Hairballs in Cats: Why They Happen and When to Worry

A hairball is not really a ball and it is not really a cough: it is swallowed grooming hair that failed to pass through the gut and came back up instead, usually as a damp, sausage-shaped plug of fur on the hall carpet at six in the morning. The occasional one in a well cat is part of living with a cat. The useful skill is knowing where the line sits between that and a cat whose hairballs have become a symptom.

Why cats get hairballs at all

A cat’s tongue is covered in backward-facing barbs, which is what makes grooming so efficient and also why almost every hair a cat loosens ends up swallowed rather than dropped on the floor. Most of that hair travels through the digestive tract and leaves in the litter tray without you ever knowing. Some of it does not, and hair that lingers in the stomach gathers into a mat that is easier to bring back up than to push on¹.

That makes hairballs a by-product of two normal things happening at once: a cat that grooms thoroughly, and a coat that sheds. Long-haired cats produce more of them for obvious reasons. So do cats in a heavy moult, and cats who groom a housemate as well as themselves.

What a hairball actually looks like

It comes up with obvious retching, and it produces something. The shape surprises first-time owners: hairballs are usually cylindrical rather than round, because they take the form of the oesophagus on the way up. There is often a little food or fluid with it. Once it is out, the cat typically shakes itself off, walks away, and asks for breakfast.

The important contrast is with a cat that heaves repeatedly and produces nothing at all. Cats with asthma or a chest problem cough with the neck extended and the shoulders low, an action owners very reasonably describe as trying to bring up a hairball². Nothing arrives because there was never a hairball. If your cat is doing this, our guide to vomiting in cats covers the difference in more detail, and it is a conversation to have with your vet rather than a pattern to watch for another fortnight.

How often is too often

There is no published number that separates fine from not fine, and any article that gives you one is inventing it. What vets tend to work with instead is the pattern for your particular cat. An occasional hairball from a long-haired cat in spring is different from a short-haired cat producing one every week.

Two changes are worth acting on:

• More than there used to be. A cat that has gone from rare to routine is usually either grooming more than it used to, or its gut is moving things through less efficiently. Both have causes worth finding.
• Hairballs plus anything else. Weight loss, a change in appetite, diarrhoea, low mood, or a coat that has gone dull all shift this from housekeeping to a symptom. Our list of the signs your cat is sick is a good cross-check.

Frequent vomiting in cats is often attributed to hairballs when the underlying issue is gastrointestinal, which is why an increase deserves a proper look rather than a remedy from the pet-shop shelf³.

The over-grooming question

When hairballs increase, the hair is usually the last step in the story, not the first. A cat that has started grooming excessively is doing it for a reason, and the common ones are itch, pain, and stress. Fleas are the classic itch, and a cat can carry them without you ever seeing one, which our guide to fleas, ticks and worms goes into. Food sensitivities and skin allergies do the same thing. So does anxiety: over-grooming is one of the recognised ways cats express it, sometimes to the point of a bald strip along the belly or the inside of a back leg⁴. If that sounds familiar, read our guide to cat anxiety and stress alongside this one.

The reverse is just as informative. An older cat whose hairballs stop, and whose coat starts looking unkempt or matted along the back and hips, has very often stopped grooming because twisting hurts. Arthritis is badly under-recognised in cats, partly because they express it by quietly doing less rather than by limping, and a neglected coat is one of the earlier hints. Our guide to arthritis in cats covers what else to look for.

What actually helps

Brushing is the whole game, and everything else is a supporting act. Hair on a comb is hair that never reaches the stomach, and for a long-haired cat that means most days, not most weeks. Short-haired cats manage well with a few sessions a week and more during a moult. Cats who dislike being brushed usually tolerate short, frequent sessions far better than long ones, and a rubber grooming mitt is often accepted by a cat who hates a comb.

The rest of the toolkit:

• Water. A well-hydrated gut moves things along more easily. Our notes on getting a cat to drink more water are worth a look if your cat is a reluctant drinker, and wet food contributes here too, as our comparison of wet versus dry food explains.
• A complete, life-stage-appropriate diet. Coat quality and gut function both depend on it; see our cat nutrition guide.
• Hairball-control foods and lubricant pastes. These help some cats. Ask your vet before adding them, particularly if your cat is on a prescribed diet, because a paste or a switch can quietly undo the point of that diet.

When to stop managing and start phoning

Some situations are not hairballs at all, and treating them as one costs time you may not have. Ring your vet the same day for repeated retching that brings nothing up over several hours, a cat that is off food and subdued alongside the retching, a tense or swollen belly, or no output in the litter tray. Rarely, a mass of hair causes a genuine blockage, and that is a surgical problem rather than a patient one¹. Our guide to when to take a cat to the vet sets out the wider list of things that cannot wait until morning.

A note from Hannah

I spent about a year congratulating myself on how well I was managing Marmalade’s hairballs. Paste, a hairball food, a comb by the sofa, and still one or two a week. What I had not registered was that he was also licking the same patch of his flank until it looked thin, which I had filed under “cats are odd”. The vet found flea dirt within about ninety seconds, despite a household I would have sworn was flea-free, and the hairballs went away when the itch did. I had been treating the hair, which was the only part of the problem I could see on the carpet.

This guide is general information, not advice about your individual cat. If your cat’s hairballs have become frequent, come with any other change, or involve retching that produces nothing, your own vet can examine them and work out which of these stories it is.