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One selection filters the source overview, clinical facts, reports and dose calculator. Literature references are not species-filtered.
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Source overview
Recorded excerpts for one species. Each dose remains a separate source entry; no regimen is selected.
Choose one species to view its source overview. All-species evidence remains available below.
View full clinical evidence and sources ↓Clinical evidence
Pending clinical review (PROPOSED)Rule-based (RULE_BASED)— applies to the facts and dose entries in this species selection; individual source records retain their own status.
Indications2
Pruritus (adjunct), motion sickness, mild allergic reaction/anaphylaxis adjunct, pre-transfusion/pre-chemo prophylaxis
DogCatExtra-label (EXTRA_LABEL)2 source records · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Original excerpt: Pruritus (adjunct), motion sickness, mild allergic reaction/anaphylaxis adjunct, pre-transfusion/pre-chemo prophylaxis — Extra-label
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Original excerpt: Pruritus (adjunct), motion sickness, mild allergic reaction/anaphylaxis adjunct, pre-transfusion/pre-chemo prophylaxis — Extra-label
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Dose regimens3
This calculator performs arithmetic only on the sourced dosing field shown for each result — it does not verify the field's accuracy, does not select which field to use for a patient, and does not replace a veterinarian's order. Not for clinical use. Confirm every result against the primary source before dispensing.
Choose one species above to view its dose calculator.
Adverse effects204
Sedation, dry mouth (anticholinergic) — Most common
DogCatNot applicable (NOT_APPLICABLE)2 source records · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Paradoxical excitement — Documented
CatNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
GI effects (vomiting, diarrhea, anorexia) — Less common
Other speciesNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Other species · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
These are counts of spontaneously reported events, not proven adverse effects, causal relationships, or incidence rates.
Bars compare report counts within each species; they do not show incidence.
More reportsFewer reportsDog
- Vomiting1,341 reports
- Lethargy (see also Central nervous system depression in 'Neurological')834 reports
- Diarrhoea605 reports
- Emesis421 reports
- Anaphylaxis414 reports
- Facial swelling (see also 'Skin')364 reports
- Hives (see also 'Skin')319 reports
- Lack of efficacy - NOS298 reports
- Anorexia292 reports
- Other abnormal test result NOS282 reports
- Pale mucous membrane280 reports
- Panting280 reports
Cat
- Vomiting109 reports
- Lethargy (see also Central nervous system depression in 'Neurological')67 reports
- Fever51 reports
- Anaphylaxis49 reports
- Lethargy (see also Central nervous system depression in Neurological)45 reports
- Death44 reports
- Not eating44 reports
- Anorexia41 reports
- Death by euthanasia40 reports
- Diarrhoea35 reports
- Emesis (multiple)35 reports
- Other abnormal test result NOS35 reports
Monitoring1
Clinical efficacy, sedation level
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Monitoring Parameters · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Contraindications1
Hypersensitivity to antihistamines in this class
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Contraindications & Warnings table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Precautions4
Angle-closure glaucoma, prostatic hypertrophy, bladder-neck/pyloroduodenal obstruction, COPD (if mucus is a problem), hyperthyroidism, cardiovascular disease/hypertension
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Contraindications & Warnings table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Not the best antiemetic choice for cats — histamine is not a major mediator of feline emesis; prefer maropitant or a phenothiazine for that indication in cats.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Clinical pearl · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Efficacy for pruritus control alone (without other therapy) is modest at best — set expectations as adjunctive, not primary, therapy.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Clinical pearl · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Distasteful liquid form — use tablets/capsules where possible for compliance.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Clinical pearl · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Interactions2
Other CNS depressants — Additive sedation
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Drug Interactions table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Anticholinergic drugs (incl. TCAs) — Potentiate anticholinergic effects
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Drug Interactions table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Pharmacokinetics6
Bioavailability — 40–60% (human, high first-pass)
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Protein binding — ~80% (human)
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Half-life — 2.4–9.3h (human)
DogCatNot applicable (NOT_APPLICABLE)2 source records · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Metabolism — Hepatic
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Elimination — Urine (metabolites)
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Pregnancy / lactation considerations1
Human FDA category B. Papich canine/feline class B. Distributed into milk — caution, especially in neonates.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 419–421; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 251–253 — Pregnancy & Lactation · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Literature references17
References are linked to this drug. Species applicability is not recorded here, so the species filter does not narrow this list. Imported dates do not retain their original precision; confirm dates in the original citation.
- Loss of Tolerance in Long-Term Allergen Immunotherapy: A Case of Late-Onset Systemic Anaphylaxis.
Study summary not available in the imported record. Open the original citation to review the study.
- Epidural diphenhydramine in sheep: an exploratory study of sensory-selective blockade and motor-sparing effects.
Study summary not available in the imported record. Open the original citation to review the study.
- Antinociceptive and motor-blocking effects of epidurally administered diphenhydramine at different concentrations in conscious rabbits: a randomized-controlled trial.
Study summary not available in the imported record. Open the original citation to review the study.
- Assessment of an integrated therapeutic protocol for sheep with acute ruminal impaction: diagnostic and prognostic significance of rumen functions and hepatorenal biomarkers.
Study summary not available in the imported record. Open the original citation to review the study.
- Antemortem diagnostic tests and treatment outcomes using ivermectin in 13 cases of presumptive feline neurocuterebriasis.
Study summary not available in the imported record. Open the original citation to review the study.
Sources: PubMed, National Library of Medicine; openFDA, U.S. Food and Drug Administration; Plumb DC. Plumb's Veterinary Drug Handbook. 7th ed. PharmaVet Inc; 2011.
Owner information handout
Plain-language medication information to review with the owner. Open the handout to print it or download a PDF.