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How long does it take rat poison to work?

Possibly one of the most common questions we get asked. Well, there are several factors, which may increase or decrease effectiveness. For example, well placed rat poison in a heavily infested area can lead to effective results quickly. Whereas, poison which is placed without thought or not placed correctly will lead to negative results when controlling rats. At DIY Pest Control, we stock a wide range of rat poisons in different forms along with expert advice to deliver professional rat control results.

Types of rat poison

Rat poison comes in various formulations and it is becoming harder for the public to purchase in any other than small pre-packed ready to use sachets. Rats prefer bait that is highly palatable. The sweeter the bait the longer the rats will feed. The three key active ingredients used in rat poison are either difenacoum, bromadioline or brodifacoum. These poisons affect the rats’ blood clotting response, resulting in the rodents dying a few days later. The range of rat poisons we offer are;

  • Rat killer bait
  • Grain bait
  • Bait blocks

We strongly recommend placing rat poison in rat bait boxes for extra safety around the home. Our range of poisons can be purchased in different sizes depending on the size of the infestation you need to control. Alternatively, we sell rat control kits which contain everything you need in one handy pack. 

How to increase the effectiveness of rat poison

Now you know the different types of rat poison available, our experts have shared their ideas on how to make your rodenticide poison work quicker and deliver better results. Firstly, once the bait is laid the rat poison should be inspected frequently. Areas where bait has been eaten should be replenished as soon as possible. We recommend inspecting your bait no later than 3 days after it was laid and at least every seven days thereafter. Make sure to continue baiting until all feeding activity has stopped. Check out our top tips below for expert advice on the use of rat bait stations.

Rat bait stations

Bait stations are an effective way to secure bait safely. They also help to protect children and pets from coming into contact with the poison as well as protecting the poison from bad weather conditions.

  • Place rat bait stations roughly 30 feet apart and for heavier infestations 15 feet apart. Try and place the bait in the most affected areas.
  • Avoid moving the stations once placed as rats respond positively to familiarity.
  • Rats eat more bait than mice so replenishment is particularly important.
  • In wet conditions consider using all weather or weather resistant blocks.
  • To encourage the rodents into the bait boxes, use natural and familiar materials inside and around them

How long does it take for rat poison to work?

Once the rat consumes the poison it can take 2–3 days for the rodent to die. Incidentally, once a rat is poisoned it will stop feeding and this greatly reduces the risk of secondary poisoning. However, as mentioned above the effectiveness of the poison depends on several factors:

  1. Placing the poison correctly
  2. Replacing spoiled poison straight away
  3. Removing ALL other food sources
  4. Maintaining familiarity
  5. The size of the rat

If you need advice feel free to get in touch with a member of our team who will be happy to assist you with your rat infestation.

Recommended Products

Rentokil Rat Weatherproof Blocks 200g

These ready to use bait blocks are perfect for amateur use and this handy pack contains 10 bait blocks, for indoor and outdoor use. These are perfect to be used within a bait station.

1 pack price = £7.50 each

3 pack price = £6.52 each

Rodex Whole Wheat Sachets x5

This poison comes in 150g sachets. They are perfect for throwing into inaccessible places where they will stay dry until a rodent comes along and chews into the bag. They should only be used in lockable bait boxes and inaccessible areas to prevent access by non-target species.

1 pack price = £11.04 5 sachets (£2.21 each)

3 pack price = £31.20 15 sachets (£2.08 each)

Rentokil Rodine Rat Killer Grain Bait

This ready to use poison is perfect for amateur use and the handy pack contains 6 x 25g sachets for indoor and outdoor use. We also recommend placing this poison within a bait station. This poison can kill up to 12 rats.

1 pack price = £5.70 each

3 pack price = £4.98 each

Protecta Sidekick Rat Bait Box

This bait box is an economical way to upgrade from using non-tamper resistant bait stations to the security of tamper-resistance. It locks when closed and unlocks with Bell’s two-pronged Protecta key. This bait box is perfect for all weather conditions, its interior corners are rounded for easy cleaning and it opens easily for quick bait placement.

1 bait box = £7.14 each

3 bait boxes = £6.50 each


It is difficult to say exactly how long it can take rat poison to work, as there are many variables. The key is to be persistent and be vigilant. Placing the bait on the right rat run is vital. If the bait is not being taken, you might need to move it. Make sure there is always bait down and it is always palatable. We provide you with the most effective poisons on the market to help you control rats.

If you need any assistance or have any questions feel free to contact us today or get in touch with one of our experts on 01332 340898. 

Read more: How to control rats


  1. Hi, can you please help?

    On 1st June started to hear scratching noises & bits dropping in my loft above my daughters bedroom. This sounded quite wild like something chewing biting into something may be wood i dont know. I called pest control & they found no droppings or anything to see if its a squirrel rat or mice. The guy left some poison in the loft by the insulation area where the noise was coming from. Since then this noise like biting scratching is still there hasnt got any less. Yesterday the noise moved into the kitchen ceiling & today its back up in the loft. I dont think the poison has done anything or its not in the right place. I will call the guy again on monday. What else can i do in the meantime? Please help. Thank you

    1. Hi there. Poison takes a little while to work. It doesn’t kill instantly, so you may just need to give it a little more time. If there is no change after 7-10 days, you may need to add more poison or change its location.

  2. Trevor James

    I have 2 spare bedrooms that both have small roof rats in them, they were up above the ceiling tiles. Where I live used to be offices but turned into a large 7 room apartment the drop ceiling stayed unfortunately. Anyways there’s no windows or places to exit in these 2 rooms and I sealed the door gaps from the outside with vinyl planks,tin foil and duct tape lol. I only hear them a few times a night scratching and I managed to get a snap trap and poison inside I’m on day 4 I’m going to be patient but there has to be a better faster way nowadays in 2020. If I go in the room to attempt to catch it with a net you will not even see it as only a 10 foot by 10 foot room but it’s in there because I hear it later on. Is there not some kind of dynamite stick that doesn’t explode but smokes out or kills it instantly or some kind of gas I can flood in the room , lethal spray ect ? Thank you for your time!

    1. Hello Trevor. Unfortunately, despite being in 2020, traps and poison are still the go-to ways to kill rats. That said, traps are rarely effective against rats because they are not inquisitive enough to want to investigate them. If there is just the one rat in the room you might be lucky though. It is not unusual for poison to take 1-2 weeks to kill the rat. The toxicity needs to build up enough to be fatal, meaning how long the process takes varies, depending on the size of the rat and how much of the poison, if any, makes up its diet. Just check that the poison you are laying is being taken. If so, your rat will soon be gone

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