic to mammals including humans, dogs, and cats. Bait must always be placed inside tamper-resistant, lockable stations — never loose on surfaces. Children and pets should not have access to areas where stations are deployed. If accidental ingestion is suspected, contact the National Poisons Information Service (NPIS) on 0344 892 0111 or a veterinarian immediately.
What is the CRRU code for mouse rodenticide use?
CRRU (Campaign for Responsible Rodenticide Use) governs professional anticoagulant use for all rodents including mice. From January 2026, outdoor use of second-generation anticoagulant rodenticides (SGARs) by professional pest controllers requires CRRU registration and the RSPH Level 2 Award in Rodent Control. The CRRU Code sets requirements for pre-treatment surveys, record-keeping, and product selection justification.
Why won't mice take rodenticide bait?
Mice are neophilic and typically accept new bait stations within hours. Very low bait take after 48 hours usually means the station is not on an active travel route and should be repositioned to a location with confirmed activity (droppings, gnaw marks). Over-competition from other food sources in the environment can also reduce bait take — food source management (securing waste and stored food) alongside treatment improves outcomes.