Understanding Benadryl® for Cats

Benadryl is one of those household names that most people recognize, often reaching for it when allergies flare up, a pesky rash appears, or when motion sickness strikes.

It’s a go-to over-the-counter medication for humans, used to treat a variety of symptoms like sneezing, itching, watery eyes, and even mild allergic reactions. Benadryl for cats is used in much the same way as it is for humans.

Benadryl is the name-brand medication for the antihistamine drug called diphenhydramine. It is not created for use in pets, although many veterinarians will recommend it.

Is Benadryl Safe for A Cat?

The short answer is that Benadryl can be safe for a cat—but only under the right circumstances and with proper veterinary guidance.

Veterinarians sometimes recommend Benadryl for cats, but it's not a one-size-fits-all solution. A cat has a unique metabolism, and its body processes medications differently than humans or even dogs.

This means that while Benadryl can be helpful, it must be used cautiously to avoid potential side effects.

What is Benadryl?

Benadryl is the brand name for Diphenhydramine Hydrochloride drug, an antihistamine medication that blocks the effects of histamine in your body.

What are Histamines & Antihistamines?

Histamine is a chemical released by the immune system during an allergic reaction, causing symptoms like itching, swelling, and redness.

Diphenhydramine Hydrochloride (HCL) blocks histamine and helps to alleviate uncomfortable symptoms of an allergic reaction like runny nose and sneezing, making it easier to breathe, sleep, or just get through the day without itching from insect bites or a bee sting.

Benadryl Use in Cats

While Benadryl is formulated for humans and it’s not FDA-approved for pets, veterinarians recommend it for cats under certain circumstances.

Veterinarians may recommend Benadryl when cats are dealing with allergies, motion sickness, sleep problems, or easing symptoms of anxiety in some cases. 

Benadryl to a cat isn’t as straightforward as it is for humans. A cat has unique biology with its own specific needs, and what works for us doesn’t always work for it. That’s why it’s crucial to understand how Benadryl works and when it’s safe to use it for your feline friend.

What Benadryl Can Do for Cats

There are common scenarios that might warrant a cat Benadryl prescription. Here’s a look at when it might be used and what it can help with.

1. Ease Allergic Reactions 

Benadryl is commonly used to alleviate symptoms of allergic reactions in cats.

Cat Benadryl can help reduce itching, swelling, and other allergic symptoms. It acts as an antihistamine, blocking the effects of histamine, a substance your body produces in response to allergens

Types of Cat Allergies

A cat can suffer from various allergies, including environmental allergies triggered by pollen, mold, or dust mites, leading to symptoms like sneezing and itchy skin. 

Food allergies from specific ingredients can cause gastrointestinal issues and skin irritations, while flea allergies can result in severe itching and hair loss from even a single bite.

Contact allergy occurs when a cat’s skin reacts to certain fabrics or chemicals, causing localized itching and redness.

2. Benadryl Cannot Relieve Motion Sickness in Cats

Antihistamines are effective at relieving motion sickness in dogs, but not cats.  

Why Doesn't Benadryl Relieve Motion Sickness in Cats?

Cats don't have histamine receptors in the CRTZ (chemoreceptor trigger zone), so antihistamines don't relieve their variety of motion sickness.

3. Support Anxiety

Some cats are naturally anxious, whether it’s due to separation, loud noises, or new environments. In these cases, cat Benadryl may be suggested as a mild sedative to help calm your pet down.

However, this use is less common and typically considered only when other anxiety management strategies aren’t effective. Other options like CBD oil safe for cats can be a better option.

4. Pre-Surgical Sedation 

In some cases, Benadryl might be used to sedate a cat before a procedure. Its sedative effects can help calm a cat and make handling easier for the vet. However, this should only be done under the strict guidance of your veterinarian, as proper dosing is critical.

Always consult your vet to ensure that cat Benadryl is appropriate for your pet’s specific needs and to determine the correct dosage. Misuse or incorrect dosing can lead to unwanted side effects or complications.

Cats That Should Not Have Diphenhydramine Hydrochloride (Benadryl)

While cat Benadryl (diphenhydramine) can be useful in certain situations, it’s not suitable for every cat. Here’s a quick rundown of the cats that should avoid this medication:

Kittens Less Than 6 Months Old 

Young kittens are more sensitive to medications and may not metabolize diphenhydramine properly, increasing the risk of adverse effects.

Pregnant or Nursing Cats 

The safety of diphenhydramine HCL for pregnant or nursing cats hasn’t been well established, so it’s best to avoid using it unless explicitly recommended by a veterinarian.

