Quick answer: Introduce cats slowly in stages: keep the new cat in a separate room, swap scents, feed both cats on either side of a closed door, let them see each other through a gate, then build up short supervised visits. Only move to the next stage when both cats are calm for a few days. It can take weeks or months.
This guide is general information, not veterinary advice. Your vet's instructions for your pet always come first.
The 7 stages
- Sanctuary room. The new cat gets its own room with litter, food, water, a scratcher and a hiding spot. Move on when it is eating, using the litter box and exploring.
- Scent swapping. Swap bedding, or rub a sock on each cat's cheeks and leave it with the other. Move on when both sniff calmly.
- Meals by the door. Feed both cats on either side of the closed door, moving the bowls closer over days.
- Seeing each other. Use a baby gate, screen door or a door open a crack, with food or play. Move on when both stay relaxed.
- Short supervised visits. Start with a few minutes, with toys and treats to keep things positive; end before anyone gets tense.
- Longer time together. Build up gradually; watch for stalking or blocking access to food and litter.
- Unsupervised. Only after days of calm, shared space.
Normal vs. too much
Normal early on: some hissing at the door, staring through a gap, a briefly puffed tail.
Too much, go back a stage: not eating, hiding all day, peeing outside the box, over-grooming, constant growling, chasing or fighting.
Set the house up first
- One litter box per cat, plus one extra.
- Separate food and water stations, spread out.
- Shelves or cat trees so cats can avoid each other.
- Hiding spots in every main room.
When it goes wrong
Setbacks are common. Separate the cats calmly, go back one stage for a few days, and keep sessions shorter. If fighting continues after weeks of careful work, talk to your vet; pain or illness can be behind aggression, and a vet behaviorist can help.
Frequently asked questions
How long does it take to introduce two cats?
Anywhere from a couple of weeks to a few months. The pace is set by the more nervous cat, and going back a stage after a bad day is normal.
Is hissing normal when introducing cats?
Some hissing or growling through a door early on is normal. Constant growling, chasing, not eating or peeing outside the litter box mean you should slow down and go back a stage.
Should I let my cats fight it out?
No. Putting cats together and letting them sort it out often causes lasting fear and aggression. Separate them safely with a board or towel, never your hands, and slow the introduction down.
When can I leave the cats alone together?
Only after several days of calm supervised time with no chasing, stalking or hiding, and both cats eating and using the litter box normally.
Keep it all on paper
Our printable planner turns these stages into a roadmap with "move on when" signs, a daily session log for both cats, a scent-swap and feeding-distance tracker, and a setback plan.
See the Cat-to-Cat Introduction Planner →