Written by Terry Smith

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UK’s best rat poison: professional rat and mouse poison compared for strength in the garden

This article was last updated on January 31st, 2023 at 7:20 am

The wheat at the back of our fields have just been cut and it’s no exaggeration to say I’ve seen a dozen mice wandering over the road to the nearest farm, and no doubt scoped out my house too just to add to the recent problem I’ve been having with rats around my chicken coops. I initially used humane mouse traps as well as some mouse repellents and even tried to setup some humane rat traps too which inspired me to write an article about getting rats and mice out of your garden. In the end, I got fed up with being overrun and found myself back at the most effective solution: a quality mouse and rat poison combo. The reason I mention rats as well, so any of these products are basically rodent solutions and so work for rats and mice equally well. So to help you guys out I decided to split test the two different types of best rat poison you’ll encounter: Brodifacoum vs bromadioloneThe results were very interesting indeed. While I have absolutely no reason to doubt the claims Brodifacoum based rat poison is 4-6 times stronger in terms of amount needed to be consumed, the Bromadiolone was far quicker acting on our mouse test which feels more humane to me. I will continue that testing and update you accordingly.

I tested Pest Expert Formula ‘B+’ on a rodent to really find out what these rat killers are doing

Now the manufacturers say Brodifacoum based rat poison is far more potent. Maybe it is, but that’s not what my testing proved when to me – I tested the Pest Expert Formula ‘B+’ vs the Roshield 600g Rat & Mouse Killer Poison Control Bait Blocks.

I personally tested the Roshield 600g Rat & Mouse Killer Poison Control Bait Blocks

I’m sorry for the video. But it is the reality of what we are doing when we use rat poison. If you don’t like it then I’d refer you back to some humane rat trap options.


PROTIP FROM TESTING: If you buy rat poison bait blocks absolutely make sure they are tied down so rodents have to consume them there and then rather than carry them away. They’ll often bury the blocks for later if they can carry them.

Make sure you understand the danger of rat poison

Now you need to realise poison is much better suited to ridding yourself of rodents outside. Indoors, you still need to stick with good old trapping. The reason is super simple. If a rat or mouse feels unwell, they will head back to their nest and most likely die there if you’ve fed them bait. That is not healthy for you or your family at all! Mouse traps or rat traps indoors, bait outside!

So with that said, I did wonder why the rat and mouse traps didn’t really make a difference outside. And it’s frustrating as hell if you have chickens and want to keep the chicken coops clear or rats! As I learned the hard way without researching first (luckily for you guys I know what does and doesn’t work), they can have 6-8 babies, every 8 weeks 😀 So, basically, you just can’t suppress them if the food is available and with that abundance of food over the road for a short while each year a population booms around my area. If you live in an urban, or built area if you prefer and the rats get at the bins then it’s going to be the same problem but much worse since food is available all year around!

So before I go into how to pick the best rat poison (or mouse poison) for you here’s my list to professionally rid myself of these rodents, but DIY style:

My top picks for the best rat and mouse poison options in the UK:

Roshield 600g Rat & Mouse Killer Poison Control Bait Blocks – Professional grade rat poison and must have for mice too. British manufactured.[personally tested and proven to kill rodents quickest – it took just two days for mice and rat test on it’s way]

Pest Expert Formula ‘B+’ Advanced Rat & Mouse Killer Poison 900g – [highest Brodifacoum content in the UK – heavy duty option personally tested] Best value for money too!

Ratkil Rat Poison (6 x25g) Rat Bait & Mouse Poison Grain – Strongest Maximum Strength Rodent Killer: Top alternative rat poison – neck and neck with Roshield

The Big Cheese STV213 All-Weather Block Bait – Great alternative rat and mouse poison if Roshield is unavailable

Opkill Rat Poison & Mouse killer – Strongest Available Weatherproof Bat for Professional and Domestic use

Contego Home Shield Rat and Mouse Killer Poison

How to pick the best rat poison for you and your family

So in this article I’ve picked the best rat poison based on price, strength, speed it fixes your rat or mouse problem, how safe it is to use, and ease of use. Much of which will be best for you boils down to personal circumstances. For example, block poison is very effective and also super easy application with minimal mess and fuss. Grain is pretty easy to use but requires a bait station. However, since the recent change in laws all poison used for rats and mice by non professional operators must be housed in a bait station so blocks may not be the advantage they once were over grain and pellet options since they also need a bait station to follow regulation. However, if you have kids, with a block being locked in a station you have far more confidence that the poison will not get out of the area you set.

