Can Cat Fleas Make You Sick? The Surprising Truth About Flea Bites


Cat fleas are small parasitic insects that feed on the blood of cats. Although cat fleas prefer cats as hosts, they will also readily bite and feed on humans. While cat fleas themselves are just a nuisance, their bites can cause allergic reactions or skin irritation. More concerning, however, is the fact that cat fleas can transmit diseases from cats to humans, known as zoonotic diseases. Some of the diseases carried by cat fleas that pose a risk to human health include bartonellosis (cat scratch disease), typhus, and plague. Understanding the health risks posed by cat fleas and how to prevent exposure is important for protecting human health, especially for pet owners.

What Are Cat Fleas?

Cat fleas (Ctenocephalides felis) are small, wingless, parasitic insects that live on cats, dogs, and other mammals. They are external parasites, meaning they live on the skin and fur of their hosts and feed on their blood (1).

The cat flea goes through four life stages: egg, larva, pupa, and adult. Adult female fleas lay eggs on the host which fall off into the environment. The eggs hatch into larvae which feed on organic debris. The larvae then spin a cocoon and develop into pupae. When the pupa senses vibrations, heat, or carbon dioxide from a potential host, it emerges as an adult flea. The entire life cycle from egg to adult usually takes 2-3 weeks (2).

Adult cat fleas are only about 1/16 to 1/8 inches long. They are laterally flattened which allows them to easily move through fur. They have strong hind legs adapted for jumping onto hosts. Cat fleas can jump up to 7 inches vertically and 13 inches horizontally (1). They have piercing-sucking mouthparts used to bite the host and feed on blood.

Cat fleas survive by ingesting blood from their hosts. A flea can live 1-2 months and a female can lay up to 50 eggs per day. Cat fleas do not live or reproduce directly on humans but sometimes bite people opportunistically (2).

Diseases Transmitted by Cat Fleas

Cat fleas can transmit several diseases to humans including plague, murine typhus, and bartonellosis. The oriental rat flea (Xenopsylla cheopis) and cat flea (Ctenocephalides felis) can transmit plague caused by the bacterium Yersinia pestis. This potentially fatal disease manifests with fever, chills, weakness, and swollen lymph nodes (source).

Murine typhus is caused by Rickettsia typhi and Rickettsia felis bacteria transmitted by infected fleas. Symptoms include fever, rash, headache, and muscle pains. Without treatment, severe complications like pneumonia, meningitis, and kidney failure can occur (source). The cat flea is the main vector of R. felis (source).

Bartonellosis, also called cat scratch disease, is caused by Bartonella henselae bacteria. Cat fleas and oriental rat fleas transmit it through bites and scratches. Swollen lymph nodes near the injury site are characteristic (source).

Allergic Reactions

Some people may experience allergic reactions to cat flea bites. These allergic reactions can range from mild to severe. According to Orkin, the most common allergic reaction is excessive itching and irritation at the bite site. The itching is often more intense than would be expected from a typical insect bite. Some people may also develop hives or a rash around the bite.

More severe allergic reactions are possible as well. Some individuals can experience anaphylaxis from cat flea bites. Anaphylaxis is a life-threatening reaction characterized by swelling of the throat and airways, difficulty breathing, lowered blood pressure, dizziness, and fainting. If a cat flea bite triggers anaphylaxis, immediate medical treatment with epinephrine is required.

According to Dutch, other symptoms of a cat flea bite allergy can include swelling at the bite site, swollen lymph nodes, fever, and fatigue. Repeated exposure to cat flea bites may cause the allergy symptoms to become progressively worse over time.

To manage a cat flea bite allergy, medications like antihistamines and topical steroid creams may help control itching and swelling. Allergen immunotherapy may also be an option to desensitize the immune system. Of course, the most effective way to prevent allergic reactions is to control flea infestations and avoid flea bites altogether.

Skin Irritation and Infection

Flea bites can cause significant skin irritation and itching in both cats and humans. Fleas have saw-like mouthparts that allow them to easily pierce through skin and feed on blood. This process irritates the skin and causes red, swollen, itchy welts to appear.

According to the Cleveland Clinic, flea bites usually occur around the ankles and legs as this is where fleas can most easily reach skin. The bites are intensely itchy and scratching them can lead to infection 1. Repeated scratching breaks the skin integrity allowing bacteria to enter and cause secondary infections. Signs of infection include increased redness, swelling, pain, and pus.

