What is acetaminophen/codeine?
Acetaminophen with codeine (brand name Tylenol with Codeine, Tylenol #3) is a combination drug used for pain management in humans. Acetaminophen is a pain reliever and fever reducer. It is not often used in animals and, when done so, must only be used in dogs. It is often combined with the drug codeine, which is a narcotic pain reliever. Codeine is also known as an anti-cough medication in humans, but in animals the effects of this drug are not well known.
There is no approved veterinary brand of acetaminophen/codeine. It is used off label to treat pain in dogs. Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the FDA or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as their directions may be significantly different from those on the label.
NEVER use in CATS or FERRETS. In these species, acetaminophen is toxic at any dose.
How is acetaminophen/codeine given?
Acetaminophen/codeine comes as tablets, elixirs, and liquid solutions in many different formulations (e.g., 300 mg acetaminophen plus 15 mg, 30 mg, or 60 mg codeine).
- Tablets, elixirs, and liquid solutions are given orally (by mouth).
- May be given with food or on an empty stomach. If your dog vomits or appears unwell after giving the medication on an empty stomach, try giving the next dose with a small amount of food. Contact your veterinarian if the vomiting persists.
- Follow your veterinarian’s directions and measure liquid forms of this medication carefully, using a medication measuring device.
- Do not give with other pain- or fever-reducing medicines unless instructed by your veterinarian.
- Avoid using generic versions of acetaminophen/codeine that may contain other ingredients such as ibuprofen or caffeine.
- Do not stop this medication suddenly.
- Ideally, give this medication at the same time every day.
This medication should take effect within 1 to 2 hours and improvement in clinical signs should follow. It is short-acting, meaning that effects should stop after 24 hours but may be prolonged in pets with kidney and/or liver disease.
What if I miss giving my pet the medication?
If you miss a dose of acetaminophen, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.
Are there any potential side effects?
Acetaminophen/codeine may cause the following side effects:
- sleepiness
- constipation
- reduced appetite
- vomiting
- diarrhea
The following reactions are rare; if they occur, contact your veterinarian immediately:
- loss of appetite
- yellowing of the whites of the eyes, skin, or gums (jaundice)
- vomiting or diarrhea that persists or worsens
- blood in vomit (looks like coffee grounds) or in stools (black, tarry)
Drug sensitivities can develop over time, with repeated exposure. Your pet may have no reaction after the first few doses but may develop a sensitivity later. It is important to watch for signs of an allergic reaction over the entire course of treatment.
Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately.
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?
This medication SHOULD NOT BE USED in:
- cats and ferrets: even small amounts of acetaminophen/codeine in these species can be fatal
- hedgehogs and sugar gliders: it is not known if acetaminophen/codeine is safe for these animals
This medication SHOULD NOT BE USED in dogs who:
- are allergic to it
- are taking other pain medications (unless directed by your veterinarian)
- are dehydrated or have low blood pressure, due to risk of kidney injury
NEVER give to a dog without a veterinarian's advice. Although acetaminophen/codeine is not poisonous to dogs, it is not as safe to use in dogs as it is in humans.
This medication should be USED WITH CAUTION in dogs who:
- have liver disease
- have gastrointestinal problems, due to the risk of constipation
- have severe kidney disease
- have breathing problems
- have bleeding disorders
- have Addison’s disease (low cortisol levels)
- have low thyroid hormone levels
- are young or very old
- are in a poor state of health
- will have surgery in the near future
- are breeding, pregnant, or nursing, as safety has not been established
Are there any drug interactions I should be aware of?
Be sure to tell your veterinarian about any medications (including vitamins, supplements or herbal therapies) that your dog is taking before starting any treatment.
Certain medications SHOULD NOT BE USED with acetaminophen/codeine, including:
- steroids (e.g., prednisone, dexamethasone), unless directed by your veterinarian
- drugs that may be toxic to the kidney
- aspirin (acetylsalicylic acid) or drugs that contain aspirin
Certain medications should be used WITH CAUTION when given with acetaminophen/codeine, including:
- fenbendazole (dewormer): can worsen liver toxicity.
- anticonvulsants (e.g., phenylbarbital, pregabalin): may increase susceptibility to acetaminophen-induced liver injury.
- selegiline (Anipryl, Eldepryl®, l-deprenyl, Selgian®, Zelapar®): the metabolism of this drug can be decreased when combined with acetaminophen/codeine.
- other oral, anti-clotting medications: can increase anti-clotting activity.
Is any monitoring needed with this medication?
- Baseline blood work should be performed before starting your dog on acetaminophen/codeine to assess general health.
- Your veterinarian may recommend periodic bloodwork if your dog is receiving acetaminophen/codeine for long periods
- Tear production should be monitored for 72 hours following exposure to higher-than-normal doses of acetaminophen in dogs.
At home, monitor for any side effects such as those noted above. If any side effects occur, discontinue the medication and contact your veterinarian.
How do I store acetaminophen/codeine?
- Store this medication at room temperature, in a tightly sealed container, out of direct sunlight.
- Keep the container out of reach of children and pets.
- Store compounded forms of this medication according to the label.
Acetaminophen/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.
Ask your veterinarian for specific disposal instructions. Do not flush medicines down the sink or toilet unless instructed to do so.
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. Be prepared to provide information about the product and your pet's weight and symptoms.
