How Do Cats Get Fleas? The Unlikely Sources That Can Cause Infestations

April 15, 2025

You might be surprised—and frustrated—to discover your indoor cat has fleas. After all, how do cats get fleas if they never go outside? It’s a common misconception that indoor cats are completely safe from fleas. Unfortunately, fleas are expert hitchhikers, capable of infiltrating even the cleanest homes. These tiny pests are persistent and opportunistic, finding creative ways to enter your home and latch onto your unsuspecting feline.

How Fleas Spread: Understanding Their Movements

Fleas are small, wingless parasites that feed on the blood of mammals and birds. Once they find a host, they settle in to feed and reproduce rapidly. But how do cats get fleas in the first place—especially indoor-only cats? To understand how these pets invade your home, it can be helpful to learn about their lifecycle and movements.

The flea lifecycle consists of four stages: egg, larva, pupa, and adult. A single female flea can lay up to 50 eggs per day, dropping them onto your cat or into your home environment. These eggs can also fall off the host and scatter into your carpets, bedding, and upholstery. Within days, they hatch into larvae. These larvae live off eating organic matter before eventually transforming into pupae. After weeks or months, pupae mature into adults.

Adult fleas can jump impressive distances—up to 100 times their body length—allowing them to latch onto animals or even humans. Once they’ve found a host, adult fleas begin feeding almost immediately. As soon as two days after consuming blood from your cat, females can start to lay eggs of their own, continuing the cycle. Because of their rapid reproduction, a minor flea problem can quickly become a significant infestation if not addressed.

Can Indoor Cats Get Fleas?

Absolutely! Even if your cat never leaves the house, fleas can still find a way in. There are several often-overlooked ways your indoor cat might end up with fleas.

Human Carriers

You may unknowingly bring fleas into your home. Fleas can cling to your clothing, shoes, bags, or other items after you’ve spent time outdoors or in a new environment—whether hiking, visiting a friend’s pet or simply walking through a grassy area. By the time you notice itchy bites or see your cat scratching, fleas could already be multiplying.

How to minimize this risk:

Inspect your clothing and belongings after spending time outdoors
Regularly wash outdoor attire
Designate an area near the door for removing shoes

Rodents and Other Wildlife

Rodents like mice, rats, and squirrels can carry fleas. If these critters make their way inside, they can unknowingly introduce fleas into your home.

How to minimize this risk:

Seal any cracks or openings in your home’s exterior
Store food securely
Maintain cleanliness to deter wildlife

Cracks and Openings

Fleas are tiny and resourceful. They can slip through the smallest openings, including gaps under doors or tears in window screens.

How to minimize this risk:

Regularly inspect and repair entry points
Ensure windows and doors fit securely
Replace or repair damaged screens

Secondhand Items

Used furniture, rugs, or bedding can be an unexpected source of fleas. If these items came from an infested environment, they could carry flea eggs or larvae.

How to minimize this risk:

Thoroughly inspect and clean secondhand items
Wash fabrics in hot water
Vacuum rugs or upholstered items before use

Apartment Complexes and Shared Spaces

In multi-unit buildings, fleas can travel between apartments through vents, walls, or shared hallways.

How to minimize this risk:

Talk to your property manager about pest control measures
Coordinate pest prevention efforts with neighbors if possible

Other Pets

If you have a dog or other pets that go outside, they can pick up fleas and bring them inside, where the fleas can jump onto your indoor cat.

How to minimize this risk:

Ensure all pets in your home are on a flea prevention program

Minimizing the Risk of Flea Infestations for Indoor Cats

Preventing fleas is far easier—and less stressful—than treating an infestation. Taking proactive steps can help protect your indoor cat and home.

Administer Flea Preventatives

Even indoor cats can benefit from ongoing flea prevention. Year-round treatment can safeguard against serious health issues caused by untreated infestations, including skin irritation, allergies, anemia, and even infections like tapeworm. In severe cases, secondary bacterial infections can even require antibiotics for your cat to fully heal.

