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sleeping dog after eating melatonin

My Dog Ate a Melatonin — Is it Dangerous?

Dogs, just like children, sometimes eat things they shouldn’t out of curiosity. We look at the risks of a dog eating melatonin.

Sometimes it can be very difficult to keep a nosy dog away from foods and goodies that aren’t for them, and many dog owners are very familiar with that feeling of anxiety that arises when their pooch gobbles up something they aren’t supposed to eat. So what happens if your dog eats a melatonin?

In most cases, melatonin supplements are not harmful to dogs. That said, larger quantities of the substance can produce unwanted side effects and can be dangerous for dogs who have certain health conditions or who are taking certain other medications. 

What Does Melatonin Do?

Melatonin is a hormone produced by the pineal gland in the brain that acts on the sleep-wake cycles of mammals, including both dogs and humans. 

While our bodies naturally produce melatonin at night, some individuals who struggle with disruptions to their sleep pattern—such as insomnia—may be helped by taking melatonin supplements as a natural sleep aid. Additionally, melatonin may be taken preventatively to combat sleeplessness arising from jet lag. 

Melatonin can be a good option for people struggling with sleeplessness because it is not habit-forming and its continued use does not result in tolerance unlike certain other sleep aids. 

Though melatonin supplements are not FDA approved, they are generally helpful for humans who need help regulating their sleep cycles. While these supplements are not known to be toxic to dogs, it is possible for certain side effects to occur, especially when taken in large doses. 

A regular dose of melatonin for a human is about 3-6 milligrams (mg). Side effects of melatonin that may occur from larger doses include extended drowsiness, nausea, and headaches. Though melatonin is meant to be used as a sleep aid, larger doses may also paradoxically hinder the sleep process. 

Possible Symptoms of a Dog That Has Eaten Melatonin

Plain melatonin containing no sweeteners is generally not toxic to dogs. However, depending on how much was ingested and the dog’s general health, some side effects may occur. 

It is important to keep in mind that melatonin commonly causes drowsiness. If your dog ingests a small amount of melatonin and becomes sleepy afterward but exhibits no other symptoms, there is likely no cause for concern. Even so, it is a good idea to keep an eye on a dog who has eaten a supplement that isn’t intended for them.

Symptoms other than sleepiness that a dog might experience after eating a melatonin supplement include nausea, vomiting, diarrhea, increased heart rate or blood pressure, lack of coordination or confusion, weight gain, or changes in fertility (in dogs who aren’t spayed or neutered).

Dogs who are more likely to experience complications from ingesting melatonin include those with liver or kidney problems, those who are diabetic, and those who are already on medications, including meds used for the treatment of anxiety in dogs. 

Because of its effect on the reproductive cycle and fertility hormones, care should also be taken to keep melatonin away from pregnant or nursing dogs and very young puppies.

Generally, a single dose or pill is unlikely to cause a serious reaction, with the exception of melatonin that includes xylitol—more on that below. 

What To Do If Your Dog Ingests Melatonin

The first thing to do if your dog ingested your melatonin is to figure out how much melatonin the dog ate, if possible. Because melatonin can be bought in many forms including pills, gummies, and liquids, determining how much your dog ate may not always be very straightforward. 

In a scenario in which you cannot figure out how much melatonin your dog ate or whether your dog is exhibiting signs of poisoning, you have the option to either seek advice from your veterinarian or a pet poison control helpline—such as the ASPCA Animal Poison Control Center at (888)426-4435—or to wait and see how your dog reacts. Because most canine melatonin supplements do not exceed 6 mg, though, it is a good idea to seek help if the dose was larger than that. 

If you know for a fact that your dog ate a small dose of melatonin (under 6 mg) and your dog is otherwise healthy, waiting may be appropriate; however, if there is a possibility that your dog ate a lot of melatonin, it would be a better idea to take your pup to the vet or call a helpline. 

dog looking guilty after eating melatonin
little puppy border collie lying near people foot

An Additional Complicating Factor: Xylitol

Although many brands and forms of melatonin will not cause harm to your pooch, formulations that include xylitol are toxic to dogs. As with CBD oil, it is important to keep melatonin supplements containing the sweetener safely away from your dog.

NOTE: Xylitol is also sometimes identified as “birch sugar”, “wood sugar”, or “birch bark extract”, so it’s important to make sure these are not listed as ingredients of products you give your dog.

Though xylitol may be used in different types of melatonin supplements, it is most likely to be found in melatonin gummies, especially those that are branded as sugar free. If your dog ingests melatonin that includes xylitol in its ingredients, it is imperative that you take your dog to the vet or contact pet poison control ASAP. 

Melatonin Made for Dogs

Although there are many melatonin formulations intended for humans that will not harm your dog, if you choose to give your dog melatonin, the best kind is one made specifically for canines. Doses of melatonin for dogs are small, generally ranging from 1-6 mg, given once or twice a day. The exact dosing will depend on your dog’s size and health conditions—guidance is best provided by a vet.

Dogs are not nocturnal by nature, but there are many reasons why dogs may not sleep at night. You should try to diagnose the root cause of your dog’s sleeplessness before simply medicating it.

In addition to helping combat sleeplessness, melatonin may help dogs who are struggling with cognitive dysfunction brought about by Canine Cognitive Dysfunction (sometimes called “dog dementia”), separation anxiety or general anxiety, or certain types of canine alopecia. 

That said, many of these conditions and problems may have causes that are better addressed with other medications your vet could prescribe. As with any supplement, it is always a good idea to consult your vet before giving it to your dog, especially if your dog has preexisting health conditions. 


In many cases, a dog who has ingested melatonin will be fine, though likely drowsy for a while. If your dog ate a large dose, has preexisting health conditions, or takes medications, though, it is best to call your vet or poison control. 

Melatonin supplements—including melatonin gummies—containing xylitol are toxic for dogs. However, those that do not contain the sweetener are unlikely to cause symptoms other than sleepiness or nausea. 

Dogs may experience health problems that can be improved with melatonin supplements; however, it is important to first consult with a vet and to avoid giving your dog melatonin intended for humans. 

Chelsea Dickan

Chelsea Dickan

Chelsea Dickan is a long-time advocate for animals, especially those that bark or meow. When she isn't writing, she enjoys reading and watching scary movies in which the dog doesn't die.