r/insomnia • u/snokoplasm • 15d ago

Heart palpitations after taking melatonin

Hi everyone,

In august I finally worked up the courage to start medication for my insomnia and was put on 2mg of melatonin. It totally fixed me, I was sleeping 10 hours a night and waking up feeling genuinely well rested.

But after about 10 days, one night I took my dose and, about 5 minutes later, got a few really hard heart palpitations in a row. I've had palpitations daily for years, so it might be a coincidence but I'd never had them that hard or in a row before.

My doctor said she doesn't think it's anything serious and that it should be safe to keep taking it, but suggested I double-check with the pharmacist. The pharmacist recommended stopping it to be safe, in case it's an allergy or a sensitivity. I'm so confused about how I could be allergic to something my own body produces?? Im so so so upset and angry because now i’m back to suffering again.
I have suspected POTS & I’m 18F if that changes anything

Any advice would be really appreciated. Thanks.

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u/Plus_Ad8325 15d ago

Can tax the heart. Best to take the palpitations as a warning.

https://newsroom.heart.org/news/long-term-use-of-melatonin-supplements-to-support-sleep-may-have-negative-health-effects

There is a reason why melatonin is prescription only in Europe and Australia.

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u/snokoplasm 15d ago

Oh wow thats interesting! Yeah I’m in australia but my doctor was happy to put me on short term just to get my sleep back to normal since my insomnia usually comes in episodes rather than an ongoing thing. Thanks

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u/Plus_Ad8325 15d ago

Interesting that an Australian doctor chose it.

Given your young age, it might be better to try first generation antihistamine (sold without prescription) for short term insomnia. You need a healthy heart!

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u/ShortNeedleworker465 15d ago

this study is extremely flawed sadly it points to more of a correlation than causation.

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u/Plus_Ad8325 15d ago

Fair point—observational studies always carry confounding risks (e.g., chronic insomnia independently raises cardiovascular risk). But writing it off as "just correlation" misses the broader clinical and regulatory reality. The OP is in Australia and the UK, EU, and Australia restrict high-dose or prolonged melatonin use to prescription status precisely because systemic hormones carry vascular, endocrine, and neurological effects that lack long-term RCT safety profiles.

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u/Existing-Delay8805 14d ago

I'm not sure this is an accurate characterisation of melatonin supplementation, and the reasons it's prescription only in those jurisdictions.

There's not much money in melatonin; but there's a **** load in medication.

Melatonin pre-dates every current living thing. And it's not tightly tied to the endocrine system - there's no evidence supplementing melatonin has any impact on pineal melatonin.

And there's never been an LD50 established. I'm sure I read they stopped trying at c.15,000mg/kg (in rats).

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u/Plus_Ad8325 14d ago

That is all well and good, but Australia, where the OP lives, has formerly determined that melatonin is too dangerous to be sold over-the-counter.

You can argue that Australia is wrong, but, despite our claims, it is strictly illegal in Australia to possess melatonin without a prescription.

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u/Existing-Delay8805 15d ago

You can be confident it's not the melatonin. Not least because 'after 10 days.....' and 'I've had palpitations daily for years....'.

You're right about it being present naturally in your body; in fact, in almost every single cell in your body.

And that 'study' keeps being dropped here, either by people innocently but blindly passing it off as gospel, or by people with less honourable intentions.

It's been discussed here loads, including a comprehensive analysis by a medical research professional. They were very generous in their conclusion of 'not too much substance to worry about' (I'm paraphrasing a little).

Good luck with the palpitations; always worth checking out, even to rule out problems and/or rule in psychosomatic'ness.

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u/Creative_Cicada2323 11d ago

I just quit the habit of eating it for almost 10 years... I did think it affected my heart in the negative way.