What side effects might my child show if they take melatonin?

This blog is part of my series on “Should I Give My Child with Autism Melatonin to Sleep?” The goal of my series is to help you figure out if melatonin is right for your child.

Even though melatonin is a natural substance, melatonin supplements are a medicine. Medicines have side effects. Side effects are symptoms that you don’t want your child to have. These may include dizziness, stomach problems, or nightmares.

How do you know if these symptoms are from melatonin? To answer this question, you want to compare these symptoms in children who take melatonin and children who don’t take melatonin, and make sure the percent of children that have symptoms is higher in those taking melatonin.

For example, when I first moved to Tennessee, I noted that a lot of kids with autism had seasonal allergies (sneezing, itchy eyes, runny nose) and questioned whether autism was linked to allergies. That was before I realized that Tennessee was one of the allergy capitals of the world! There actually wasn’t a link between autism and allergies. I was just seeing kids with autism in a part of the country with high rates of allergies.

Here’s a study that compared the percent of symptoms in two groups of children. One group was taking melatonin and one group was taking placebo. A placebo is a pill that looks like the drug of interest but doesn’t have melatonin in it.

Table 1. Comparison of symptoms in children taking melatonin vs. placebo. SOURCE: J Am Acad Child Adolesc Psychiatry. Nov 2017.

At first glance, you might think that mood swings are caused by melatonin. But the mood swings may simply reflect how common mood swings are in autism. When you compare the group taking melatonin to those taking placebo, mood swings were actually more common in the group that didn’t take melatonin. Vomiting was about the same in both groups. Headache, on the other hand, was more common in those taking melatonin. So if your child tends to have headaches, you may want to stay away from giving your child melatonin. Or you can start your child on melatonin and watch how they do. If they do fine, you can continue melatonin. But if they start having more headaches, that may be a signal to stop melatonin.

I hope you will read more of my blogs, and learn how to decide if melatonin makes sense for your child.