Brodifacoum vs bromadiolone

So after a long email conversation with Pest Expert – I found out that Brodifacoum is 4-6 times stronger than bromadiolone. Now the interesting thing is I have no doubts about this claim, but in terms of efficiency and quick kill, I found the weaker bromadiolone to be three days faster acting! So from my perspective a humane way is quicker, so I’d actually naturally prefer the bromadiolone. I would recommend a look at the pest expert bromadiolone as there is no doubt this is a good honest guy, but I am glad I have helped bring transparency to the confusion surrounding these two different types of rat poison.


Block poison

Universally the most popular for a whole host of reasons and also my favourite method of using rat poison too. Most professionals advocate this method or one with a method of making a rat or mouse nibble at the food there and then inside a bait box under control, rather than a grain or pellet that will allow them to wander off with a chunk far more easily. The Roshield rat poison demonstrates this best on this review without question. Interestingly, the larger the bait, the more likely a rat is to wander off and cache it. The beauty of a bait box and blocks though is the ability to tie the blocks in, ensuring they have to eat little bits rather than drag it away. Here’s a picture of rat poison blocks with holes running through it:

rat poison blocks – holes running through

Grain poison

Grain poison works exactly the same way as block poison, it’s just broken into grains. Actually, I made a bit of a fuss about how blocks are easier. Some scientific studies show the larger the food, the more likely a rodent is to store it. A typical example of a quality grain poison is the Ratkill rat poison. It mimics the taste of grain and wheat with added flavour that makes it highly appealing to both rats and mice. They devour said poison and normally that will be enough. How long it takes grains to work largely depends on the size of the problem. Some not the bait is gone but they still have rats. My expectation in this case is the rat has stored the food, or there are more than anticipated. Continue with your dosing and try to eliminate any other food sources that may cause them to store this one.

Why use a bait box?

Well for a start it’s the law now. But aside from that if you have pets or children and a rat or mouse manages to pull bait to an area they’ll come into contact with, much worse younger children or pets that put anything in their mouths. Obviously this is a recipe for disaster and one of the very few sensible rules to come out of the EU. Why do I say that? You’re thinking we are sensible and know not to let this get in harms way and that’s fine. But what about what the rat does? Did you know they’ll store food in hidden places at any opportunity. It stands to reason they would want to keep their food safe for a rainy day so a bait box takes away a decent degree of chance and what would otherwise be left to luck.

Talking of rain, what you really don’t want is these rodenticides running into the water as it’s harmful to aquatic life too. A bait box keeps rat poison dry and better yet, if it is raining rats and mice will stick around and eat in there too!

With a fuller understanding of what rat poison is please find our picks for the best professional rat poison that you can use in your home:

Roshield was the professional pick a couple of years ago when I looked into this and still I rate it best rat poison in the UK after personally testing it extensively. These are British manufactured, made by Brits, and they’ve no been doing this professionally just shy of twenty years!

UPDATE AFTER TESTING: After I tested it side by side with Pest Expert Brodifacoum I have no doubt in my mind whatsoever that this deserves to remain top pick. Whilst the Brodifacoum products may offer better value in that they are 4-6 times stronger in the sense you need to consume less, my testing as you can see from the video showed me that either the rodent prefers the bait block, or it genuinely does kill much more quickly. As you’ll see from my quick video it takes a couple of days after consumption for rodents to perish. I will continue to trap and hopefully catch a rat as opposed to mouse so that we can be sure the comparison is fair. However, a rodent is a rodent. I would be highly surprised if my testing shows differently but with that said, I will still try to provide maximum transparency.

