Melatonin in children: what is known about long-term safety

This page is for parents weighing melatonin for a child. It covers what federal health experts say about cancer, long-term safety, side effects, and accidental swallowing.

Parents who ask if melatonin is linked to cancer are usually asking something bigger. Is it safe to give my child this every night for months or years?

On the cancer question, the melatonin information from the National Center for Complementary and Integrative Health (NCCIH) does not describe any link between melatonin use in children and cancer. On the bigger question, the honest answer is that nobody knows yet, and NCCIH says so directly.

Information on the long-term safety of taking melatonin is lacking. That is the agency's own wording.

It means the studies have not been done at a large enough scale or for a long enough time. It does not mean harm has been found and hidden.

NCCIH notes there are not many studies on children and melatonin at all. This leads to two real gaps. The right dose for children is uncertain. And the effects of taking it for a long time are not known.

Short-term use looks fairly safe for most adults. That reassurance does not automatically stretch to a child taking it every night for two years. The evidence for children just is not there yet.

Melatonin is a hormone, not a vitamin. So the open question is a hormone question.

NCCIH says that because melatonin is a hormone, it is possible that melatonin supplements could affect hormonal development. It names puberty, menstrual cycles, and overproduction of the hormone prolactin. It then adds four words that matter: but we don't know for sure.

Read that carefully. There is a reason to ask the question, but no answer yet either way. It is not a warning, and it is not an all-clear.

In children, reported reactions have usually been mild. NCCIH lists drowsiness, more bedwetting, headache, dizziness, and agitation.

More bedwetting is worth noting, since parents do not always connect it to a sleep supplement. If your child starts a new nighttime supplement and a new nighttime problem shows up, mention that link to a clinician.

In adults, the mild effects most often reported are headache, dizziness, nausea, and sleepiness.

There is one melatonin safety issue backed by hard numbers, and it has nothing to do with hormones or cancer. It is accidental swallowing.

Between 2019 and 2022, there were about 11,000 emergency room visits for unsupervised swallowing by children aged five and younger. Poison control reports for people 19 and under climbed from 8,337 in 2012 to 52,563 in 2021.

If melatonin is in your house, keep it out of reach and out of sight. This is the single most useful safety step you can take, and it matters more urgently than any of the long-term questions above.

NCCIH advises parents to talk with a health care provider before giving melatonin to a child. That advice matters here, since safe dosing in children is not well worked out.

A clinician can also ask why your child is not sleeping. Sleep problems often have a cause that a supplement covers up instead of fixing, such as anxiety, screen habits, breathing trouble during sleep, or stress from a family member's illness.

Sleep suffers for everyone when a household is going through treatment, children included. That is a real problem, and it deserves real attention.

NCCIH's broader stance on complementary products fits here too. Unproven products should not replace or delay standard cancer treatment. Any complementary approach should be discussed with the treating team. For a child in treatment, this talk matters even more. Their medicine list is often long, and drug interactions are a real concern.

• NCCIH — Melatonin: What You Need To Know