Melatonin in Dogs and Cats

Medically Reviewed by Joshua Conrad, PharmD on October 09, 2024
Written by Kathleen Claussen, DVM
5 min read

Melatonin (Dermatonin, Regulin) is a dietary supplement used in dogs and cats. It is also sometimes used in horses, sheep, goats, and ferrets. The only animal that has an FDA-approved use is mink. For other types of animals, use is considered to be “extra-label” or “off-label,” meaning that there is evidence of safe and effective use but the FDA has not approved that use.

Dietary supplements are monitored by the FDA in the U.S., but they are not regulated under the same rules as food or medications. The FDA does not approve dietary supplements for safety or effectiveness, nor does the FDA approve the product label. These measures are the responsibility of the supplement company.

Melatonin is a hormone made by the body. Melatonin supplements are generally well-tolerated in animals. It helps regulate the sleep-wake cycle, mood, and reproduction. It is used extra-label for many issues in dogs including:

  • To calm dogs for veterinary and grooming appointments
  • To treat sleep disorders
  • To help with phobias and anxiety
  • To treat non-allergic hair loss

Melatonin is used in cats to help with sleep disorders and behavior issues.

It is best to discuss this supplement with your veterinarian before starting your pet on it. There are many commercial variations for sale on the market, and they are not all created equally. Melatonin supplements are available without a prescription. Some over-the-counter melatonin supplements intended for humans could be given to animals, as well. Discuss this with your veterinarian so that you get the right amount for your pet.

Melatonin is usually given by mouth as a tablet, sustained-release capsule, or liquid. For occasional use for calming, it is best to give melatonin 1 to 2 hours before the anticipated stressful event. For longer-term use, such as for skin issues or sleep disorders, it is given every day and may take up to 2 months to achieve full effect.

It may take up to 24 hours for melatonin to stop working and leave the body after stopping the supplement.

Melatonin may be given with or without food. If vomiting occurs on an empty stomach, melatonin may be given with a small amount of food or a treat. Measure liquids carefully.

Always follow your veterinarian’s directions for giving medicines to animals. Remember to tell your veterinarian about any medicines, vitamins, supplements, or herbal therapies that you are giving your pet. Talk to your veterinarian before stopping any pet medicines.  

  • Melatonin is quickly absorbed by the body and your pet should feel calmer within 1 to 2 hours.
  • Melatonin can be used to calm many anxiety-related conditions.
  • Melatonin can be beneficial on an as-needed or long-term basis.
  • Melatonin is generally well tolerated by animals.

You and your veterinarian should monitor your pet for improvement of their condition as well as for side effects of the supplement. There are usually no routine blood tests that need to be performed.

Do not use melatonin in animals that are allergic to it. Melatonin should be used with caution in animals that are pregnant, nursing, or breeding. Use melatonin cautiously in animals with liver issues or that have not reached sexual maturity. Use with caution in service or working animals as it may interfere with their ability to perform their duties.

Side effects are uncommon in dogs and cats. Monitor for sedation or sleepiness. Melatonin can reduce levels of cortisol and sex hormones (such as estrogen and progesterone). Melatonin can also interfere with thyroid blood levels.

If you think that your pet is having a serious side effect or may have been overdosed, call your veterinary clinic immediately. If it is outside of regular office hours, contact a local emergency veterinary hospital or an animal poison control center.

You can reach the ASPCA Animal Poison Control Center at 888-426-4435 or the Pet Poison Helpline at 855-764-7661.

Using multiple medicines can sometimes change how your pet’s medicines work or increase your pet’s risk for serious side effects. Always tell your veterinarian about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements that your pet is taking.

In particular, make sure that you discuss if your pet is using any of the following before using melatonin:

Benzodiazepines. Benzodiazepines are sedative medications that are usually prescribed in animals for anxiety, behavioral issues, muscle relaxation, and to minimize seizures. Some of these medicines include Xanax (alprazolam) and Valium (diazepam). Melatonin can increase the effects of benzodiazepines. 

Estrogens. Estrogens are hormones that are prescribed mainly to dogs for management of urinary incontinence (uncontrolled peeing). Some of the estrogen medicines include diethylstilbestrol (DES) and estriol. When using melatonin in combination with an estrogen, the dose of melatonin may need to be reduced.

Warfarin. Warfarin is used to prevent blood clots inside your dog. When taken with melatonin, it may increase the risk of bleeding inside your dog’s stomach or intestines. If they are taken together, you should monitor your dog for signs of bleeding. Ask your veterinarian what to look for.

If you think your pet has taken more melatonin than intended, call your veterinarian or veterinary emergency clinic immediately.

If your pet missed a dose, you can give that dose if it is close to the original dosing time. If it is closer to the next dosing time, skip the missed dose completely and give the next dose at the correct time. Do not double the dose of the medicine.  

  • Keep melatonin out of reach of children.
  • Wash your hands after giving melatonin to your pet.
  • Do not handle melatonin if you are allergic to it.

Melatonin should be stored in a tightly sealed container at room temperature. Avoid exposure to direct sunlight and moisture. Always check the package label for the expiration date and special instructions for handling and storage.