You also can buy 600g times two from Amazon at considerably reduced numbers so if you are overrun then this isn’t bad value at all. I would probably say though, Pest Expert pips this on value if you’re on a budget.  they come in 300g bags which is pretty convenient:

Roshield 600g Rat & Mouse Killer Poison Control comes in 300g bags

How you deal with Roshield is pretty simple. Buy it from the link provided. Put it in a bait box like the one below and secure the baits in so the rats or mice can’t pull the bait out of the box:

Bait box – place rat poison in the stations

Then wait for the magic, it’s not overnight, but over the course of about 6 weeks the population that always spikes where I live was gone. Why I really like denatonium benzoate above all other rat poisons I’ve used or am aware of, this one I know for sure has a chemical called denatonium benzoate. This is horribly nasty and bitter on the human palette so there’s no chance a mouse can scurry off with a nibble, drop it, and have it land with a small toddler in the garden whom unknowingly starts eating it. That should not happen, they should find it vulgar and spit it out, almost guaranteeing they can’t ingest large quantities. With that said, this absolutely does not mean use this with little kids running around the garden!!! Due diligence should be considered please. On the flip side, to a rat it tastes chocolatey and they can’t get enough! Ideal then!

Being a professional quality and super strength, you absolutely must put these in a bait station please, in fact, it is now the law even in your home when using rat poison. And whilst this product is approved for both indoor and outdoor use, I implore you to consider a rat or mouse trap indoors, be it a standard kill trap or humane one. Don’t risk the rodent passing away in a difficult to reach space like a stud wall with insulation in. I see many many people are using this indoors, ‘caveat emptor’ I say. This is a professional strength rat poison and much better suited to outdoors.

Some have had problem with rats taking the bait – so to speak 🙂 Well, give it time. If there’s a food source they know or prefer more they’ll finish first, a month or so and you’ll normally solve the problem, it’s very rare cases this won’t work that I’m aware of. Rats will also attempt to cache food sometimes so you need to be sure they’ve eaten the bait, and not just taken it to store away somewhere. Tying down the bait will help this.

The last thing before you go ahead and buy is watch this video please. It’s good for your safety, and with that in mind please be careful with these:


  • Gets rid of all the rats in 35 days – quick acting chemicals [I personally tested this by catching a mouse and it perished in just two days!!]
  • Uses chocolaty smell to attract the rat – they love the taste
  • Has to be used in a safe bait box – keep your family and pets safe
  • Have been formed well so that the blocks are compact
  • Roshield have holes in bait so you can tie or fix them into your bait box stopping rats drag them away.


  • Very strong so please keep away from family and pets – it has the same effect on pets and humans so please be careful.
  • Dangerous to humans and pets – use a bait box and be careful at all times
  • In my opinion not so suited to indoors but many many use it this way for serious infestations.

Currently testing the Pest Expert Formula I have established it has the highest concentrate of Brodifacoum in the UK. At 0.0029% it is 20% more than all competitors I’ve found in the UK so far. This is a far more potent active ingredient than Bromadiolone. I’m currently running a split test with this product and Roshield Brodifacoum based rat killer, it’s direct competitor and I will report back shortly on those tests.

UPDATE AFTER TESTING: Whilst this product works superbly as expected it is slower acting on rodents than the bromadiolone compound. However at price point on the basis 4-6 times less compound needs to be consumed, this vastly outweighs the bee

There are reports of this being effective within a few days up to weeks. You may need to give it a chance if they are not taking it straight away. Assuming there’s a familiar food source available it might be difficult to get them feeding on a new food so be persistent and do your best to reduce that and I expect you to get the results.

Please note being a grain it’s even more important than ever to be using a bait box. A sealed container that stops other pets and wildlife getting in. Also. being grain based you don’t want this getting wet either.

Overall given the sheer quantity of product they give for the money its super value. The next time I update this review I’d expect to see this being the best seller in the UK if they keep the same pricing to quantity model.


