Meds A-Z
Diphenhydramine Hcl
Detailed information about Diphenhydramine Hcl
Pet Owner Quick Guide
Start here: what this medicine is for, what it does, and when it's usually needed.
Usually used for:
Use this medication only when your veterinarian confirms it matches your pet's condition.
What it does:
Use this medication only when your veterinarian confirms it matches your pet's condition.
When it's needed:
Use this medication only when your veterinarian confirms it matches your pet's condition.
Commonly reported reactions:
- (2 reports)
- (1 reports)
- (1 reports)
What to ask your vet today:
- Is this medicine the right fit for my pet’s current symptoms?
- Which warning signs mean I should call back right away?
- How should I handle missed doses or refusal to take the medicine?
Diphenhydramine Hcl
Drug type: Generic ingredient • Generic profile • No FDA branded products linked
Species: Both
Manufacturer: MSK
Quick Facts
Official label facts first, then secondary summaries. Marketing content is separated below.
No source yet.
Warnings / Contraindications
No contraindication summary is linked yet.
No owner-focused warning rows are linked yet.
Adverse Reactions
Snapshot first, detailed rows second. This section summarizes signal data and is not a diagnosis.
Tap or hover a reaction to see what it means in plain language.
Most Reported Reactions
| Reaction | Cases | Species | Serious cases |
|---|---|---|---|
| 2 | Cat, Dog | 2 | |
| 1 | Dog | 1 | |
| 1 | Dog | 1 | |
| 1 | Dog | 1 | |
| 1 | Cat | 1 | |
| 1 | Cat | 1 | |
| 1 | Dog | 1 | |
| 1 | Cat | 1 |
Species coverage: Cat (18) Dog (14)
View detailed reaction table
| Reaction | Species | Seriousness | Frequency | Reports |
|---|---|---|---|---|
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Non-serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Cat | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Dog | Serious | - | 1 | |
| Dog | Serious | - | 1 |
- https://api.fda.gov/animalandveterinary/event.json · adverse_reaction · openFDA case USA-USFDACVM-2021-US-052475
Storage & Handling
No storage/handling guidance is linked yet.
Documents
Official label facts are separated from secondary summaries.
No linked label PDFs or safety notices yet.
No source yet.
No source yet.
Promotional Materials (Marketing)
This content is marketing material and not clinical guidance.
No marketing assets are linked yet.
No source yet.
Technical appendix (vet reference)
Canonical medication sections are above. This legacy block remains available for deeper cross-reference without cluttering the primary workflow.
At a Glance
Quick facts and links to official labeling and safety signals.
- Medication catalog: Source PetWisePlus | Refreshed Feb 12, 2026, 10:44 PM UTC
-
Animal Drug Product Listing Directory (NDC):
Source FDA
| Refreshed Feb 16, 2026, 11:00 AM UTC
Package/product NDCs from FDA’s electronic listing directory (XLS).
- openFDA reaction terms: Source FDA openFDA | Refreshed Feb 9, 2026, 3:14 AM UTC
- openFDA case summaries: Source FDA openFDA | Refreshed Feb 9, 2026, 3:21 AM UTC
Diagnosis-code mappings are not available for this medication yet.
Counseling and Monitoring Highlights
Global Pet owner/Vet mode is controlled in the header. This section avoids duplicate in-page persona tabs.
Data Sources & Revision History
Every non-trivial field is expected to include provenance and update timestamps.
- side_effects: Top reported reactions (openFDA): Vomiting, Lethargy (see also Central nervous system depression in 'Neurological'), Facial swelling (see also 'Skin'), Hives (… (Official, 2026-02-12)
- side_effects updated 2026-02-12 22:44 by etl_backfill • Backfilled from existing medication fields
FDA Products & Applications (Animal Drugs @ FDA)
No linked FDA product applications are available for this ingredient yet.
Usage
No approved usage text is linked yet for this ingredient.
- Catalog species: Both
- Safety reports available: 10 openFDA case summaries (view)
Contraindications
No approved contraindication text is linked yet. Review FDA label highlights and openFDA safety reports before making treatment decisions.
Side Effects
No approved side-effect narrative is linked yet.
openFDA reaction signals are available for Dog 8 and Cat 8 (view top reported reactions).
Top Reported Reactions (openFDA)
Aggregated reaction terms from FDA openFDA reports (not verified; does not prove causation).
Data source: FDA openFDA Animal & Veterinary adverse event reports.
Adverse Event Case Summaries (openFDA)
These are individual FDA adverse event reports. They are unverified and do not prove the medication caused the reaction.
