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Diphenhydramine (Generic Benadryl)

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Product Info
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Customer Reviews
Product Info
What is Diphenhydramine (Generic Benadryl)?

Diphenhydramine is an antihistamine used to relieve allergy symptoms, insect stings, motion sickness, travel anxiety, and other conditions.


Cats and Dogs

  • Effectively relieves allergy symptoms and itching caused by insect bites
  • Can be used as a sedative to treat motion sickness or travel anxiety
  • Relieves coughing
How it Works:

Diphenhydramine comes in 25mg minitabs or 50mg capsules, and is a generic version of Benadryl. As an antihistamine, it counteracts the effect of histamine, which causes symptoms like itching and sneezing.


This medication should not be used in pregnant or nursing animals. Do not use the diphenhydramine available in combination with sinus or cold medicines in your pet.

Brand Name:

Benadryl (Warner Lambert), Histacalm (Virbac)

Generic Name:

Diphenhydramine (dye-fen-hy'-dra-meen)



What is this medication used for:

Diphenhydramine is an antihistamine used to relieve allergy symptoms, insect bites or stings and other causes of itching. It is also used for its sedative and antiemetic effects in the treatment of motion sickness and travel anxiety. It is also used for its antitussive effect.


Diphenhydramine is a non-prescription (OTC) product available as 25mg tablets and 50mg capsules.

How this medicine should be used:

Oral diphenhydramine is not FDA-approved for use in veterinary medicine; however, it is a commonly accepted practice to use this medication in dogs and cats. The usual dose in dogs and cats is 0.5-2mg/pound every 8-12 hours. The slow release capsule should not be mixed or dissolved in food. Do not give sinus or cold medicines containing diphenhydramine to your pet.

What are the side effects:

Side effects of diphenhydramine include drowsiness, dry mouth and urinary retention. Rarely, vomiting and diarrhea can occur.

What special precautions are there:

Do not use this medication in animals that are allergic to it or other antihistamines. Do not use in animals with glaucoma, prostate disease, urinary obstruction, and high blood pressure. Do not use in pregnant or nursing animals. Use with caution when given with other CNS (central nervous system)-depressant drugs such as tranquilizers or barbiturates. Always tell your veterinarian and pharmacist what other medications your pet is taking.

In the event of an overdose:

Contact your veterinarian or veterinary emergency room. Symptoms of overdose can include seizures, extreme drowsiness, coma, respiratory depression, and death.

How should I store this medication:

Keep this medication in the container it came in, tightly closed. Store this medication at room temperature, away from excess heat, light, and moisture. Do not store in the bathroom. Throw away any medication that is outdated or no longer needed. Keep medication away from children and pets.

How to Use
  • Diphenhydramine is an antihistamine used to relieve allergy symptoms, insect stings, motion sickness, travel anxiety and other conditions.
  • It is available over-the-counter (OTC) as 25mg tablets and 50mg capsules.
  • Diphenhydramine should not be used in dogs or cats that are pregnant or nursing.

The slow release capsule should NOT be mixed or dissolved in food. Do not use sinus or cold medications containing diphenhydramine in your pet.

All weights
Give 0.5 - 2mg per lb of pets body weight every 8 -12 hours
Do not use!

Store this medication at room temperature, away from excess heat, light and moisture.

