Description
Our verdict: One of the strongest rat and mouse poisons you can buy without a professional licence in the UK. It’s a single-feed brodifacoum grain bait, so a rodent can take a lethal dose in one visit. That’s useful against rats that are wary of traps or have stopped responding to weaker baits. Because it’s so strong, it also carries the most risk to pets and wildlife. Use it only in locked bait stations, and only for as long as the problem lasts.
Best for: established rat or mouse activity in and around buildings | Pack: 15 × 60g sachets | Active: brodifacoum 0.0029%
What is Pest Expert Formula B+?
Formula B+ is Pest Expert’s stronger version of its Formula B rodenticide. It’s a wax-free wholewheat grain bait containing brodifacoum at 0.0029%, which Pest Expert describes as the maximum legal strength for this type of product in the UK. The manufacturer claims it’s around 4× stronger than bromadiolone baits and 6× stronger than difenacoum baits, two common actives in supermarket rat poisons.
Brodifacoum is an anticoagulant: it stops the blood clotting. It isn’t instant. Rodents usually die a few days after feeding. That delay is deliberate, because it stops the rest of the colony linking the bait to the deaths and avoiding it. The bait comes in pre-measured 60g sachets, which you place unopened. Rodents chew straight through them, and you keep the grain off your hands.
Searching for “Formula B rat poison”? Formula B and Formula B+ use the same grain bait and the same active ingredient. B+ is the higher-strength version.
How to use it safely and effectively
- Confirm what you’re dealing with. Look for droppings, gnaw marks, greasy rub marks along walls and runs. Rat droppings are around 1–2cm long; mouse droppings are rice-sized. Not sure? See what to do when you find droppings.
- Use a lockable, tamper-resistant bait station. Put the sachets inside a station, not loose on the floor, especially if you have children, pets or wildlife nearby. Follow the label for exactly where the product may be used.
- Place stations along runs. Rodents move along walls and edges, so put stations against walls near droppings, behind appliances, in lofts and along fences next to buildings. Put mouse stations closer together than rat stations, because mice travel shorter distances.
- Check and top up every few days. Replace any sachets that have been eaten. If no bait has been taken for several days, move the station to a busier spot.
- Clear up when feeding stops. Wear gloves, look for dead rodents regularly, and dispose of them as the label directs. Take out any uneaten bait at the end of the treatment. Don’t leave poison down permanently “just in case”.
Pros and cons
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Who should pick something else?
- Have pets or children, or want to avoid poison? A trap box such as the Pest X Pro Shadow Rat Trap Box or NOPE! Rat Snap Traps kills without any risk of secondary poisoning, and you can see the result.
- Only dealing with mice indoors? Snap traps like the Uflix Quick-Snap Mouse Traps are often quicker. Compare options in the traps that actually get rid of mice.
- Rats in the loft, or a problem that’s come back more than once? Read what dealing with rats in the loft actually costs before deciding between DIY and a professional.
Frequently asked questions
How long does Formula B+ take to work?
As an anticoagulant, it usually takes a few days after a rodent feeds. You should see bait being taken within the first few days and activity dropping off over the following one to two weeks. Keep the stations topped up until rodents stop taking bait.
What’s the difference between Formula B and Formula B+?
Both are Pest Expert brodifacoum grain baits. B+ is the higher-strength version, at 0.0029% brodifacoum, which Pest Expert says is the strongest brodifacoum concentration available in the UK.
Is it safe to use if I have a dog or cat?
It’s dangerous if pets eat the bait or a poisoned rodent. Only use it in a lockable, tamper-resistant bait station that pets can’t open, and collect dead rodents promptly. If you think your pet has eaten any, contact your vet straight away and take the packaging with you.
Can I use it outdoors?
Follow the label: it states where the product may be used. In general, place consumer rodenticides in and around buildings, inside secure bait stations, and never scatter them loose in gardens or open areas.
Is this the best rat poison in the UK?
It’s among the strongest available to the public, which makes it a strong option when weaker baits have failed. “Best” depends on your situation, though. For many homes with pets, a well-placed trap is the safer, faster answer. See our guide to rat traps for alternatives.
Related guides
- The rat traps worth buying
- Rats in the loft: what it actually costs
- Traps everywhere and still getting mice?
Manufacturer details and safety information
- Brand: Pest Expert
- Active ingredient: Brodifacoum 0.0029%
- Form: Wax-free wholewheat grain in 15 × 60g sachets
- Target: Rats and mice
- Prolonged or repeated exposure may cause damage to organs. Handle with care and use only as directed.
- Use biocides safely. Always read the label and product information before use.
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