Is Melatonin Safe?

Short answer: yes.

Longer answer: Nothing is perfectly safe. There is probably someone out there allergic to melatonin, and I’d be the last person to tell them they’re not.

With anything you’re taking if you notice a dramatic change in how you feel, immediately suspect it.  Maybe the change is good (like antibiotics for bacterial infections) but when it’s bad don’t delay in asking about it. We lose way too many people every year from drug interactions because they didn’t speak up about serious side effects.

That said, melatonin is about as safe as they come. It’s a natural body product, so your liver should know how to break it down and there shouldn’t be a build up in your system.  

But a patient recently asked me about melatonin for children, because there seems to be some new concerns about it causing problems. 

I went on the web, that bastion of all wisdom and knowledge. It seems like the number one writer questioning melatonin is a registered dietitian from New Zealand, where melatonin is prescription only. His conclusion is that it’s safe, but he quotes a long list of side effects.

(In full disclosure, I also made a similar case for possible side effects in 2014. I’m not a fan of people living on melatonin forever). 

The side effects list the dietitian uses comes from a review of insomnia aids for ADHD children, which shouldn’t be applied to the general population. That review covers a wide range of things. It ends up making judgments based on only five articles. “Despite the dearth of evidence… antihistaminergic medications, tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRI), benzodiazepines, antipsychotics, serotonin 2 antagonist/reuptake inhibitors (SARI, e.g. trazodone), α-adrenergic agonists, or exogenous melatonin…” 

There’s a lot of things to cover here, and only one of them is not prescription. It makes me suspect bias, putting melatonin in with a wide range of fairly toxic pharmaceutical drugs. It’s a bit like seeing a bunch of heavy metals listed as possible treatments and then seeing dandelion added in at the end. Which one of these is a non-prescription supplement without strict FDA oversight and manufacturing practices?

Being me, I have to go into the full article. It quotes a double-blind melatonin study (2007) that helped with sleep and found “No significant adverse effects or discontinuation because of adverse events.” 

That study was followed up years later by a parental questionnaire. In that follow-up questionnaire survey over 80% of children were still happily on melatonin doses from 0.5 to 10 mg four years later.  Another 9% had stopped melatonin because they didn’t need it. But let’s not focus on the overwhelming nontoxic, successful treatment. Let’s focus on the report that, ” Three patients (3.1%) discontinued because of adverse effects. Parents of 7 children (7.4%) reported unexpected comorbidity.” 

 One would hope that a double-blind study would be given greater weight than a parent survey four years later, but this review gives them equal weight.

Remember, the review covers a lot of other drugs. Of all the drugs used, melatonin is the only one that is both effective and non-toxic.

But instead of promoting melatonin, the review concludes that nothing should be given. The reviewer goes out of his way to list all the side effects in the first study, “Ten children (18.9%) experienced adverse events such as headaches (5.7%), hyperactivity (5.7%), dizziness (3.8%), and abdominal pain (3.8%), but no patients withdrew from treatment.” Notice the report of hyperactivity as a side effect in a study of ADHD children. Again, the reviewer does not feel objective in the assessment of melatonin.

So the best information we have about melatonin is that it is safe and effective short term even for children with ADHD.

Bottom line, it is theoretically possible to have a side effect from melatonin the same way it is possible to have a side effect from ginger or turmeric (I have a patient possibly dealing with one of those). But we do not expect melatonin to do bad things any more than we’d expect a doorknob to break off in our hands. It might happen, but it shouldn’t keep us awake at night.

And if it does, melatonin will likely help us fall asleep.  But other things can help as well. See my insomnia checklist

Doodle by C. Maloney

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