Major Uses

Loperamide is an opiate that increases muscle tone in the intestines to improve water and nutrient absorption and decrease diarrhea. This drug may also work to tighten the internal anal sphincter, which helps fecal incontinence. In some cases, loperamide may be used to treat acute colitis or other conditions.

Loperamide is not approved by the Food and Drug Administration for use in animals, but it is prescribed legally as an extra-label drug by veterinarians, primarily for use in dogs. Use in cats is controversial; some felines react to loperamide with excitatory behavior.

Common Precautions

Side effects associated with use of loperamide are uncommon and rarely serious. Constipation and bloating may occur in some dogs, and tranquilization is a possibility.

Use of loperamide may cause falsely elevated amylase and lipase levels normally associated with pancreatitis. Caution is necessary when using this drug in animals with lung disease, head injuries, and acute abdominal pain. It is not known if loperamide is safe for use in pregnant animals. Loperamide is not for the treatment of diarrhea associated with parvovirus enteritis, liver failure, or other intestinal toxins. This medication should not be used by debilitated animals or those with Addison's disease, increased pressure inside the skull, or hypothyroidism without caution and veterinarian approval.

Loperamide is influenced by the P-1 gene mutation that commonly affects Collies and some other breeds. Any breed at risk of having this mutation, including Collies, Old English Sheepdogs, Australian Shepherds, Shetland Sheepdogs, and others should undergo testing to determine P-1 mutation status before using loperamide.

Loperamide and other opiates should not be given to animals taking L-Deprenyl or other monoamine oxidase inhibitors. Additionally, loperamide may cause excessive sedation when used along with antihistamines and tranquilizers

Loperamide should not be used in animals with a known allergy or hypersensitivity to the drug. Overdose of loperamide is a medical emergency that may cause nervous system depression or stimulation or result in respiratory distress.


Loperamide should be stored in its original packaging, away from extreme temperatures, and out of the reach of children and animals.


Loperamide is available in caplet form and as an oral liquid.

A typical dose of loperamide is 0.04 mg/lb (0.08 mg/kg) three to four times daily, or 1 capsule (2 mg) per 50 pounds (25 kg) in animals weighing over 20 pounds (10 kg). Animals weighing under 20 pounds (10 kg) should only be dosed with the liquid form of loperamide due to the potential for overdose. If a dose of loperamide is missed, it should be taken as soon as possible. Because the potential for overdose is high, two doses of this medication should never be taken at the same time.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.