Does Benadryl Really Help with Cat Allergies?

What Causes Cat Allergies

Cat allergies are caused by allergens produced by cats. The primary allergen is a protein called Fel d 1, which is found in cats’ saliva, skin flakes (dander), and urine (1). Fel d 1 is extremely lightweight and sticky, allowing it to spread easily through the air and stick to surfaces like carpets and furniture (2). When someone allergic to cats is exposed to Fel d 1, their immune system mistakenly identifies it as harmful and releases antibodies like histamine to attack it. This triggers an allergic reaction (3).

In addition to Fel d 1, cats produce other proteins in their saliva and skin flakes that can cause allergies as well. Male cats tend to produce more allergens than female cats. Kittens produce lower levels of Fel d 1, but as they age their allergen production increases (4). All cats produce allergens, even hairless breeds. There is no such thing as a truly hypoallergenic cat. Some cat breeds produce lower levels of allergens, but they can still cause reactions in people sensitive to Fel d 1 (5).




Symptoms of Cat Allergies

Symptoms of cat allergies are similar to other types of allergies. According to the American College of Allergy, Asthma and Immunology (, the most common symptoms include:

  • Sneezing
  • Runny or stuffy nose
  • Itchy, red or watery eyes
  • Facial pain and pressure from nasal congestion

Some people may also experience symptoms of asthma like coughing, wheezing, chest tightness or shortness of breath when exposed to cats. Rashes or hives may also develop on the face, hands or body.

According to the Mayo Clinic (, cat allergy symptoms can range from mild to severe depending on the individual. Even short exposure to cats can trigger symptoms in sensitive individuals.

Is Benadryl Effective Against Cat Allergies?

Yes, Benadryl can be an effective treatment for cat allergies. Benadryl contains an active ingredient called diphenhydramine, which is an antihistamine that blocks the effects of histamine in the body (1). Histamine is a chemical released by the immune system in response to allergens like cat dander or saliva. This release of histamine is what causes allergy symptoms like sneezing, runny nose, watery eyes, and itchiness.

Diphenhydramine blocks histamine receptors and prevents histamine from attaching to cells. This stops the immune system’s allergic response and relieves allergy symptoms (2). Multiple studies have shown that antihistamines like diphenhydramine are effective at reducing allergy symptoms from exposure to cats and other household pets (3).

However, the effects of antihistamines like Benadryl are typically temporary. They help manage allergy symptoms but don’t treat the underlying allergy. Once the medication wears off, symptoms can return if exposed to the allergen again. Antihistamines mainly provide short-term, temporary relief. Additional medications or treatments may be needed to fully manage cat allergies over the long term.




Proper Dosage of Benadryl

The standard dosage of Benadryl (diphenhydramine) for cats is 1 mg per pound of body weight, given 2-3 times a day. The most common dosage is 25-50 mg every 8 hours or 12 hours for an adult cat. The maximum total dosage per day is typically 150 mg.

According to veterinarians, the proper Benadryl dosage for cats is:1

  • 1-4 mg per kg body weight
  • 25-50 mg tablet every 8-12 hours
  • Max dosage of 150 mg per day

Cats metabolize Benadryl faster than humans, so the effects may wear off more quickly. That’s why veterinarians often recommend dosing 2-3 times per day rather than just once daily. Always follow your vet’s specific dosage instructions for your cat.

Use a dosage calculator or talk to your vet to determine the ideal Benadryl dose based on your cat’s weight. Never exceed the recommended maximum daily dosage.

Risks and Side Effects

Benadryl can cause a number of side effects, even when taken as directed. The most common side effects are:1, 2

  • Drowsiness – Benadryl can make you very sleepy, especially at higher doses. This is the most common side effect.
  • Dry mouth – Benadryl can reduce saliva production, leading to an uncomfortable dry feeling in the mouth.
  • Dizziness – Some people may feel lightheaded or dizzy after taking Benadryl.
  • Nausea – Nausea is another possible side effect of Benadryl use.

These side effects are usually mild, but can be more severe in older adults. Drowsiness in particular can increase the risk of falls. It’s important to be cautious of these effects when driving or operating machinery after taking Benadryl.