A Cat on Certain Medications

If your cat is already taking other medicines, particularly those affecting the central nervous system or those metabolized by the liver, diphenhydramine could interact negatively, leading to increased side effects or reduced efficacy of either medication.

A Cat Allergic to Benadryl 

If your cat has previously shown signs of severe allergic reaction to diphenhydramine, avoid administering this allergy medication in the future.

Cats with Glaucoma

Diphenhydramine can increase intraocular pressure, which is especially dangerous for a cat with glaucoma. This condition is characterized by elevated pressure inside the eye, and using diphenhydramine could worsen it, potentially leading to severe pain or even blindness.

A Cat with Cardiovascular Disease 

If your cat has a history of heart disease or high blood pressure, diphenhydramine is generally not recommended. The medicine can affect heart rate and blood pressure, posing a significant risk to a cat with cardiovascular issues.

A Cat with Hyperthyroidism 

Hyperthyroidism, a common condition in older cats, can cause increased heart rate and metabolism. Diphenhydramine might exacerbate these symptoms, leading to further complications. Always consult your veterinarian before administering this medication if your cat has hyperthyroidism.

Cats with Respiratory Conditions

If your cat has asthma or other respiratory conditions, diphenhydramine could potentially worsen their symptoms. It may cause excessive drying of the mucous membranes or lead to strained breathing, particularly in a cat prone to respiratory distress.

Always consult with your veterinarian before giving your cat any medicine, including diphenhydramine, to ensure it’s safe and appropriate for their specific needs.

Potential Side Effects and Risks of Benadryl

There are potential side effects and risks that you should be aware of when administering this medication to your feline friend.

1. Drowsiness and Sedation

Most cats will experience some level of drowsiness after taking Benadryl. This can be mild, making your cat a bit sleepier than usual, or more pronounced, leading to extended periods of sedation.

2. Excitement

Interestingly, some cats experience the opposite effect, becoming unusually hyperactive or excited. This paradoxical reaction can be startling and might make it seem like the medication is having the opposite of its intended effect.

2. Lethargy

Beyond simple drowsiness, some cats may become lethargic, showing little interest in their usual activities. They might sleep more than usual or seem less responsive.

3. Vomiting and Diarrhea 

Gastrointestinal upset is another potential side effect. If your cat starts vomiting or has diarrhea after taking Benadryl, it’s a sign that the medication might not be agreeing with them.

4. Dry Mouth 

Benadryl can cause dry mouth, which might lead to increased thirst or discomfort while eating. You may notice your cat drinking more water or seeming reluctant to eat.

5. Lack of Appetite 

Some cats may lose interest in food altogether, which can be concerning if it lasts for more than a meal or two.

6. Allergic Reactions 

Although rare, some cats may have severe allergic reactions to Benadryl itself. Signs of an allergic reaction include swelling (especially around the face and paws), hives, difficulty breathing, and sudden collapse. If you notice any of these symptoms, contact your veterinarian or an emergency animal clinic right away.

7. Interactions with Other Medications 

Benadryl can interact with other medicines your cat may be taking, potentially leading to harmful side effects or reducing the effectiveness of the other treatments. Always discuss your cat’s full medical history and current medications with your vet before starting Benadryl dosage.

Correct Cat Benadryl Dosage

Getting the Benadryl dosage right is crucial because what might seem like a minor difference could have significant effects on your pet’s health. Unlike humans, cats are much smaller and have a unique physiology, which means that the amount of Benadryl dosage they can safely take is much lower.

The general rule of thumb for Benadryl dosage (or its active ingredient, Diphenhydramine) is about 1 mg per pound of body weight, given every 8 to 12 hours. For instance, if your cat weighs 10 pounds, a dose of 10 mg is typically considered safe.

However, this isn’t a one-size-fits-all situation—individual cats may have different tolerances, and what works for one might not be appropriate for another.

Cats Benadryl come in various forms, but not all are ideal for cats:

1. Benadryl Tablets & Pills 

Benadryl pills can be tricky to administer to cats on their own. Try hiding the pill in a treat or wet food, ensuring your cat eats the entire dose.

Also keep in mind that most Benadryl pills are not formulated for cats and they might be in 25 mg doses, so be sure to split the dose you have to reflect your cat's weight.

2. Liquid Benadryl

Liquid Benadryl is easier to give felines, especially for cats that refuse pills.

