Is Melatonin Bad for Dogs?

Melatonin supplements are available over the counter at most pet stores and online retailers. But can melatonin hurt a dog? If you’re interested in giving your dog melatonin, there are a few things you need to know before you start administering it.

Will melatonin hurt a dog

Will melatonin hurt a dog?

While melatonin is generally considered safe for dogs, it is important to note that it is not FDA-approved for use in animals. This means that there is limited research on its long-term effects and potential side effects.

Some studies have suggested that melatonin may be effective in helping dogs with separation anxiety, but more research is needed to confirm these findings.

Melatonin is typically given in small doses, usually between 0.5 and 3 mg per dog. It is important to follow the dosage instructions on the label or as recommended by your veterinarian.

Overdosing on melatonin can cause side effects such as drowsiness, confusion, and disorientation. It is important to monitor your dog for any unusual behavior or symptoms after administering melatonin.

Dogs with certain medical conditions, such as diabetes or heart disease, should not take melatonin without consulting a veterinarian. Additionally, melatonin should not be given to dogs who are taking other medications, as it may interact with certain drugs.

How long does it take for melatonin to work on a dog?

According to a study published in the Journal of Veterinary Pharmacology and Therapeutics, the onset of action of melatonin in dogs is relatively quick. The study found that melatonin begins to work within 30 minutes of administration, with peak levels reached within 1-2 hours.

However, the duration of action of melatonin can vary depending on the dose and the individual dog. A study published in the Journal of Small Animal Practice found that the duration of action of melatonin in dogs ranges from 4-8 hours, with some dogs showing effects for up to 12 hours.

It is important to note that melatonin is not a quick fix for sleep-related issues in dogs. It may take several weeks of consistent use for the full effects to be seen. Additionally, it is important to consult with a veterinarian before administering melatonin to a dog. The veterinarian can help determine the appropriate dose and monitor the dog for any potential side effects.

How much melatonin can I give my dog?

The following chart can be used as a reference for the recommended melatonin dosage for dogs based on their weight:

  • Dogs under 10 pounds: 0.5-1 mg
  • Dogs weighing 10-25 pounds: 1-2 mg
  • Dogs weighing 25-50 pounds: 2-3 mg
  • Dogs weighing 50-100 pounds: 3-6 mg
  • Dogs weighing over 100 pounds: 6-9 mg

These are only general guidelines, and you should always consult with your veterinarian before giving any medication to your dog. Additionally, melatonin should only be given as a short-term solution for sleep issues and should not be used for extended periods of time without consulting with a veterinarian.

What happens if a dog eats a whole bottle of melatonin?

If a dog ingests a whole bottle of melatonin, it can cause a number of adverse reactions. Melatonin is a hormone that helps regulate sleep and wake cycles, but it can also have sedative effects when taken in high doses.

Melatonin can cause drowsiness and sedation in dogs. This can make it difficult for the dog to stay awake and alert, and can also lead to difficulty walking or coordination problems. In severe cases, a dog may even become comatose.

Additionally, melatonin can also cause vomiting and diarrhea in dogs. This is because the hormone can irritate the stomach lining and cause digestive issues.

Melatonin can cause the heart to beat faster than normal, which can be dangerous for dogs with pre-existing heart conditions. If a dog is showing signs of a fast heart rate, such as panting or restlessness, it is important to seek veterinary care right away.

In severe cases, melatonin overdose can also lead to seizures in dogs. Seizures are a serious medical emergency and require immediate veterinary attention.

Conclusion of melatonin for dogs

Melatonin is a hormone that is naturally produced in the body and is responsible for regulating the sleep-wake cycle. In recent years, it has been used as a supplement for dogs to help alleviate symptoms of insomnia, anxiety, and other sleep-related issues. While melatonin has been found to be safe for use in dogs, there are some potential side effects and contraindications that should be considered before administering it to your pet.


  • Melatonin is an effective supplement for dogs suffering from insomnia or other sleep-related issues. It has been found to help dogs fall asleep faster and stay asleep longer, which can improve their overall quality of life.
  • Melatonin is a non-habit-forming supplement, so it can be used long-term without the risk of addiction.
  • It is a natural hormone that is produced by the body, making it a safe alternative to prescription medications for treating sleep-related issues in dogs.


  • Melatonin should not be used in dogs that are pregnant or nursing, as it can affect the development of their offspring.
  • It can cause drowsiness, which can be dangerous if your dog is left unsupervised or is not able to move around safely.
  • Some dogs may experience side effects such as dry mouth, increased thirst, and increased urination, which may require a lower dose or discontinuation of the supplement.

Side effects:

  • Drowsiness is the most common side effect of melatonin in dogs.
  • Some dogs may experience an increase in appetite and thirst.
  • Some dogs may experience dry mouth, increased urination, and changes in their coat.


  • Melatonin is considered to be non-toxic to dogs when used as directed. However, if your dog ingests a large amount of melatonin, it can lead to symptoms such as sedation, vomiting, and tremors.

Drug interactions:

  • Melatonin can interact with other medications, so it is important to inform your veterinarian if your dog is taking any other supplements or medications.


  • Melatonin should not be used in dogs that are pregnant or nursing.
  • It should not be used in dogs with a history of seizures or other neurological disorders.

Research and study:

  • Melatonin has been extensively studied in dogs and has been found to be safe and effective for use in treating insomnia and other sleep-related issues.
  • A study published in the Journal of Veterinary Internal Medicine found that melatonin was effective in reducing the time it took for dogs to fall asleep and increasing the duration of their sleep.

Natural or OTC veterinary alternatives:

  • Some natural alternatives to melatonin include valerian root and passionflower, which have been found to have a calming effect on dogs.
  • OTC veterinary alternatives include supplements such as chamomile, 5-HTP, and L-theanine, which have been found to be effective in reducing anxiety and promoting relaxation in dogs.


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Hannah Elizabeth is an English animal behavior author, having written for several online publications. With a degree in Animal Behaviour and over a decade of practical animal husbandry experience, Hannah's articles cover everything from pet care to wildlife conservation. When she isn't creating content for blog posts, Hannah enjoys long walks with her Rottweiler cross Senna, reading fantasy novels and breeding aquarium shrimp.

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