Do Cat Allergies Progressively Worsen? The Answer May Surprise You


Cat allergies are a common condition that affect millions of people around the world. They occur when a person’s immune system overreacts to proteins found in cat saliva, urine, or dander (skin flakes). When exposed to cat allergens, the body releases histamine and other chemicals that cause allergy symptoms like sneezing, runny nose, watery eyes, coughing, wheezing, and skin rashes. In severe cases, cat allergies can trigger asthma attacks or anaphylaxis. The symptoms usually begin soon after exposure to a cat and can range from mild to severe. With continued exposure over time, some people do experience worsening allergy symptoms. In this article, we will explore the causes, progression, testing, and management of cat allergies.

Causes of Cat Allergies

Cat allergies are caused by proteins found in cats’ dander (skin flakes), saliva, and urine (WebMD). The main allergen is a protein called Fel d 1, which is produced in cats’ sebaceous glands and spread through shedding hair and skin cells. When cats groom themselves, Fel d 1 gets deposited onto their fur. As the fur sheds, the allergens are released into the environment. Saliva containing Fel d 1 is also transferred to cats’ fur when they lick themselves. Fel d 1 is extremely lightweight and can remain airborne for long periods. It also sticks to surfaces, fabrics, and clothing easily. Additionally, cats’ urine contains allergens like protein Fel d 4. Exposure to any of these allergens can trigger allergic reactions in sensitive individuals.

Allergen Exposure Over Time

Repeated exposure to cat allergens over time can make cat allergies worse, according to experts. This is because the immune system builds up antibodies against the allergen with each new exposure (Webmd). With continued exposure over months or years, the antibody levels accumulate and can trigger heightened allergic reactions. Even low-level, routine exposure allows antibody levels to remain elevated, priming the immune system for stronger responses to future encounters with cat dander or saliva. So living with a cat day after day means the allergies are unlikely to improve and will probably intensify over time. One study found that high allergen doses can provoke an immune response that enhances, rather than suppresses, allergic reactions (NCBI). For sensitive individuals, there is no “safe” threshold of cat allergen exposure. The more they are exposed, the more severe the allergic response can become.

Allergy Progression

Cat allergies can get worse over time, particularly as children reach adolescence and adulthood. There are a few reasons for this:

During puberty, the immune system undergoes changes that can make allergies more severe. Hormonal shifts influence immune responses, and adolescents may develop new allergies or find existing ones get worse (Sparkes, 2022).

With ongoing allergen exposure, the immune system mounts larger inflammatory responses over time. Each reaction releases antibodies and chemicals that sensitize the body further (The Atlantic, 2022).

Adults spend more time indoors around allergen sources than children. More exposure means more reactions. Additionally, the lungs’ defenses decline with age, compounding allergy effects (Satyaraj et al., 2019).

In essence, cat allergies can worsen from childhood into adulthood due to natural immune system changes, ongoing allergen exposure, and lifestyle factors.

Allergy Severity

The severity of cat allergies can vary greatly between individuals based on environmental factors. According to WebMD, exposure to allergens like cat dander over time can cause allergies to become more severe if left unchecked (source). Things like the number of cats in the home, how much time is spent around cats, air circulation and filtration, and diligence of allergy management all impact allergy progression.

For example, someone living in a small apartment with multiple cats and poor air circulation may experience a dramatic worsening of allergy symptoms over months or years of continuous exposure. On the other hand, someone who lives in a large, clean home with just one cat and uses air purifiers regularly may maintain a consistent level of mild allergy symptoms.

The key is to minimize allergen exposure as much as possible through measures like washing hands after petting cats, using High Efficiency Particulate Air (HEPA) filters, vacuuming frequently, and washing bedding regularly. With proactive allergy management, symptom progression can often be prevented.

Managing Allergies

There are several ways to manage cat allergies and reduce allergy symptoms over time:


Avoiding exposure to cats is the most effective way to prevent allergy symptoms. Keeping cats out of the bedroom and restricting them to certain areas of the home can help reduce exposure (Source 1). Vacuuming frequently, washing hands after contact, and using HEPA air filters can also minimize allergen levels.