Talk to your veterinarian to choose the right product or combination of treatments—oral or topical treatments, shampoos, or flea collars
Turn to Mixlab’s online pet pharmacy for leading flea and tick preventatives with free, next-day delivery

Topical Flea Preventatives

Topical flea preventatives offer long-lasting protection and are applied directly to the skin, typically between your cat’s shoulder blades. These treatments are absorbed through your cat’s skin and work by disrupting the flea’s nervous system. The most common flea preventatives for cats are topical.

Prescription options include:

Bravecto® (fluralaner): A topical for cats that belongs to the isoxazoline class. It provides up to 12 weeks of protection by blocking GABA- and glutamate-gated chloride channels, causing overstimulation of the flea’s nervous system while remaining safe for your cat.
Revolution Plus® (selamectin and sarolaner): A broad-spectrum topical treatment that not only kills fleas but also prevents heartworms, ear mites, and certain intestinal parasites.

Over-the-counter options include:

Advantage II® (imidacloprid and pyriproxyfen): A topical that kills adult fleas on contact and prevents flea eggs and larvae from developing, breaking the flea lifecycle.
Frontline Plus® (fipronil and (S)-methoprene): A popular waterproof topical treatment that kills fleas, ticks, and chewing lice, providing month-long protection.

Oral Flea Preventatives

Oral flea preventatives work systemically, meaning the active ingredient is absorbed into your cat’s bloodstream. Once a flea bites, it ingests the medication and is quickly killed. These preventatives are convenient if you’re looking to avoid topical residue.

Prescription options include:

Credelio® (lotilaner): A chewable tablet for cats in the isoxazoline class, targeting fleas at the neurological level for month-long protection.
Comfortis® (spinosad): A fast-acting chewable flea preventative that targets nicotinic acetylcholine receptors, leading to rapid flea elimination within four hours (though fleas begin dying within 30 minutes).

Over-the-counter options include:

CAPSTAR® (nitenpyram): An oral flea treatment that starts killing fleas within 30 minutes and is ideal for immediate flea infestations but requires a long-term follow-up preventative.
Program® (lufenuron): A flea growth inhibitor that prevents flea eggs from hatching, disrupting the flea life cycle when used regularly. It does not, however, kill adult fleas.

Vacuum Regularly

Once introduced to your home, flea eggs and larvae easily hide in carpets and upholstery. Regular vacuuming can help break the flea lifecycle.

Focus on areas where your cat spends the most time
Dispose of vacuum bags or empty canisters promptly

Wash Bedding

Wash your cat’s bedding regularly, including blankets and any soft surfaces they sleep on.

Use hot water to kill any flea lifecycle stages
Consider washing other fabrics your cat uses

Seal Entry Points

Inspect your home for cracks, gaps, or openings that could allow fleas or wildlife inside.

Repair damaged screens and doors
Seal up any holes or entry points

Use Home Treatments

Preventative treatments can help protect your cat from fleas.

Use sprays or treatments specifically designed for indoor use
Make sure any treatments you use are safe for pets

Inspect Secondhand Items

Be cautious when bringing used furniture or fabrics into your home.

Inspect all items thoroughly
Clean or vacuum items well
Wash any removable fabrics

Have Visitor Awareness

Guests who own pets may unknowingly carry fleas into your home.

Politely ask about their flea prevention routines
Encourage removing shoes or outer layers if they've been around pets or in flea-prone areas

Understanding Potential Sources of Re-Infestation

Fleas are notoriously persistent. If you miss one part of the flea lifecycle, you could find yourself battling a new infestation weeks or even months later.

So, how do cats get fleas multiple times? Here are common ways re-infestations happen:

Lack of Thorough Cleaning: Missing hidden flea eggs or larvae in carpets, furniture, or bedding.
Not Treating All Pets: If only one pet is treated, fleas can continue to thrive on untreated animals.
Not Treating Communal Areas or the Yard: Fleas can jump onto your cat during time spent in untreated spaces.
Missed Preventative Treatments: Skipping a dose of flea medication can leave your cat vulnerable to new fleas.

Trustworthy Flea and Tick Protection for Indoor Cats

The good news? Protecting your indoor cat is easy with Mixlab. If your veterinarian doesn’t carry the preventatives you need, we got you. We offer a full range of flea and tick preventatives depending on your cat’s needs. With free, next-day delivery, you can rest easy knowing your cat is protected without the stress of an unexpected infestation. Simply submit your prescription online or contact our team.