Dog, Terrier - Yorkshire, Female, 11 year, 2.57 kilogram • Drug: MSK, Unknown • Reactions: Tiredness (lethargy), Not eating, Diarrhea, Constipation, Jaundice… • Outcome: Euthanized
- Report ID: USA-USFDACVM-2024-US-050996
- Serious AE: Yes
- Treated For AE: No
- Sex: Female
- Age: 11.00 Year
- Weight: 2.570 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
Dog, Terrier - Yorkshire, Female, 10 year, 4.6 kilogram • Drug: MSK, Unknown • Reactions: Cough, Anxiety • Outcome: Ongoing
- Report ID: USA-USFDACVM-2024-US-029316
- Serious AE: No
- Treated For AE: Yes
- Sex: Female
- Age: 10.00 Year
- Weight: 4.600 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
Dog, Pit Bull, Female, 6.5 year, 43 kilogram • Drug: MSK, Injection, Intramuscular, Dose: 1 dose per animal, Frequency: 1 per day • Reactions: Death by euthanasia, Lateral recumbency, Injection site bruising, Injection site swelling, Injection site serosanguinous discharge… • Outcome: Euthanized
- Report ID: USA-USFDACVM-2023-US-014852
- Serious AE: Yes
- Treated For AE: Yes
- Sex: Female
- Age: 6.50 Year
- Weight: 43.000 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Intramuscular
- Form: Injection
- Dose: 1 dose per animal
- Frequency: 1 per day
Dog, Maltese, Female, 5 year, 4.218 kilogram • Drug: MSK, Solution, Intramuscular • Reactions: Tiredness (lethargy), Other abnormal test result NOS, Anaemia NOS, Immune mediated haemolytic anaemia, Active urine sediment • Outcome: Ongoing
- Report ID: USA-USFDACVM-2022-US-060159
- Serious AE: Yes
- Treated For AE: Yes
- Sex: Female
- Age: 5.00 Year
- Weight: 4.218 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Intramuscular
- Form: Solution
Dog, Crossbred Canine/dog, Male, 10 year, 31.751 kilogram • Drug: MSK, Injection, solution, Intravenous, Dose: 1.75 mL per animal • Reactions: Anaemia NOS, Weight loss, Icterus, Saline slide agglutination test, positive, Immune mediated haemolytic anaemia… • Outcome: Ongoing
- Report ID: USA-USFDACVM-2022-US-035613
- Serious AE: Yes
- Treated For AE: Yes
- Sex: Male
- Age: 10.00 Year
- Weight: 31.751 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Intravenous
- Form: Injection, solution
- Dose: 1.75 mL per animal
Cat, Domestic Shorthair, Female, 19 month, 4.468 kilogram • Drug: MSK, Unassigned, Unknown • Reactions: Vomiting, Fever, Diarrhea • Outcome: Ongoing
- Report ID: USA-USFDACVM-2021-US-057884
- Serious AE: Yes
- Treated For AE: Yes
- Sex: Female
- Age: 19.00 Month
- Weight: 4.468 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
- Form: Unassigned
Cat, Domestic Shorthair, Male, 3 year • Drug: MSK, Injection, solution, Unknown • Reactions: Anaphylaxis, Bloody diarrhoea, Vomiting, Fever, Tachycardia… • Outcome: Recovered/Normal
- Report ID: USA-USFDACVM-2021-US-057809
- Serious AE: Yes
- Treated For AE: Yes
- Sex: Male
- Age: 3.00 Year
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
- Form: Injection, solution
Cat, Domestic Shorthair, Female, 13.5 year, 5.67 kilogram • Drug: MSK, Liquid, Unknown • Reactions: Vomiting, Blood in vomit, Weight loss, Loss of appetite, Elevated total bilirubin… • Outcome: Died
- Report ID: USA-USFDACVM-2021-US-055950
- Serious AE: Yes
- Treated For AE: Yes
- Sex: Female
- Age: 13.50 Year
- Weight: 5.670 Kilogram
- Case-reported brand: MSK
- Case-reported manufacturer: MSK
- Route: Unknown
- Form: Liquid
Data source: FDA openFDA Animal & Veterinary adverse event reports.
Overdose Information
No approved overdose-management text is linked yet. If overdose is suspected, contact a veterinarian or emergency clinic immediately.
Storage & Handling
No approved storage guidance is linked yet for this ingredient. Use manufacturer packaging and veterinary guidance for handling/storage.
Share Your Thoughts
Let others know your experience or advice regarding this medication.
This medication has not been reviewed by a veterinarian yet.