  • Excellent value for money – two times more than Ratkil for similar costs
  • Definitely works – the active ingredient Brodifacoum is working as rat poison for sure
  • Easy to follow instructions
  • Works in a few days up to weeks


  • Must use a bait box
  • Rats may take to the bait slowly – this is because of other readily available food sources

Handily they give you a video on how to use their own bait box too:

Ratkil Rat Poison comes as a grain and is one of the strongest poisons available without professional licenses and will solve mouse problems just as efficiently as rat. For that matter, it’s toxic to everything pretty much. So using a bait box is absolutely essential, in fact, it is not the law in the UK and EU.

The way it works is pretty simple. The grain is made from long grains and cereals to give the same taste of a rodents natural food source. In truth this is a very similar rat and mouse poison to Roshield in effectiveness when compared. The difference I can see is Brodifacoum which is a different active ingredient but equally effective at its job as a rat poison. In terms of how long this will take to suppress the problem, some note a few days while others weeks. Eventually you will solve the problem with this rat poison.

Many people are using this product indoors. I have to tell you while I know it’ll work, I have to say having a rat die in the loft or wall is not what you want. Wherever possible trap indoors and use this bait outside. When it comes to the garden this is super effective. Just place the sachet in the garden unopened. The rats and mice will do the rest. I note some open the sachets but this isn’t necessary and I think the idea behind not opening is the fact you don’t come into contact with said poison. And, be sure to hide the remainder away in a locked box, the rats and mice really will get a taste for this and go after the other sachets too 🙂

I noticed some suggested this isn’t working. I find that hard to believe. This is a nasty nasty compound that thins the blood and causes organs to simply fail. The likelier story is that the rats have stored the bait for later consumption. Sorry to get quite so graphic in description but it really is you vs rat.


  • Super effective professional and commercial grade – rats don’t really stand a chance
  • Very well priced with 6 sachets so you’ll have some left over for sure
  • Loads into bait boxes nicely and easily without touching the poison as you don’t need to open the sachet
  • Clear instructions – very easy to follow so you know how to eliminate an infestation
  • Quick to solve the rat problem


  • Very toxic – must be placed carefully with consideration to your pets and of course children
  • Must use a bait box – you don’t want this to be spread around by rats or mice.


4. The Big Cheese STV213 All-Weather Block Bait

The Big Cheese STV213 All-Weather Block Bait works in a pretty similar way to the Roshield. You can load and fix them into a bait box without the worry of a mouse or rat dragging one into the reach of your pets or children. Before we get going lets take a look at their demo video which helps you understand better how to keep your family and pets safe too:

Now as you can see they recommend their own bait box, that wasn’t the purpose of showing you the video, more the different types that are available; rat or mouse boxes. You can get the same type of locking box from anyone and they’ll be compatible with the Big Cheese STV213 All-Weather Block Bait.

The claim is they can be used inside and out. Whilst many do use them inside I always advocate this as a last resort or for a problem a typical rat or mouse trap won’t solve. Rats will feed on this both in dry and wet conditions so you’re sure to get your targets. The best thing about the wax blocks is of course that wax repels water so a great choice for damper conditions. A word of warning though, don’t let this get too wet as you don’t want the chemicals running into any water like a pond or stream nearby.

Some report these work in a matter of days but I would say from personal experience a spike in the local numbers can literally take weeks to get control of. Don’t give up and you’ll get there!

One super handy tip is to actually screw these down inside your bait box too, not just tie them. the rats and mice are then forced to nibble at them. One of the biggest problems is the rats taking these away and storing them. Sometimes they’ll never get eaten and leaves you frustrated because you feel it’s not working!

The other thing that can stop these working is a sheer abundance of food elsewhere. Ensure there’s no other easy options and this will then get eaten and do its job! I see a few suggesting these do not work. Following the above gives a much better chance!


  • Pretty good at repelling water – the waxy formula helps to keep them from getting wet.
  • Well priced – with the new formula being twice as effective they are now seriously good value
  • They sit nicely in bait boxes and firm enough to screw down too


  • Must keep them away from pets and children
  • If you don’t screw them down or fix firmly rats can have them away to storage and may never eat them.