Antihistamines, decongestants, nasal sprays, and allergy eye drops can provide relief from allergy symptoms. Allergy medication should be taken regularly during allergy season. Talk to a doctor about prescription medications for more severe cat allergies (Source 2).


Allergy shots or sublingual immunotherapy tablets/drops containing cat allergens can gradually build tolerance over time. Immunotherapy is often effective at reducing allergy symptoms and the need for medication (Source 3). Treatment is usually given for 3-5 years.

Allergy Testing

Two primary types of tests are used to diagnose cat allergies: skin prick tests and blood tests. According to the Mayo Clinic, skin prick testing involves exposing the skin to small amounts of cat allergen extracts (1). This causes a small, itchy red bump to form if a person is allergic. The results usually come back within 15 minutes.

Blood tests can also detect and measure allergy antibodies to cat dander. As described by the Asthma and Allergy Foundation of America (2), an allergist will take a blood sample and send it to a lab, where it is mixed with cat allergen. The results indicate if antibodies reacted, signaling an allergy. Blood tests take longer to complete but can help confirm skin prick results.

Allergy testing can identify sensitivity to certain cat allergens. This helps allergy sufferers know if their symptoms are caused specifically by cats or other triggers. Testing also aids in developing treatment plans tailored to the individual.


Fel d 1, the major cat allergen, can trigger allergic reactions in individuals sensitized to other furred pets like dogs. This is due to molecular similarity and cross-reactivity between Fel d 1 and Can f 1, the main dog allergen (Reininger et al., 2007). While both proteins are produced in salivary and sebaceous glands, Can f 1 has only about 57% sequence identity to Fel d 1 (Chan et al., 2018).

So some individuals allergic to cats may also react to dogs. However, the majority of cat-sensitized patients are not clinically reactive to dogs. Pure dog allergy with no cat sensitivity is also common. So cross-reactivity exists between cat and dog allergens but does not fully explain pet allergies (van Hage, 2023).

Reininger, R., Mutschlechner, S., Swoboda, I., Focke, M., Valenta, R., & Spitzauer, S. (2007). Detection of an allergen in dog dander that cross-reacts with the major cat allergen Fel d 1. Clinical & Experimental Allergy, 37(1), 116-124.

van Hage, M. (2023). Emphasizing the role of molecular allergy diagnostics. Clinical and Experimental Allergy.

Long-Term Outlook

There is currently no cure for cat allergies, but treatments can help manage symptoms and improve quality of life over the long term. According to the Mayo Clinic, allergy shots, medications, and avoidance of triggers can “provide long-term relief of allergy symptoms” (source). With commitment to treatment, many people are able to keep living with cats despite their allergies.

Allergy shots, also known as immunotherapy, work by gradually exposing the immune system to cat allergens over 3-5 years. Research shows this can provide lasting relief even after treatment is discontinued. A study from the National Institutes of Health found experimental cat allergy shots led to a sustained improvement in symptoms and quality of life for at least 1 year after stopping treatment (source).

While not a cure, diligent management with medications and allergen avoidance alongside possible allergy shots means cat allergies don’t have to worsen over the long term. Working closely with an allergist can help find an effective treatment regimen for each individual.


In summary, cat allergies are caused by exposure to specific proteins found in cat dander, saliva, and urine called allergens. For those with cat allergies, symptoms may get progressively worse over time with continued exposure as the immune system becomes more sensitized. However, the severity can vary depending on the level of allergen exposure and individual sensitivity. While there is no cure, symptoms can be managed through medications, allergen avoidance, and immunotherapy. Testing is important to confirm allergy triggers. It’s also possible to develop additional cat-related allergy sensitivities over time through cross-reactivity. The long-term outlook depends on actively controlling exposure. With proactive allergy management and minimal contact with cats, it may be possible to keep symptoms from worsening significantly.

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