Alternative Allergy Medications

In addition to oral antihistamines like Benadryl, there are other types of medications that can help relieve allergy symptoms caused by cats:

Nasal sprays like fluticasone (Flonase) or triamcinolone (Nasacort) can reduce inflammation and congestion in the nasal passages. These corticosteroid nasal sprays work by suppressing the immune response that causes allergy symptoms. They are safe for daily use and more effective than oral antihistamines for nasal allergy relief.1

Eye drop antihistamine medications like olopatadine (Patanol) or ketotifen (Zaditor) can provide targeted allergy symptom relief for itchy, watery eyes caused by cat allergens. They work faster than oral antihistamines.2

Leukotriene modifiers like montelukast (Singulair) block the action of inflammatory leukotrienes to reduce allergy symptoms. This daily medication can help prevent allergy flare-ups.2

Steroid medications like prednisone may be prescribed for short-term use to quickly control severe allergy symptoms. Long-term oral steroid use has significant side effects, so it should be avoided if possible.1

These alternatives can provide more targeted allergy relief than oral antihistamines like Benadryl and may be preferable for some individuals. It’s best to discuss all medication options with a doctor to find the most effective treatment plan.

Allergy Shots

Allergy shots, also known as allergen immunotherapy, can substantially reduce allergic reactions to cats long-term. The treatment involves receiving injections of small, gradually increasing amounts of cat allergens over the course of 3-5 years. The goal is to desensitize the immune system to cat dander so the body no longer overreacts and causes allergy symptoms. Studies show allergy shots can reduce allergy symptoms and need for medication in people allergic to cats by up to 90% and benefits can last for years after stopping treatment.

According to the NIH, experimental cat allergy shots have shown to provide longer lasting relief than traditional allergy shots. The experimental version delivers smaller doses over a longer period of time. After 3 years, those who received the experimental shots had less severe allergic reactions to cats and had reduced their medication use by up to 50% more than those who received regular shots.

While allergy shots are very effective in the long-term, they require a significant commitment of 3-5 years of weekly injections followed by monthly boosters. Some insurance plans may not cover allergy shots. Allergy shots also carry a small risk of anaphylaxis, so shots must be administered under medical supervision. Overall, allergy shots can substantially improve quality of life for people with persistent cat allergies looking for long-term relief.


Other Ways to Manage Cat Allergies

In addition to medication, there are some other ways to help manage cat allergies without having to remove your feline friend from your home:

Vacuum and clean often – Cat dander containing allergens can settle deeply into carpets, furniture and bedding. Vacuuming carpets and mopping hard floors frequently can help reduce allergen levels. Use a vacuum with a HEPA filter for best results. It’s also important to wash bedding weekly in hot water to kill allergens.

Use HEPA filters – High-efficiency particulate air (HEPA) filters can trap cat allergens and remove them from circulating air. Use standalone HEPA filters or incorporate them into heating/cooling systems and air purifiers.

Limit exposure – Keep cats out of bedrooms and restrict them to only a few rooms, preferably with hard flooring. This helps limit allergen exposure in primary living areas. Washing hands after contact can also reduce allergic reactions.

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Considerations for Children

When giving Benadryl to children for cat allergies, it’s important to use a lower dosage and consult a pediatrician first. The recommended dosage of diphenhydramine for children ages 6-12 years old is 6.25 mg to 25 mg every 4 to 6 hours. For children ages 2-6 years old, the dosage is 3.125 mg to 12.5 mg every 4 to 6 hours. Always check with your child’s doctor before giving them any medication, as the proper dosage depends on the child’s weight and age.

Some side effects like drowsiness may be more pronounced in children. It’s best to give the first dose at home so you can monitor for potential side effects. Avoid giving more than the recommended dosage, as overdose can occur more easily in children. Track when each dose is given and watch for any worrisome symptoms like excessive sleepiness, confusion, hallucinations or fast/irregular heartbeat. Contact your pediatrician right away if your child experiences signs of overdose.

While Benadryl can provide temporary relief, it shouldn’t be used long-term to manage children’s cat allergies. Work with your pediatrician to find safer long-term treatment options like allergy shots, nasal sprays or other medications. Keeping your home clean and limiting exposure to cats can also help reduce allergy symptoms without medication.

With proper precautions, short-term Benadryl use can help relieve allergy symptoms in children when exposure to cats can’t be avoided. But it’s always wise to consult your pediatrician first and use the lowest effective dose.

When to See a Doctor

In most cases, cat allergies can be managed at home with over-the-counter medications and lifestyle changes. However, you should see a doctor right away if you experience any of the following severe allergy symptoms:

  • Trouble breathing – This includes wheezing, feeling short of breath, chest tightness, or coughing.
  • Swollen throat – Swelling in the mouth, tongue, or throat area can be dangerous and block breathing.
  • Anaphylaxis – Signs of a life-threatening allergic reaction include swelling of the face/lips, trouble swallowing, dizziness, and fainting.
  • Severe skin reaction – Hives all over the body, intense itching, and swelling/redness in the skin.

If you experience any severe symptoms after exposure to cats, seek emergency care right away. Milder symptoms can typically be treated at home, but recurrent or persistent symptoms should be evaluated by an allergist. They can help identify your allergy triggers and provide long-term treatment options like allergy shots or medications.

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