I mean seriously? The title pretty much takes away a large chunk of my work here but to be fair they aren’t wrong.

The waterproof fast acting claims are true. Being a ax based product it means it naturally repels water, much in the same way as the Big Cheese STV213 bat blocks do. The rats really do go for it too. The combination of feeds means one is bound to tickle a rat or mouse’s fancy so you’ve a higher chance of getting them to eat it. This is one of the key reasons Roshield is the best pick incidentally.

And much like the Roshield, with a solid block and hole in the centre, you can tie or pin these down ensuring rats nibble away at them in the station rather than dragging them away for storage and consumption another day! And much like the Roshield, the chemical formula is similar, taking advantage of bromadiolone. So this is a good alternative choice if you don’t fancy Roshield or it’s out of stock.

As the title says this is ideal for domestic use too as well as professional. With that said, please take care if you do decide to use this indoors. A bait both with a firm fix on the bait is essential.

Some suggest it doesn’t work for them – my guess is it’s the old storing food problem, force them to eat it by removing all other food sources then we can workout if they are immune (unlikely).


  • Excellent quality – very similar to Roshield the top pick
  • Nicely waterproof because of the wax formula
  • Different feeds – helps ensure there’s something in there for every rat and mouse


  • Must use a bait box (like all baits now its the law)
  • Some claim it doesn’t work – following instructions works great most times though

The Contego Home Shield Rat and Mouse Killer Poison is the last on the list and well worth it’s inclusion. This is one of the Bromadiolone based rat poisons, similar to Opkil and Roshield. The first thing to remember is you’ll need a bait box just like all other picks on this list. This is a container that stops the rats running off with bait, dispersing it around your home. Whilst it appears an extra expense, I really do think it’s worth its weight in gold to keep your family safe and protected.

the hole in the bait is similar to almost all bait blocks and serves to allow you a way to fix your bait down. Just because you have a bat box doesn’t automatically stop rodents running off with bait. You definitely want to tie and pin down the bait which will force them to eat there and then. This is obviously the best way to rid yourself of a rat and mouse problem!

It’s designed for indoor and outdoor use. If you’ve read all through the article though you’ll know just how vehemently I deny the use indoors unless it’s absolutely necessary. You should always try with rat and mouse traps first indoors. Appreciated this sometimes is ineffective compared to poison that almost always gets the rat!


  • Excellent formula – just like Roshield
  • Definitely effective – mice and rats die within days up to weeks
  • Well priced – one packs enough for most homes.


  • Must use a bait box – its the law now.
  • Some have reported Ratkil to be more effective – it’s possible the rats and mice stored this rather than eaten it!

Why buy rat and mouse poison?

When I tried with mouse and rat traps, humane ones actually loaded with goodies it was a complete failure of a plan, here’s a look at that nice rat trap:

humane rat and mouse trap didn’t work at suppressing my rodent problem at all 🙁

Now I used this because I just thought it was nicer but releasing them a couple of fields down made absolutely no difference at all. What made the difference was Roshield rat poison.

Have you seen some pesky mice at your home? If yes, then it must be the right time to get something which will help you to battle these pests. They not only infest your home but they also destroy things by biting things and having babies at your home. Rats and mice are also known to carry different diseases. It is best to try to eradicate them as soon as you catch them in a space where you will never want them. Here we will provide some of the reviews of products which are great for getting rid of mice and rats. Do try to use them so that it doesn’t turn out to be a greater problem.

About Terry Smith

I’m Terry Smith from gardentoolbox.co.uk, a professional landscape designer, hobbyist gardener, and barbecue fanatic with 20 years experience building and restoring. So as you go through my site you'll watch me document some of the professional garden installs I make as well as the major projects I take on at home. While sharing those experiences and guiding you, I'll be recommending some great tools I use to enable this along the way so you can really buy in confidence. Always feel free to pop me a message: info@gardentoolbox.co.uk

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