Pseudoephedrine
Pseudoephedrine hydrochloride
Also known as: Equiphed · Sudafed · Equi-Phar Equi-Hist 1200 Granules · Drixoral · Histgranules · Tri-Hist · Kid Kare · pseudoephedrini · pseudoephedrina
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| For urinary incontinence, or as a decongestant | 0.2-0.4 mg/kg [or practically, 15-60 mg (total dose) per dog] | PO | q8-12h | — | 🌎 NA |
| To increase urethral tone | 1.5 mg/kg | PO | two to three times a day | — | 🌎 NA |
| For retrograde ejaculation | 4-5 mg/kg | PO | three times daily or 1 to 3 hours before semen collection or attempted breeding may be tried. | — | 🌎 NA |
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| As a decongestant | 1 mg/kg | PO | q8h | — | 🌎 NA |
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| For use when an antihistamine/decongestant may be useful using the pyrilamine/pseudoephedrine oral granules | ½ ounce (1 tablespoonful) per 1,000 lb body weight. May mix with feed and repeated at 12 our intervals if needed. | PO | q12h | — | 🌎 NA |
- For use when an antihistamine/decongestant may be useful using the pyrilamine/pseudoephedrine oral granules: Do not use at least 72 hours before sporting events. ARCI UCGFS CLASS 3 DRUG.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Pseudoephedrine is an oral sympathomimetic amine. In veterinary medicine, it is primarily utilized as a second-line agent for urethral sphincter mechanism incompetence (USMI) in dogs when phenylpropanolamine (PPA) is unavailable or contraindicated. It also serves as a nasal decongestant and a treatment for retrograde ejaculation.
Clinical Pearl: Pseudoephedrine is generally considered less efficacious and more prone to causing adverse effects (like agitation and hypertension) compared to PPA for urinary incontinence.
Due to its status as a precursor for illicit methamphetamine synthesis, its sale is heavily restricted in many regions (e.g., Combat Methamphetamine Epidemic Act in the US), making procurement challenging.
Mechanism of action
Pseudoephedrine acts as an indirect-acting sympathomimetic.
- Enters sympathetic nerve terminals → stimulates the release of endogenous norepinephrine from storage vesicles.
- Norepinephrine binds to alpha-1 adrenergic receptors in the smooth muscle of the urethra and blood vessels → vasoconstriction and increased urethral sphincter tone (preventing urine leakage).
- Also weakly stimulates beta-adrenergic receptors → positive chronotropic effects (increased heart rate) and mild bronchodilation.
Safety & warnings
Contraindications
- Glaucoma
- Prostatic hypertrophy
- Hyperthyroidism
- Diabetes mellitus
- Cardiovascular disorders
- Hypertension
Adverse effects
- Panting
- Decreased appetite
- Lethargy
- Tachycardia
- CNS excitement
- Restlessness
- Insomnia
- Hypertension
- Arrhythmias
Precautions
Use with caution in patients with glaucoma, prostatic hypertrophy, hyperthyroidism, diabetes mellitus, cardiovascular disorders, or hypertension. Restricted drug in USA; can be used as a precursor to manufacture methamphetamine. Safe use has not been established during pregnancy (FDA Category C in humans). Not recommended during breastfeeding as the drug enters maternal milk.
Drug interactions
Should not be given within two weeks of receiving MAOIs; risk of severe hypertension and toxicity.
Increased chance of hypertension if given concomitantly.
Increased toxicity may result; should not be administered together.
Increased chance of hypertension if given concomitantly.
Monitoring
- Efficacy (improvement in incontinence or congestion)
- Heart rate
- CNS stimulation (restlessness, agitation)
- Appetite
Pharmacokinetics
Absorption
Rapidly and nearly completely absorbed from the GI tract. Food may delay the absorption somewhat, but not the extent.
Distribution
In children, the apparent volume of distribution is about 2.5 L/kg.
Metabolism
Only partially metabolized.
Elimination
The bulk is excreted unchanged in the urine. Urine pH can affect excretion rates. Alkaline urine (pH 8) can prolong half-life while acidic urine (pH 5) can decrease it.
Overdose
Overdoses of pseudoephedrine can cause hyperthermia, mydriasis, tachycardia, hypertension, vomiting, disorientation, and seizures.
- Toxicity Thresholds: In small animals, adverse reactions may develop at doses of 5-6 mg/kg. Deaths have occurred at doses >10-12 mg/kg.
- Clinical Signs: Common findings in dogs include hyperactivity, tachycardia, agitation, mydriasis, restlessness, head bobbing, and panting. Cats commonly present with tachycardia.
- Treatment: Large overdoses should be treated with gastric evacuation (if not contraindicated). Treat supportively and symptomatically (e.g., propranolol for tachycardia). Phenothiazines are preferred to treat hyperactivity, agitation, and tremors as diazepam may worsen dysphoria. Contact an animal poison control center for further guidance.
Available products
Formulations
- Capsules
- Extended/Controlled Release Tablets
- Oral Liquid
- Oral Drops
- Oral Granules (with pyrilamine)
Veterinary
- Pseudoephedrine HCl 600 mg/oz and Pyrilamine maleate 600 mg/oz Granules (Equiphed®, Equi-Phar Equi-Hist 1200 Granules®, Tri-Hist® Granules, Histgranules®)
Human-labeled
- Pseudoephedrine HCl Tablets and Capsules: 30 mg & 60 mg
- Extended/Controlled Release Tablets: 120 mg and 240 mg
- Pseudoephedrine Liquid: 3 mg/mL and 6 mg/mL
- Pseudoephedrine Oral Drops: 7.5 mg/0.8 mL
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Oral pseudoephedrine products should be stored at room temperature in tight containers. Oral liquid preparations should be protected from light and freezing.
Client information
- Consistency is Key: For this drug to be effective, it must be administered exactly as directed by the veterinarian. Missed doses will negate its effect (e.g., urine dribbling will return). It may take several days for the full benefit of the drug to take place.
- Watch for Side Effects: Because this drug acts as a stimulant, your pet might become restless, pant more than usual, or lose their appetite.
- When to Call the Vet: Contact your veterinarian immediately if your pet demonstrates ongoing changes in behavior (restlessness, irritability), has a racing heart, or if the urinary incontinence persists or increases.
Safety Warning: Keep this medication strictly out of reach of all pets and children. Even small accidental overdoses can be extremely dangerous.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.