A hairball is a clump of swallowed fur that accumulates in a cat’s stomach and is eventually vomited back up. The medical term is trichobezoar. Most cats produce one every week or two, and while that’s usually harmless, hairballs can occasionally cause serious digestive blockages that require veterinary care.
How Cats End Up Swallowing Their Own Fur
A cat’s tongue is covered in hundreds of sharp, backward-facing spines made of keratin, the same material as human fingernails. These spines, called papillae, are scoop-shaped with tiny hollow cavities at the tip. During grooming, saliva wicks into these cavities and gets released onto the fur, while the spines physically comb through the coat to remove loose hairs, dirt, and fleas.
Grooming follows a consistent four-phase cycle: the tongue extends, stiffens and expands laterally, sweeps through the fur, then retracts in a U-shaped curl. As the tongue pulls back, those rear-facing spines drag loose hair toward the throat. Cats can’t spit this hair out, so they swallow it. Most of the time, swallowed fur passes through the stomach and intestines without any trouble and leaves the body in feces. But when hair accumulates in the stomach faster than it can move along, it mats together into a hairball.
What a Hairball Looks Like
Despite the name, hairballs are rarely ball-shaped. They’re typically elongated and log-shaped because they get compressed as they travel back up through the narrow esophagus. They often come up coated in mucus or mixed with a small amount of food. The color usually matches your cat’s fur, though the mucus coating can give it a darker, slightly greenish tinge.
Which Cats Get Them Most
Long-haired cats are roughly twice as likely as short-haired cats to produce hairballs frequently. In a study of cats that developed intestinal blockages from hair, 84% were long- or medium-haired breeds. Domestic longhairs made up nearly half the cases, followed by Maine Coons at about 20% and domestic shorthairs at 16%. Persians, Himalayans, Birmans, Ragdolls, and Norwegian Forest Cats also appeared in the data. The logic is straightforward: longer fur is harder to pass through the stomach’s exit and the intestines, so it’s more likely to accumulate.
Coat length isn’t the only factor. Any condition that causes a cat to groom excessively increases how much hair it swallows. Flea allergy dermatitis, other skin allergies, and stress-related overgrooming all raise hairball risk. If a short-haired cat is producing frequent hairballs, that can actually be a red flag for underlying gastrointestinal disease or a skin condition driving excessive grooming, since short fur normally passes through the digestive tract without trouble.
How to Tell a Hairball From Regular Vomiting
The sound is unmistakable once you’ve heard it. A cat working up a hairball will hack, gag, and retch in a distinctive rhythmic pattern, often hunched low with its neck extended. This can last anywhere from a few seconds to a couple of minutes before the hairball finally comes up. It looks and sounds alarming, but it’s a normal expulsion process.
Regular vomiting tends to involve more abdominal heaving and often produces partially digested food or bile without a visible clump of hair. If your cat is repeatedly retching without producing anything, that’s a different situation entirely and warrants attention.
When a Hairball Becomes Dangerous
Most hairballs are a minor nuisance. The concern is when a mass of hair doesn’t come back up and doesn’t pass through the intestines. Instead, it lodges somewhere in the digestive tract and creates a blockage. In documented cases, these obstructions have occurred in the small intestine (the jejunum and ileum) and at the junction between the small and large intestine.
Watch for these signs that suggest something more serious than a routine hairball:
- Repeated gagging or retching without producing a hairball
- Loss of appetite lasting more than a day
- Lethargy or unusual withdrawal
- Constipation or diarrhea that persists
- Blood in vomit or stool
- A palpable lump in the abdomen
An intestinal blockage from a hairball is a surgical emergency. Several of the cases documented in veterinary literature involved cats that were dehydrated, hypothermic, and severely weakened by the time they reached treatment. Early intervention makes a significant difference in outcomes.
Reducing Hairball Frequency
The most direct prevention is removing loose fur before your cat can swallow it. Regular brushing, especially for long-haired breeds, reduces the volume of hair that ends up in the stomach. Daily brushing is ideal during heavy shedding seasons in spring and fall.
Diet also plays a meaningful role. Hairball-control cat foods typically contain higher levels of dietary fiber, and there are two types that work in different ways. Insoluble fiber (like cellulose) speeds up how quickly food moves through the intestines, which helps hair pass through before it can clump together. Soluble fiber (like psyllium husk) forms a gel that binds hair to food particles, making it easier for the stomach to push the hair forward into the intestines rather than letting it sit and accumulate.
Petroleum-based hairball lubricants, often sold as flavored pastes, work by coating the hair mass so it slides more easily through the digestive tract. These are a short-term tool rather than a long-term solution. If your cat is producing hairballs significantly more often than once every week or two, or if it has never had hairball issues and suddenly starts, the underlying cause is worth investigating rather than just managing the symptom.