The Cat Allergy Countdown. How Long Until Symptoms Appear

What is a cat allergy?

A cat allergy is caused by an overreaction of the immune system to proteins found in cat dander (scales of old skin cells), saliva, or urine (1). When someone with a cat allergy comes into contact with these allergens, their immune system mistakenly identifies them as harmful invaders. The body then releases chemicals like histamine to defend against the perceived threat.

This immune system response results in the symptoms associated with cat allergies. Common symptoms include (2):

  • Sneezing
  • Itchy, watery eyes
  • Runny nose

For some, symptoms may progress to include coughing, wheezing, chest tightness, and shortness of breath in more severe reactions.

Who is at risk for developing cat allergies?

There is really no way to predict who will develop cat allergies. However, people with asthma or other allergies are more likely to be allergic to cats. According to the Mayo Clinic, more than 30% of people with allergies develop allergies to cats and dogs. Cat allergies usually develop in childhood or during the late teens/early adulthood years.

The immune system of a person with cat allergies overreacts to proteins found in cat saliva, skin cells, and urine. These proteins are called allergens. When allergens come in contact with the immune system, it triggers antibody production and release of histamine, which leads to allergy symptoms. People can be allergic to one or multiple cat allergens. There are 5 known cat allergens identified as Fel d 1, Fel d 2, Fel d 3, Fel d 4, and Fel d 7.

According to WebMD, factors that may increase the risk of developing cat allergies include:

  • Having other allergies like dust mites, pollen, or mold
  • Having asthma
  • Having exposure to cats at an early age
  • Having a parent with animal allergies

While cat allergies are common, it’s impossible to predict who will develop them. Those with existing allergies are at higher risk. Cat allergies tend to develop in childhood through early adulthood upon exposure to cats.


How long before cat allergy symptoms appear?

Cat allergy symptoms can develop quickly after exposure to cats or may take years to appear. Some people will react after only 1-2 exposures to cats, while others don’t develop symptoms until they’ve lived with a cat for many years. There are a few factors that influence how quickly cat allergy symptoms start:

Genetics – Those with a family history of allergies are more likely to develop cat allergies faster when exposed to cats. If both parents have allergies, their children have about a 70% chance of developing allergies as well.

Previous allergy history – People who already suffer from one type of allergy, like hay fever or asthma, have an increased risk of developing cat allergies sooner when exposed to cats. Their immune systems are already prone to overreacting.

Frequency of exposure – The more often someone is exposed to cats, the quicker allergy symptoms may appear as the immune system has more chances to react. Those who live with cats daily versus visiting occasionally tend to react faster.

In summary, some people react after minimal exposure due to genetic risks, while others take years of frequent interaction before developing cat allergy symptoms. Testing can help diagnose true cat allergies versus temporary irritation.

Acute vs chronic cat allergies

Cat allergies come in two main forms: acute and chronic.

Acute cat allergies involve a new allergy that develops relatively quickly after exposure to cats. With acute cat allergies, allergy symptoms like sneezing, runny nose, and itchy eyes typically appear within hours or days of exposure to cats.

In contrast, chronic cat allergies are long-term allergies that take much longer exposure to cats to develop. People with chronic cat allergies are often exposed to cats for weeks, months or even years before allergy symptoms start to appear. This is because it takes time for the immune system to become sensitized to cat allergens through repeated exposure.

With chronic cat allergies, symptoms also tend to worsen gradually over time as sensitivity increases. Acute allergies involve more immediate symptom onset. Both types involve an overreaction of the immune system to cat proteins.

Allergy Testing for Cats

There are several options for allergy testing in cats to help determine the specific allergens triggering symptoms:

The most common allergy test for cats is the skin prick test, also known as intradermal testing. This involves injecting small amounts of suspected allergens like pollens or dust mites into the cat’s skin and evaluating the reaction. A positive reaction is indicated by redness and swelling at the injection site

Blood tests are another option, analyzing the cat’s blood sample for IgE antibodies to different allergens. Companies like LabCorp offer specialized cat allergy blood tests to test for sensitivity to common environmental and food allergens.

