Mice keep coming back. What actually works without poison?

Mice keep coming back for one reason: the way in is still open, and there is still something to eat on the other side. Poison, traps and sprays deal with the mice you have today. Closing the gaps deals with the next ones. That is why years of effort can feel wasted, and why the fix is more about a torch and a tube of sealant than anything you put down.

Mice come in for warmth, shelter and food, and older houses, terraces and homes near fields or woods give them plenty of ways in.

Why they keep coming back

• A gap nobody has found yet. Mice fit through gaps far smaller than most people expect. Sealing nine holes and missing the tenth still leaves a door open.
• They live next door too. In terraced and semi-detached houses, lofts, wall cavities, under-floor spaces and pipe runs can connect homes. Your mice may be your neighbour’s mice.
• Food is still within reach. Pet food left down overnight, bird seed, crumbs behind the cooker, a bin without a lid.
• Treatment without proofing. Anything that only removes the mice inside leaves room for new ones to move in.

The plan, in order

1. Find the ways in. With a torch, look low and slowly: where pipes and cables pass through walls, behind the cooker and fridge, under the sink, behind the bath panel, under doors, around the boiler and the loft hatch. Fresh droppings and greasy smudges along a wall point to the route.
2. Seal them with things mice cannot chew. Pack steel wool into the gap, then cover it with sealant or filler. Expanding foam on its own gets chewed. Fit a door sweep to outside doors. Never block air bricks or vents: cover them with fine metal mesh instead. Our guide to sealing gaps goes through each spot.
3. Talk to the neighbours. If you share a wall or a loft space, ask whether they see mice too. Sealing both sides of a shared route works far better than one house alone.
4. Put food away. Hard containers with lids, bins with lids, pet bowls up at night, bird seed stored sealed.
5. Catch the ones inside, alive. Set live catch traps along walls where you found droppings, with a small dab of peanut butter. Check them every morning, because a mouse left in a trap too long suffers. Release as local law allows: ask your council or wildlife body where that is.
6. Clean up, then watch. Clear old droppings so any new ones stand out. Check the same spots once a week.

Kids, pets and droppings: put traps where children and pets cannot open them. Wear gloves for droppings and nests. Spray them with disinfectant, let it soak, then wipe up with paper towels. Do not sweep or vacuum them dry, as that lifts dust. The mice and rats guide has the full steps.

What people try that does not do the job

Poison as the first step. It feels decisive, and it is often what gets put down first. But it does not close a single gap, so new mice keep arriving. Poisoned mice can die under floors or in walls, where the smell lasts, and pets can be harmed by the bait or by eating a poisoned mouse. More on that in rat poison with pets in the house.

Peppermint oil and dryer sheets. Lots of people try them, and the reports are anecdotal at best. Mice that have food and shelter do not leave because of a smell. Ultrasonic plugs are the same story: see do ultrasonic repellers work.

When to get help

If you still find fresh droppings four weeks after sealing everything you can reach, a gap is still open somewhere, often in the loft, under the floor or behind fitted units. That is the time for a professional who does proofing, not just treatment. Ask them which gaps they will seal, what with, whether they avoid poison and glue boards, and whether a return visit is included.

If you rent, tell your landlord or agent in writing, with dated photos of droppings and the gaps you found. Proofing the building is usually their side. Our answers on documenting pests and a landlord who won’t act cover what to send. In the UK, council environmental health can advise; elsewhere, try the local housing authority or a tenants’ union.

A dead mouse you cannot reach, under a bath or a floor, will smell for a while and then fade. If the smell is strong or flies appear, ask your landlord or a pro to open the panel.