How to Tell How Bad a Flea Infestation Is?

Any flea sighting is bad news, but it can be hard to know right off the bat if your furry friends just carried some adult fleas into your home or if the sign of fleas indicates a bigger problem.

Key Points:

  • Flea infestations can be harmful to both pets and humans, leading to health issues such as infections and lack of sleep.
  • Signs of a bad flea infestation include increased flea activity, excessive scratching, and the presence of flea feces.
  • To prevent and treat flea infestations, it is important to use flea control methods and keep the environment clean and free of fleas.

Signs of fleas can be as obvious as visible fleas and flea bites or as subtle as flea eggs and flea dirt being deposited around your home. But what constitutes a bad flea infestation, and how can you know for sure?

Without pulling out a magnifying glass and grabbing a flea comb, there are signs of fleas that let you know an infestation is worsening. Seeing these indicators before female fleas have filled all the hard-to-reach areas with flea larvae and eggs can save you time and hassle and might allow you to avoid having to bomb your entire house for a really bad infestation.

Read on to learn the signs that will tell you when your infestation has turned from bad to worse. 

Do Bad Flea Infestations Leave Signs?

There are clear signs that a flea infestation has grown bad, and if you keep an eye out, you can make sure that it doesn’t get worse. Infected fleas can pass on tapeworms and other diseases to your pets, and a severe infestation can negatively affect all people and animals in the home.

Even with regular flea control methods, there are times and conditions when an infestation may become possible. If this occurs, there will be obvious signs. 

Increased Flea Activity

A telltale sign of a growing flea infestation is more activity in pet bedding or where your pet sleeps. Flea collars and other flea control methods, including oral medication and topical medications, can wear off and, in the winter months, lead to hot spots of fleas with their flat bodies and amazing leaping abilities. 

Excessive Scratching

Female fleas that need blood to breed will bite pets incessantly until they are bloated and able to lay troves of eggs. Many flea species can lay hundreds of eggs in their short lives, and these baby fleas can grow up in a matter of weeks.

If you see a shortness of breath accompanying scratching, this is a sign of fleas and that your pet is suffering because of them. 

Flea Feces

Although it can be hard to spot, if you are noticing new accumulations of black specks in otherwise clean areas like on paper and window sills, then this could indicate that a heavy concentration of fleas is present.

Flea feces may also become visible in pet bowls and places like litter boxes that have fleas jumping around on them. 

Flea Dangers

Fleas are not just annoying, but their continued presence and consequential bites can lead to very real health issues for you and your pets. Aside from the discomfort of flea bites, constant scratching can cause wounds that may get infected.

These infections could become serious and require medical treatment.

Below are some more common dangers found in an environment for fleas.

DangerEffectHow to Prevent
TapewormsPrevent your pets from getting nutrients from their foodTreat pets with fleas using a flea shampoo or other pet-safe method, and give your pets deworming medication if tapeworm presence is confirmed
InfectionCan lead to fever and other dangerous conditions if left untreated and allowed to become dirty and gangrenousUse a gentle antiseptic to clean the wound and the area around an infected flea bite, then apply bandages or other covers to help the wound heal and keep it from being disturbed by your pets
Lack of SleepIndividual fleas can drive you crazy and prevent you from sleeping, but an entire infestation can be even worse, making it impossible for you to sleep soundly and leading to all sorts of health issuesTreat rooms where you sleep first and clean all bedding and put up safeguards to prevent fleas from re-enter to try and keep the areas you sleep infestation-free
RashesFlea bite dermatitis and rashes are common in the areas around flea wounds and can spread and cause other skin issues if not treatedFor instant flea bite relief, use warm water to clean the area and then apply a topical medication to rashes that are growing larger and redder
DiseasesInfection to humans from fleas is rare, but some diseases can spread to animals and then to humans through blood transmission from flea bites Keep areas where you and your pets dwell free of fleas, and makes sure to look out for common symptoms of illness or flu-like symptoms after being bitten by fleas
Flea Bite AllergyA severe reaction to being bitten by fleas can lead to anaphylactic shock and other health issues if you or your pets are allergic to themMake sure to always stay up-to-date on home and pet flea treatments if you or your animals suffer from flea bite allergies

What Causes a Flea Infestation?

Lots of things can cause a flea infestation, but the most common reasons account for almost all cases of a flea presence.

When an animal’s medication wears off, when the climate changes and causes bugs to breed in mass or rush to find shelter, and when old flea-infested secondhand materials are brought home, this is when fleas flourish. 


There are several ways pets can bring fleas into the home, and this is something that should always be considered if you have furry friends. If the flea medication or preventative pets rely on wears off, then it is possible that fleas may start hitchhiking.

They will occupy their bedding and multiply quickly. Pets playing with other pets from an infested home can also lead to more fleas than usual jumping onto your pet, and some are bound to follow them home. 

Old Clothes or Boxes

Beware old items that contain likely nests for fleas. Often when bringing in inherited or other heirloom materials, pests can become a problem. If the old boxes contain linens and fabrics, there is a good chance fleas, bed bugs, and probably cockroaches, too, have made their way inside over the years.

Always enact a quarantine around old materials in either the garage or outside to spray and kill bugs before bringing the rest indoors. 

Outdoor Fleas

Seasonal changes can spur fleas to find a warm place to hide from bad weather. If the fleas are able to find safety and a blood meal in your residence, then it is likely they will multiply, and other fleas and pests will make their way indoors.

This is more common in an unkempt lawn where fleas and other pests can hide and move around with ease and have access to wild animals on which to feed. 

How to Expel Fleas from Your Home?

An alternative way to get rid of fleas is to repel them from the home. Although this is a little more time-consuming and difficult to do than sealing the house and bombing all the bugs, it has the benefit of not introducing poison into your home and gives you more control of pest management than just using flea control spray.

This method involves outdoor treatments and then making inside your home less habitable for fleas and other pests, encouraging them to move out into your yard where biological control methods can wipe them out. 

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