Pyrilamine Maleate
Also known as: Histall, Equiphed, Anihist, Alergitanil, Antemesyl, Anthisan, Equi-Phar Equi-Hist, Fluidasa, Histagranules, Histamed, Mepyraderm, Mepyrimal, Pyramine, Pyriped, Relaxa-Tabs, TriHist
Pyrilamine is an antihistamine used primarily to treat allergic reactions, hives, and respiratory allergies in horses. * **What to Expect**: It helps reduce swelling, itching, and allergic airway responses. * **Side Effects**: Watch your animal closely for changes in behavior. Some animals may become unusually sleepy (sedated), while others—especially horses—might become nervous, excitable, or uncoordinated. Contact your veterinarian if you notice muscle weakness, tremors, or loss of appetite. * **Competition Horses**: If your horse competes, be aware that this medication is regulated (ARCI Class 3). Do not use it within 72 hours of a sporting event, and consult your governing body's rules regarding withdrawal times. * **Allergy Testing**: If your pet is scheduled for skin allergy testing, this medication must be stopped at least 4 days prior to the test.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- Antihistamine
- Antihistamine
- Adjunctive treatment of aseptic laminitis
- Antihistamine
- Antihistamine (Foals)
- Antihistamine
- Antihistamine
- Antihistamine
- Antihistamine
- Antihistamine
How it is given
Possible side effects
- CNS stimulation (nervousness, insomnia, convulsions, tremors, ataxia)
- Palpitation
- GI disturbances
- CNS depression (sedation)
- Muscular weakness
- Anorexia
- Lassitude
- Incoordination
Cautions & contraindications
- Should not supersede the use of other emergency drugs and procedures (e.g., epinephrine for acute anaphylaxis)
- > **Emergency Use Warning**: Antihistamines are not a substitute for epinephrine and supportive care in cases of severe, acute anaphylaxis. * **Skin Testing**: Antihistamines suppress the wheal and flare response. Discontinue at least 4 days prior to intradermal allergy testing. * **Pregnancy**: Probably safe at usual doses, though high-dose rodent studies showed increased fetal death. No teratogenic effects noted in human studies. * **Nursing**: Unknown if it enters milk. * **Regulatory**: Products containing pseudoephedrine are subject to strict regulations (List 1 chemical) due to illicit methamphetamine manufacturing. Pyrilamine is an ARCI Class 3 drug in racing horses.
Drug interactions
- Anticoagulants (heparin, warfarin): Antihistamines may partially counteract the anticoagulation effects of heparin or warfarin.
- CNS Depressant Drugs: Increased sedation can occur if pyrilamine is combined with other CNS depressant drugs.
- Epinephrine: Pyrilamine may enhance the effects of epinephrine.
Frequently asked questions
What is Pyrilamine Maleate used for in pets?
Pyrilamine is an antihistamine used primarily to treat allergic reactions, hives, and respiratory allergies in horses. * **What to Expect**: It helps reduce swelling, itching, and allergic airway responses. * **Side Effects**: Watch your animal closely for changes in behavior. Some animals may become unusually sleepy (sedated), while others—especially horses—might become nervous, excitable, or uncoordinated. Contact your veterinarian if you notice muscle weakness, tremors, or loss of appetite. * **Competition Horses**: If your horse competes, be aware that this medication is regulated (ARCI Class 3). Do not use it within 72 hours of a sporting event, and consult your governing body's rules regarding withdrawal times. * **Allergy Testing**: If your pet is scheduled for skin allergy testing, this medication must be stopped at least 4 days prior to the test.
Is Pyrilamine Maleate safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
Worried about your pet?
Peqaboo’s AI helps you track symptoms, understand lab reports, and know when to see a vet.
Get the Peqaboo app