Children's Benadryl liquid can be dosed more precisely, making it easier to administer to cats weighing less than 12.5 pounds. Use a syringe to administer directly into the cat’s mouth.

Make sure that the liquid you're using is free from sodium and flavoring agents.

Is Your Cat Foaming at The Mouth After Liquid Benadryl?

If this happened, it's likely because the product you used had sweeteners made for humans. You don't have to worry unless the foam accompanied by other symptoms, or if it persists.

Interestingly, cats can foam at the mouth when they don't enjoy the taste of something. This foam is simply increased saliva production mixed with the air, and it's a method for your cat to quickly eliminate the bad taste. 

3. Benadryl Chewables

Some cats may prefer chewables, but make sure the dosage is correct and that there are no harmful additional ingredients.

Even though Benadryl is available over the counter and is generally safe when used correctly, it’s vital to consult your veterinarian to determine how much Benadryl you can use to treat symptoms in your cat.

Your vet will take into account your cat’s overall health, any existing conditions, and other medications they may be on to ensure that Benadryl dosage is both safe and effective.

Benadryl Overdose in Cats

While Benadryl can be useful in managing allergy symptoms and anxiety in cats, it’s not without risks. Overdosing on Benadryl can be dangerous, even life-threatening.

Symptoms of a Benadryl overdose in cats include extreme lethargy, difficulty breathing, coma, seizures, dry mouth, or even respiratory depression, seizure, and loss of consciousness.

That’s why it’s critical to consult with your veterinarian before giving your cat any medication and to know how much Benadryl to give your pet. They can provide the correct Benadryl dosage and ensure it’s appropriate for your cat’s specific health needs, so you can help your feline friend feel better without any unnecessary risks. 

If you suspect your cat has been given too much Benadryl, visit your vet immediately.

Natural Alternatives to Benadryl

Natural alternatives can be gentle and effective options for managing your cat’s allergies or discomfort. However, it’s essential to use these remedies thoughtfully and consult with your veterinarian to ensure they fit your cat’s specific needs and complement their overall care plan.

1. CBD Oil for Calming & Allergies

CBD oil has been gaining popularity as a natural remedy for various conditions, including anxiety and inflammation. CBD is a chemical found in the hemp plant but it does not contain the psychoactive compound that produces a high. It interacts with your cat’s endocannabinoid system to promote relaxation and reduce discomfort. 

Learn more about CBD oil for cats here.

2. Fish Oil for Cat Skin Allergies

Rich in omega-3 fatty acids, fish oil can help reduce inflammation and support overall skin and coat health. This can be particularly useful for cats suffering from itchy skin and to treat allergies. Fish oil can be added to your cat’s diet in the form of a supplement or mixed with their food

3. Vitamin E

Vitamin E is known for its antioxidant properties and can help support healthy skin, shiny coat and treat allergies. It can aid in soothing irritated skin caused by allergies or environmental factors.

4. Oatmeal Shampoos

Shampoos containing oatmeal are excellent for soothing itchy, inflamed skin. Oatmeal acts as a natural anti-inflammatory and helps to moisturize the skin, reducing dryness and irritation.

5. Fatty Acids

Supplements rich in fatty acids, such as those containing omega-6 or omega-3, can improve skin condition and coat quality relieving symptoms of allergic skin disease. They also help manage inflammation and support overall health.

Final Thoughts on Benadryl for Cats

Benadryl can be a helpful medication for both cats and humans when used correctly to manage allergies and ease motion sickness. However, it's crucial to avoid self-medicating with over-the-counter drugs without veterinary guidance. Cats have unique health needs and sensitivities, so the risk of adverse effects is significant when using human medications.

Always consult your veterinarian before administering any medication, including Benadryl, to ensure it's safe and appropriate for your cat's specific situation. It's important for pet parents to monitor their cats closely and have frequent vet visit programs.

Work closely with your vet, so you can ensure your feline friend receives the best care possible and stays happy and healthy.

References

1. Sicari V, Zabbo CP. Diphenhydramine. [Updated 2023 Jul 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526010/

2. National Center for Biotechnology Information (2024). PubChem Compound Summary for CID 3100, Diphenhydramine. Retrieved August 21, 2024 from https://pubchem.ncbi.nlm.nih.gov/compound/Diphenhydramine.

3. Takov V, Tadi P. Motion Sickness. [Updated 2023 July 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539706/

4. Crivineanu, M., Dobre, I. R., Rotaru, E., & Păunescu, I. (2017). The effect of antihistamines on allergic inflammation and anxiety in dogs and cats.