Codeine Side Effects in Dogs

Codeine is a medication that is commonly used in dogs.This medication is similar to morphine and is derived from the opium poppy. Codeine is a prescription medication that must be prescribed for dogs by a veterinarian as an extra label drug because it is only approved for human use. Codeine is used for pain relief, cough suppression and sedation and is commonly prescribed for dogs, but is avoided in cats because cats are sensitive to morphine-like drugs.

  1. Drug Allergy

    • Codeine must not be prescribed for dogs that have a known allergy or sensitivity to the drug. Codeine may cause a life-threatening allergic reaction in dogs. Symptoms of an allergic reaction to codeine may include swelling of the lips, swelling of the tongue, wheezing, difficulty breathing and hives. This condition may require emergency medical attention.

    Gastrointestinal Effects

    • Codeine may cause gastrointestinal side effects in dogs that may be bothersome. One side effect of codeine is constipation. This effect is common and many veterinarians prescribe codeine as an antidiarrheal. Vomiting may also occur with use of codeine. This medication should be used with caution in dogs that have gastrointestinal conditions, urinary conditions, kidney disease or liver failure to avoid exacerbating preexisting conditions.

    Respiratory Depression

    • According to Petplace.com, codeine is classified as a narcotic and may be addictive. At higher doses, codeine may cause depression of the respiratory system and should not be used in dogs with preexisting respiratory conditions such as asthma, pneumonia and chronic heart failure. If used in dogs with respiratory problems, codeine can depress the respiratory system to a point that the dog may have difficulty breathing or may stop breathing. Since codeine depresses the respiratory system, it should not be combined with any medications that may also cause a decrease in respiratory function. Some medications such as rifampin, phenobarbital and dexamethasone are a few medications that may interact with codeine in a negative way.