Best Mouse Poison UK 2026: What You Can Legally Buy

Mouse poison is one decision, not two. Almost everything that determines whether it works is settled by which active substance is in the pack — and on three of the five products below, the Amazon listing does not tell you what that substance is.

When Poison Is the Right Answer

Bait is not the default and the regulator does not treat it as one. HSE states that “Risk assessments carried out by regulators, including HSE, have shown that anticoagulants present a higher risk to people and non-target animals than is normally acceptable for authorisation in Great Britain and Northern Ireland.” They are authorised anyway, under controls, because the alternative is worse — but HSE’s own advice before you buy is that “it is important to remember to consider other available control methods, such as those listed above, before reaching for anticoagulant products.” (HSE).

In practice poison earns its place when mice are nesting somewhere you cannot reach — a wall cavity, under floorboards, behind a fitted kitchen — so that traps cannot be put where the animals actually are. If you can reach the runs, traps are the lower-risk tool and there is a separate page for them.

What You May Buy, and What the Label Requires

Rodenticides sold to the public are authorised on different terms from those sold to professionals. HSE says products for the general public may be restricted in the amount of active substance they contain, in where they can be used — for example only within a bait box — and in the maximum pack size that can be sold (HSE). That is why an amateur pack can carry less active substance than a professional one, and it is the honest answer to what “strongest” can mean on a shelf a householder can reach.

The bait station requirement is not guidance. CRRU UK, which co-ordinates UK rodenticide stewardship, reported that “Changes required by Health and Safety Executive to legally binding instructions on rodenticide product labels have significant implications for users in pest control, farming and gamekeeping.” Those instructions require a tamper-resistant station to be “Strong enough to prevent entry or destruction by dogs.” and “Lockable or sealable so that children and dogs cannot gain access through the opening or mechanisms used to fill the bait compartments.” (CRRU UK). One of the five products here says so itself: the Big Cheese blocks listing states that a tamper-resistant bait station is required by law.

And the box is your responsibility, not the bait manufacturer’s. CRRU is explicit that “It is the responsibility of the end user to ensure the bait station employed complies with the new label requirements.” Read the label on the pack you actually buy, and use it only as that label says.

Where Mouse Poison Does Not Work

This is the part most mouse poison pages leave out, and it is the reason baiting fails. House mice in the UK are widely resistant to anticoagulants. The Rodenticide Resistance Action Group puts it plainly: “Resistance is now so widespread it is often said that it is harder to find susceptible house mice than resistant ones.” (RRAG House Mouse Resistance Guideline).

That has a direct consequence for which substance to buy. Defra’s code of practice for rodent control states that “Resistance to the first-generation anticoagulants, and to the second-generation substances bromadiolone and difenacoum, is now so widespread in-house mice that, among the anticoagulant substances, only brodifacoum, difethialone and flocoumafen should be used against them.” (Defra code of practice). That code is written for poultry units and we have not altered its wording, including its own typo at “in-house mice”; the animal it describes is the same one in a kitchen.

RRAG reaches the same conclusion independently, in its own words rather than by repeating Defra’s. On difenacoum it advises that “It would therefore be prudent, in areas where resistance in house mice is suspected, not to use products that contain difenacoum.” On bromadiolone it goes further, saying its use against house mice in the UK is not recommended because it may not achieve adequate control and will make resistance worse. And on what to use instead: “products containing brodifacoum and flocoumafen should be the rodenticides of choice when carrying out control treatments against house mice in the UK.” (RRAG).

Read against the five products below, that is uncomfortable and we are not going to soften it. Two state brodifacoum. One states bromadiolone, the substance RRAG advises against for this species. Two state nothing at all, so you cannot tell from the listing whether you are buying a substance the guidance names or one it warns off.

What Decides the Choice

1. The active substance, before anything else

Pack size, block or grain, indoor or outdoor: none of it matters if the substance is one that resistant mice survive. Both sources above name brodifacoum among the substances to use against house mice, and both name bromadiolone and difenacoum among those to avoid. That single fact outranks every other column in the table at the bottom of this page.

2. Whether the listing states the substance at all

Three of the five products here are blocks, and only one of those three names its active substance on the Amazon listing. For the other two, neither the title, nor any feature bullet, nor the detail table gives it. A pack whose substance you cannot establish before buying is a pack you cannot check against the guidance above — the substance will be on the physical label, but by then you have bought it.

3. What “strongest” is actually available to you

RRAG uses the term low-strength bait for one “containing less than 30 ppm of the anticoagulant active substances”, notes that such baits “are available both to the general public and to professional pest control practitioners”, and advises that, where the labelling classification is not a factor, “formulations containing the highest available concentration of an active substance should always be used” (RRAG). The highest concentration any listing here states is 0.0029% brodifacoum, which is 29 parts per million — inside RRAG’s low-strength band. That is not a criticism of the product; it is what the amateur market is, and it is the honest reading of the word in this page’s title.