Active Ingredients (per Minitab)
Diphenhydramine HCl 25 mg Minitab
Diphenhydramine 25 mg
Other Ingredients (per capsule): Corn starch, D&C red #27, Dicalcium Phosphate, Magnesium Stearate, Microcrystalline Cellulose, Polyethylene Glycol, Polyvinyl Alcohol, Silicon Dioxide, Stearic Acid, Talc, Titanium Dioxide.
Active Ingredients (per Minitab)
Diphenhydramine 50 mg Capsules
Diphenhydramine Hydrochloride 50 mg
Other Ingredients (per capsule): Colloidal Silicon Dioxide, Croscarmellose Sodium, D&C Red #28, FD&C Blue #1, FD&C Red #3, FD&C Red #40, Gelatin, Lactose, Magnesium Stearate. May also contain Polysorbate 80 and iron oxide.
Customer Reviews
Diphenhydramine (Generic Benadryl) is rated 4.0181818181818185 out of 5 by 55.
Rated 1 out of 5 by from Not only sneezing, but now drooling! The product help Annabelle with a seasonal allergy/cold, but getting it down, forget it! Why can these be gel caps that can be syringed and shot in the back of her mouth. Because of her size I can't giver her the entire pill, so has to be crumbled in laxitone which never helps! The taste is apparently so bad she salivates and spits out whats left for 20 minutes!! What a mess and then she won't eat for a day b/c the taste is still in her mouth!
Date published: 2016-08-24
Rated 4 out of 5 by from It does the job. This product does seem to help relieve the allergy problems my dog was having and it does calm him down and makes him a little sleepy. I don't like the capsules though, I have to open them and put the powder in a spoon with a little water to give them to him, he is wise to all the other tricks. All in all, I would purchased this product again.
Date published: 2015-06-10
Rated 3 out of 5 by from This medication is not helpful in my dog's itching, so I have found big relief in Piriton and Zyrtec.
Date published: 2015-03-04
Rated 5 out of 5 by from For cats, place it far back in throat Giving Benadryl to my dogs has always been easy---just hide it in a spoon of peanut butter, and it's gone down the hatch, easy peasy. But cats don't believe in gulping down a glob of peanut butter, and Benadryl apparently tastes pretty horrendous to a cat. After some trial and error, I have deduced that it is taste-induced nausea which leads to vomiting (and of course the foaming). So I experienced the same thing as many of the other cat owners here when giving Benadryl---the result is lots of foaming and vomiting. I switched to Zyrtec, since it doesn't seem to taste as bad to a cat, but after Zyrtec failed to help with her symptoms, and by this time having had lots of practice pilling my cat, I decided to give Benadryl another try. I have found that I CAN dose my cat with Benadryl without making her sick. The trick is to place the pill far back in the throat. With the cat's head back and the mouth open, drop the pill in---aiming for the back of the throat---while trying to avoid the tongue altogether. If it lands on the tongue (even the back part) rather than in the throat, quickly push the pill back with a finger. Getting it as far back as possible without ever hitting the tongue keeps the cat from being able to eject the pill back up into the mouth, and thus never tastes the pill. Now that I am preventing her from tasting the Benadryl, there has been no more vomiting, no more foaming, and best of all, no more chewiing off her fur and sneezing fits (at least so far).
Date published: 2015-01-04
Rated 5 out of 5 by from very effective Buster takes one 50mg pill before bed. His sleep cycle had been disturbed but he now sleeps his regular hours and is more active when he wakes up. If I notice his breathing during the day indicates some congestion when the wind is blowing dust and pollen around, one pill relieves it within 30 minutes. His vet has examined him and agrees he has occasional allergies and diphenhydramine is the perfect solution.
Date published: 2014-12-23
Rated 3 out of 5 by from Not as Effective As I Thought! When I purchased this product, I was hoping for it to be a little more effective. It really hasn't helped with his constant itching, but it stopped my dog from constantly biting on his paws. It does somewhat have a calming effect on him though, and I find that they help him sleep.
Date published: 2014-11-14
Rated 4 out of 5 by from We started to give Lily the pills about two weeks ago and she is much better now. She was constantly sneezing. Now it is only occasionally. Appeared to work. Didn't do anything for her itching and scratching. Will work on that one
Date published: 2014-11-05
Rated 2 out of 5 by from Disappointed with effectiveness My lab mix has terrible skin allergies and her vet suggested giving her generic Benadryl. It worked marginally for awhile and then it eventually didn't seem to help. I was hoping this product was stronger or different from Benadryl, but it is not. It has exactly the same ingredients and dosage as the Benadryl. It was a waste of my money.
Date published: 2014-09-27
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My Jack Russell mix is about 15-16 yrs old and weighs approx. 15lbs. What is the correct dose for her? We use to give her liquid Benadryl, but I don't see it here in this store. Her Doctor was telling us to give her 5ml twice daily as needed.

Asked by: Princess
Typical doses are 0.5 - 2 mg per lb of pets body weight every 8 -12 hours. For your 15 lb Jack Russel Mix, this would be about 7.7-30 mg every 8-12 hours. One of the 25 mg tabs falls into this range, and can be given 2-3 times daily as needed.
Answered by: Christine
Date published: 2016-10-14

how long has this drug been in use and how was it developed?

Asked by: Lovely
Diphenhydramine is the generic of Benadryl. It has been around for decades and is very commonly used in both humans and pets for allergies and rash. Diphenhydramine was discovered by George Rieveschl, in 1943 at the University of Cincinnati. He was investigating potential muscle-relaxant drugs by screening several compounds that his team had synthesized, one of which was diphenhydramine (beta dimethyl-aminoethyl benzhydryl ether). He discovered that diphenhydramine was not only a potent muscle-relaxant, but also had a potent anti-histamine effect.
Answered by: Christine
Date published: 2016-10-11

Is it safe to give banophen 25mg safe for dogs? 

Asked by: Cownie
Yes, Banophen (diphenhydramine) is safe for dogs. The dose is based on weight, as follows: give 0.5-2mg per lb of pets body weight every 8 -12 hours.
Answered by: Christine
Date published: 2016-10-11

My Maltese is very smart. If I give him a pill in a pill pocket or cheese or whatever he knows it and will not touch it. It's impossible to get a pill down his throat. He bites his feet and scratches all the time. Any suggestions? 

Asked by: Pat44
You can crush diphenhydramine and try putting it in his food if this will help.
Answered by: Christine
Date published: 2016-10-04

Can it be used on cats

Asked by: Sue27
Yes! Diphenhydramine can absolutely be used in cats. The typical dosing is 2-4 mg/kg (0.9-1.8 mg/lb) 2-3 times a day.
Answered by: Christine
Date published: 2016-09-28

Does this make the dogs lethargic or sleepy?  I would like to try this for my dog who scratches constantly and we've not been able to determine the allergy causing it. But I don't want her to end up groggy and sleeping all day.

Asked by: Mozek
Although the sedative effects may diminish over time, lethargy is one of the most common side effects of diphenhydramine.
Answered by: paulpharmacistintern
Date published: 2016-08-06

How much Benadryl should I give my cat, she is only 7 pounds, very tiny.  Was going to give it before bed since it will probably cause her to be sleepy 

Asked by: kitty21
An estimate would be a 5-10mg dose, however consult your veterinarian for a more specific dose for you cat.
Answered by: paulpharmacistintern
Date published: 2016-08-06

Can I give my adult cat a 1/4 of a Benedryl pill if she's sneezing and has a stuffy nose

Asked by: Carri
Hi there, you can give 0.5 - 2mg per lb of pets body weight every 8 -12 hours
Answered by: James PetMeds Pro
Date published: 2016-07-20
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