For suspected food allergies, vets may recommend an elimination diet or oral food challenge, where the cat is fed a hypoallergenic diet followed by gradual reintroduction of ingredients to check for reactions.

Treating cat allergies

There are several ways to treat cat allergies. Some common medical treatments include:

  • Antihistamines like cetirizine (Zyrtec), fexofenadine (Allegra), and loratadine (Claritin) can help reduce allergy symptoms like sneezing and itchy eyes (
  • Nasal steroid sprays such as fluticasone propionate (Flonase Allergy Relief) and triamcinolone (Nasacort Allergy 24HR) can reduce inflammation in the nasal passages (
  • Allergy shots or immunotherapy involves getting injections of small amounts of cat allergens over time to desensitize your immune system. This can significantly reduce allergy symptoms over the long run (

The most effective treatment is removing the cat from the home, which eliminates exposure to the allergens. However, this may not be an ideal option for cat owners. Keeping the cat out of the bedroom and using HEPA air filters can help reduce exposure.

Tips for living with a cat allergy

Living with a cat allergy can be difficult, but there are ways to manage the symptoms. Some tips for co-existing with cats include:

Keep the cat out of the bedroom. Since you spend many hours sleeping in the bedroom, it’s important to make this room a cat-free zone. Use HEPA air cleaners in the bedroom and keep the door closed.

Vacuum and groom the cat regularly. Vacuuming twice a week can significantly reduce airborne allergens. Additionally, brushing or wiping your cat down regularly can remove a lot of allergen-containing dander and saliva on their fur.

Consider getting a low-allergen cat breed. While no cat is completely non-allergenic, some breeds like the Sphynx, Russian Blue, and Devon Rex tend to produce fewer allergens. Their coats produce less dander.

Other tips include using high-efficiency filters in heating/AC systems, washing hands after petting cats, and wearing an allergy mask when cleaning litter boxes or pet beds. Talk to an allergist about additional ways to manage allergy symptoms.

Differences between cat allergies and colds

While cat allergies and colds share some similar symptoms like a runny nose and sneezing, there are some key differences between the two conditions:

Cat allergy symptoms tend to persist as long as exposure to the cat continues. Colds on the other hand are temporary viral illnesses that go away on their own within 7-10 days.[1]

Itchy, watery eyes are more characteristic of cat allergies. Colds may cause watery eyes, but not usually itchiness.[2]

Fevers are more common with viral colds than with cat allergies. Allergies themselves do not cause fever.[3]

The symptoms of cat allergies come on rapidly with exposure to a cat and go away once the exposure is removed. Colds take a few days after viral exposure to develop symptoms.

Finally, allergy testing can confirm cat allergies by testing for IgE antibodies produced in response to cat proteins. There are no specific tests for confirming colds.

Knowing the differences between cat allergy and cold symptoms can help identify the cause and direct appropriate treatment.


Cross-reactivity with other allergies

People who are allergic to cats may also experience cross-reactivity with allergens from other animals. This occurs because the immune system recognizes similar proteins in multiple allergens and reacts to all of them. The authors in explain that cross-reactivity happens when the body’s immune system identifies similar protein components across different substances.

Those with cat allergies often have higher rates of allergic reactions to other pets like dogs, horses, and rabbits. The proteins in saliva and skin dander from these animals contain cross-reactive allergens that can trigger symptoms. People may not realize they are also allergic to other pets until exposure triggers a reaction.

In some cases, people can even have life-threatening anaphylactic reactions to animals they have previously tolerated after their cat allergy has increased in severity over time. It’s important for people with cat allergies to be aware of potential cross-reactivity so they can take precautions and manage their exposure to other pets that may trigger allergy symptoms.

Outlook for cat allergy sufferers

While there is no cure for cat allergies, treatments can help manage symptoms and improve quality of life for allergy sufferers ( Some people may outgrow their allergy over time, especially if it first develops in childhood. However, cat allergies that persist into adulthood are likely to be lifelong. For severe cat allergies that cause major disruptions to daily living, rehoming the cat may ultimately be necessary. Still, various medical treatments, environmental changes, and lifestyle adjustments can enable many cat lovers to continue living with their feline companions despite allergy challenges.

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