Diphenhydramine
“This page provides important general information for pet owners whose animals have been prescribed Diphenhydramine in Perth during a consultation by Dr Noor.”
Key Information on Diphenhydramine
- This medicine is an allergy medicine used for allergy-related problems.
- It is also used to help prevent travel-related nausea (motion sickness) or vomiting.
- Diphenhydramine comes in many different products, including products mixed with other ingredients.
- Use only the exact product your veterinarian recommends.
- You can give this medicine with food or on an empty stomach.
- If you are giving it to help with motion sickness, give it 30 to 60 minutes before the trip.
- The side effects seen most often are sleepiness and low energy.
- These effects may lessen after your pet has been on the medicine for a while.
Note: This handout is meant to address common questions. It does not include every detail about this medicine and does not replace guidance from your veterinary healthcare team.
Description
- Allergy medicine.
- Comes as tablets, chewable tablets, capsules, and liquid taken by mouth.
- There are many diphenhydramine products and products combined with other ingredients.
- Use only the product your veterinarian recommends.
Other common names
- Banophen
- Benadryl
- Diphenhist
- Vetadryl
Uses
This medicine is not specifically approved for animals, but it is approved for people. Your veterinarian may still choose to use it in animals (this is called extra-label use), including for:
- Helping treat or prevent itching caused by allergies in dogs, cats, and other animals.
- Helping treat allergic reactions in dogs, cats, and other animals.
- Helping prevent allergic reactions before vaccinations in dogs and cats.
- Helping prevent motion sickness and vomiting in dogs and cats.
- Helping treat mast cell tumors when used together with other treatments in dogs and cats.
Veterinary-labeled diphenhydramine products list different uses for dogs and cats, but these products are not approved.
Before this medication is given
No medicine is completely safe for every animal. Talk with your veterinarian about:
- Any other medicines or supplements your animal is taking.
- Any health problems your animal has now, or has had in the past.
- Any unwanted reactions your animal has had to medicines before.
- The possible risks of using this medicine if your animal is pregnant or nursing.
Also tell your veterinarian if your animal is going to have allergy testing.
Warnings for animals
Do not use in animals:
- Animals that have an allergy to this medicine.
Use with caution in animals:
- Animals with heart disease.
- Animals with seizure disorders.
- Animals with glaucoma.
- Animals with an enlarged prostate.
- Animals with a blockage in the stomach/intestines or in the urinary tract.
- Animals with breathing disease, such as asthma.
- Animals with high blood pressure (hypertension).
- Animals with high thyroid levels (hyperthyroidism).
Some animal competitions do not allow certain medicines. If your animal competes, check the rules while your animal is taking this medicine.
Warnings for humans
After you handle any medicine, wash your hands.
How do I give this medication?
Give this medicine exactly the way your veterinarian prescribed it. Always follow the directions on the prescription label.
- Give with food or without food.
- If you are giving a liquid, measure it with an oral syringe, a medicine cup, or a dosing spoon.
- Do not measure with kitchen spoons.
- This medicine may cause a dry mouth.
- Make sure your animal always has plenty of fresh water available.
- If you are giving this medicine to help prevent motion sickness, give it 30 to 60 minutes before traveling.
- Be careful if your animal is a working animal or service animal.
- This medicine may make them too sleepy to do their job.
Side effects
Common — contact your veterinarian if any of these signs are strong, keep happening, or get worse over time:
- Dry mouth.
- Sleepiness and low energy.
- This may lessen the longer your animal takes this medicine.
Less common — contact your veterinarian if any of these signs are strong, keep happening, or get worse over time:
- Some animals may become more excited or overly active instead of sleepy, especially cats.
- Vomiting or diarrhea.
- Eating less than usual.
Severe — stop the medication and contact your veterinarian immediately if you notice any of these signs:
- Extreme sleepiness.
- Constipation or trouble urinating.
- Redness of the eyes or fluid coming from the eyes.
- Restlessness or unusual behavior changes.
How will I know it's working?
When this medicine is used for allergies or motion sickness, it starts to work within 1 to 2 hours. After that, you should notice your animal’s signs improving.
Call your veterinary clinic if your animal’s signs get worse or do not get better.
How long will the medication effects last?
The medicine’s effects will be gone within 24 hours after the last dose.
How long do I give it for?
The length of treatment can vary. Give it for the amount of time your veterinarian instructs. A refill may be needed.
Overdose
Possible overdose signs include very strong sleepiness, shaking, or poor coordination. If you see or think an overdose may have happened, contact your veterinarian or an animal poison control center right away (a consultation fee applies):
- Pet Poison Helpline: (855) 764-7661
If possible, have the product container or label with you.
Missed dose
In most situations, if you forget a dose:
- Give the dose as soon as you remember, and then go back to the usual schedule.
If it is almost time for the next dose:
- Do not give the missed dose.
- Give the next dose at the regular time.
- Continue with the normal schedule.
If you are not sure what to do, call your veterinary clinic. Do not give two doses at once and do not give extra doses.
Storage
- Keep the medicine in its original container at room temperature.
- Keep it away from light.
- Store it where children and animals cannot reach it.
- Flavored versions may taste good to animals.
- Store them securely and well out of reach to help prevent accidental overdose.
Disposal
Do not flush this medicine down the toilet and do not pour it into a sink. Ways to get rid of unused or expired medicine include:
- Drug take-back locations:
- This is the best option when available.
- To find a nearby location, contact local law enforcement or your waste management office.
- Home disposal:
- Mix the medicine with coffee grounds or kitty litter, place it in a sealed plastic bag, and put it in the trash.
Do not keep leftover medicine for later use and do not give it to anyone else to use.
Questions?
Speak with your veterinarian.
“Disclaimer: The information on this page is provided as general educational material only. Every animal’s health situation is unique, and treatment decisions must be based on a full veterinary assessment. Always follow the specific instructions given during your consultation, and contact the prescribing veterinarian if you have any concerns.”