Best Overall — Pest Expert Formula B+ Rat & Mouse Killer Poison 900g

The listing states brodifacoum at 0.0029%, which is the substance both RRAG and Defra name for house mice, and it states that the bait kills in a single feed. Defra supports that property for this group of substances, with a condition worth keeping: “The increased toxicity of difethialone, brodifacoum and flocoumafen means that they can kill both rats and mice following only one feed on the bait, if enough bait is consumed.” (Defra code of practice). Single-feed does not mean one visit is enough if the mouse only nibbles. Fifteen 60g sachets is a lot of bait points for one house, which is the argument for the smaller pack below rather than against this one. The manufacturer’s own comparative strength claims are not repeated here.

Best Starter Pack — Pest Expert Formula B+ Mouse & Rat Poison 360g

The same stated formulation — brodifacoum 0.0029% — in six 60g sachets instead of fifteen, and the listing describes the pack in terms of the six bait points it covers. For one house, six baited points placed where you have actually seen activity is a realistic treatment rather than a reduced one. If the substance is the thing that matters, this pack and the one above are identical on it.

Best Blocks — The Big Cheese All-Weather Bait Block 15x10g

Fifteen ready-to-use 10g blocks, listed as moisture-resistant for indoor and outdoor use, and the listing is unusually specific about placement: two to three blocks every two to five metres for mice. It is also the one listing here that states the bait station requirement is a legal one. What it does not state, anywhere, is the active substance. This page previously told you it was difenacoum. That was not on the listing and we should not have said it — and if it is difenacoum, it is one of the two substances the guidance above advises against for house mice. Read the pack before you use it.

Best Bulk — The Big Cheese All-Weather Rodent Block 30x10g

Thirty 10g wax blocks, blue, listed as carrying a bitter taste to deter accidental ingestion. The same gap applies: no active substance is stated on the listing. One inconsistency is worth flagging because it is on the listing itself — the title, the detail table and the pack description all say thirty blocks, while one feature bullet says the pack contains fifteen. We have taken the figure the detail table gives.

Best Professional — Roshield Wax Block Bait 600g

This is the only one of the five whose listing gives a product authorisation number — UK-2016-0986-0007 — alongside its active substance, bromadiolone 0.0025%, and it names denatonium benzoate as the bitter agent. It is also the product whose stated substance the guidance above specifically advises against for house mice — RRAG says bromadiolone may not achieve adequate control of them and will worsen resistance. Against rats that reasoning does not apply in the same way, and the listing gives both as target species. For mice specifically, the two brodifacoum packs are what the sources point to.

If Poison Is Not the Answer

Proof the building. Bait removes the mice that are here; it does nothing about the gap they came through. Defra’s code is blunt about that order of work: its overall aim is to stop infestations becoming established in the first place, and it calls it unacceptable to keep making remedial applications of rodenticide on premises where too little attention is paid to keeping rodents out. It also records that proofing against mouse entry is often extremely difficult, because of how small a gap a mouse can pass through (Defra code of practice).

Traps, where you can reach the runs. If there are children, pets or non-target animals in the house and you would rather not have an anticoagulant in it at all, a trap is a different trade-off — see our mouse traps page.

A professional, if baiting has already failed once. Given how widespread resistance is, a treatment that has not worked is more likely to be a substance problem than a technique problem, and the substances that answer it are not sold to the public.

Placing and Checking Bait

1. Use enough bait points, and put them on the runs. Defra: “Mice live in small social groups and their erratic feeding behaviour results in them visiting several different food sources during periods of activity. Consequently, it is necessary to provide an adequate number of bait points in places where rodents are living or moving.” One station in one corner is not a treatment.
2. Every point goes in a locked station. This is the label condition, not a preference.
3. Do not let a point run empty. Defra: “If bait is allowed to run out (except in pulsed baiting), become unpalatable, or there are insufficient bait points, then control is likely to be unsuccessful.”
4. Move points that stop being touched. Defra: “For mice, regularly moving the location of bait points may help to maintain rodent interest.”
5. Judge it on bait taken, not on time passed. You cannot tell whether anything is feeding without opening the station, so keep the key and check it.
6. If consumption continues with no reduction in activity, stop and reconsider the substance. That is what resistance looks like from the outside, and adding more of the same bait does not answer it.

Best Mouse Poison Compared

Every column below is what the Amazon listing itself states. Where a listing does not state something, the cell says so rather than guessing — and on this page the “not stated” cells in the active substance column are the most important thing in the table.