By Rania Gollakner, BS, DVM, MPH

What is codeine?

Codeine (brand names: Codeine Contin®, Codeine Phosphate®, Codeine Sulfate®, Codeine 15 or 30) is an opioid medication used to treat mild to moderate pain, cough, and sometimes diarrhea.

In the United States, codeine is considered a class II-controlled substance, which means there are strict rules regarding how it is prescribed, dispensed, and used. Codeine in combination with other medications is still controlled, but typically these combination drugs have different restrictions.

Its use in cats and dogs to treat pain, cough, and diarrhea is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions may be significantly different from those on the label.

How is codeine given?

Codeine is given by mouth in the form of a tablet or liquid solution. It may also be given as an injection in the hospital setting. It may be given with or without food; however if stomach upset occurs when dosed on an empty stomach, give future doses with food. Measure liquid forms carefully. Do not give the combination product containing acetaminophen (Tylenol®) to cats or ferrets.

This medication will take effect quickly, in about 1 to 2 hours, and improvement in clinical signs should follow.

What if I miss giving my pet the medication?

Give the missed dose as soon as you remember, and then wait the recommended amount of time between doses. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

The most common side effects are sleepiness and constipation.

Other possible side effects include lack of appetite or vomiting. Serious side effects include collapse, severely decreased breathing rate, or decreased muscle movement. In cats, serious side effects also include increased excitement, tremors, and seizures.

This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Do not use codeine in pets that are allergic to it or other opioids, in pets with inflammatory bowel disease, or in pets that have ingested a toxic substance. Be careful not to use the combination product containing acetaminophen in cats or ferrets. Codeine should be used cautiously in pets with low thyroid levels, severe kidney disease, head injury, breathing problems, heart disease, or adrenal gland disease. Use codeine cautiously in working, geriatric, debilitated, and pregnant pets. Use in lactating pets appears safe, but use cautiously as adequate studies are lacking.

Codeine and other opioids have human abuse potential; keep these medications in a safe place and ideally in a locked cabinet.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with codeine: anticholinergic drugs, antidepressants, or central nervous system depressants such as anesthetics, barbiturates, or tranquilizers.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

There is no specific monitoring that needs to be done while your pet is taking this medication. Your veterinarian may monitor your pet to be sure that the medication is working. Monitor your pet at home for serious side effects.

How do I store codeine?

Codeine commercial products should be stored at room temperature and protected from light. For specially compounded formulations, follow the specific storage directions on the label.

Codeine is a controlled substance, which means that it has been designated by the Drug Enforcement Administration (DEA) as having a potential for diversion to people other than the patient it was prescribed for. Use of a controlled substance in any person or animal other than that for which it is prescribed is illegal. Therefore, this medication should be stored in a locked cabinet or safe that cannot be easily moved, with access limited to only those that need to administer the medication. Monitor the amount of medication remaining to ensure the expected amount is present.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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