To treat flea bite skin irritation, the Cleveland Clinic recommends cleaning the bite with soap and water, using hydrocortisone cream, and avoiding scratching. Keeping the skin clean and intact is key to preventing infections. If signs of infection develop, seeing a doctor for antibiotic treatment is recommended.


Flea infestations can cause anemia in both pets and humans. Anemia is a condition where there is a decrease in red blood cells or hemoglobin, resulting in inadequate oxygen delivery to tissues. In severe flea infestations, the loss of blood from flea bites can lead to anemia.

According to an article on, “Flea bite anemia: If enough fleas infest your pet, especially young or small animals, they can lose enough blood to become anemic.” [1] The same can occur in humans, especially children, if they are exposed to a large number of flea bites over time.

A case report published in the National Center for Biotechnology Information discussed a 6-year-old boy who developed severe anemia likely caused by flea bites, though other factors like poor nutrition contributed. [2] Symptoms of flea bite anemia can include fatigue, pale skin, dizziness, and shortness of breath.

Treatment for flea bite anemia involves eliminating the flea infestation and replenishing iron levels through diet or supplements. In severe cases, blood transfusions may be necessary. Preventing flea infestations in pets and promptly treating them can reduce the risk of humans developing flea bite anemia.

Psychological Effects

A flea infestation can have a significant psychological impact on humans. Some people develop delusory parasitosis, a condition involving a false belief that bugs are infesting the skin [1]. Even without this extreme reaction, fleas can cause anxiety, stress, insomnia, and obsessive behaviors as people become preoccupied with eliminating the infestation [2]. Constant itching and lack of sleep from flea bites can affect mood and concentration. Some people feel embarrassed or ashamed about having fleas in their home. In severe cases, the psychological effects of a flea infestation can lead to depression or declining mental health [3]. Getting rid of fleas quickly and thoroughly is important to alleviate these psychological effects.


Treatment for flea bites focuses on providing relief from itching and preventing infection. Some options include:

  • Over-the-counter anti-itch creams containing ingredients like hydrocortisone or pramoxine can provide relief from itching and inflammation. These are applied topically to the affected areas. Healthline
  • Oral antihistamines like diphenhydramine (Benadryl) can help reduce itching by blocking histamine reactions. These provide systemic relief from itching. Cleveland Clinic
  • Applying a cold compress or ice pack to bites can reduce swelling and itching. The cold temperature helps override itching sensations. Better Health Channel
  • Keeping the skin clean and avoiding scratching can prevent infection. Gentle cleansing with mild soap and water can remove irritants. Better Health Channel

Preventing flea infestations is key to avoiding bites. This may involve treating pets, vacuuming regularly, washing bedding on hot cycles, and using flea control products in the home. Flea collars, spot treatments, shampoos, sprays, and foggers can eliminate fleas on pets and in living spaces.

When to See a Doctor

You should see a doctor for flea bites if you experience any of the following symptoms:

  • Severe itching or pain that does not respond to over-the-counter treatments
  • Signs of a skin infection, such as oozing, increasing redness, swelling, warmth, or red streaks
  • Difficulty breathing or swallowing, which may indicate a severe allergic reaction
  • Fever, which could signal a secondary infection
  • Extensive skin irritation or multiple bites
  • Anemia from excessive blood loss in cases of extreme infestation
  • Significant fatigue, lethargy or weakness from blood loss
  • Enlarged lymph nodes near the bite areas

Seeking timely medical treatment is important for severe reactions and infections. The doctor can provide medications to ease symptoms and treat any underlying illness.


Cat fleas can be more than just a nuisance – they can transmit diseases and cause uncomfortable health issues in people as well. Key points covered in this article include:

  • Cat fleas can spread diseases like typhus, plague, and bartonellosis to humans through their bites.
  • People who are allergic may experience severe itching, rashes, and anaphylaxis from flea bites and saliva.
  • Flea dirt and bites can lead to painful skin irritation, infections, and anemia if left untreated.
  • The parasites can also cause anxiety, sleeplessness and other psychological issues.

Treating flea bites, controlling infestations, and preventing contact are crucial to avoid these potential health problems. While fleas prefer cats, they will readily bite humans and can transmit serious diseases as well as cause uncomfortable symptoms. Being aware of these risks allows pet owners to protect themselves and their families from complications due to cat fleas in their home.

Scroll to Top