Does melatonin interact with medications?
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Yes, with some. In small studies, the antidepressant fluvoxamine made melatonin levels about 17 times higher, and melatonin raised systolic blood pressure by about 6.5 points in people whose pressure was controlled on nifedipine. If you take a prescription medicine every day, ask your prescriber before you start.
Melatonin is sold next to vitamins, so it rarely makes it onto the list of medicines people mention at a doctor’s visit. But it’s a hormone your body has to clear, and some drugs change how fast that happens or work against it.
If you take a prescription medicine every day, we’d leave any melatonin dose and timing to your prescriber. Melatonin interacts with some medicines, including fluvoxamine, blood thinners and nifedipine, so ask your prescriber before you start.
Fluvoxamine works on melatonin like a plug in a sink drain. The same amount pours in, but it fills much higher because it can’t get out.
The interactions that have been measured
| Medicine | What happened | The study |
|---|---|---|
| Fluvoxamine (an antidepressant) | Melatonin levels about 17 times higher on average | 5 healthy men, 5 mg melatonin with and without 50 mg fluvoxamine, 2000 |
| Nifedipine (a blood pressure drug) | Systolic blood pressure about 6.5 points higher and heart rate up, across 24 hours | 47 people with treated high blood pressure, 5 mg melatonin or placebo at 10:30pm for 4 weeks, 2000 |
| Blood thinners such as warfarin | Case reports of possible harm | Cochrane jet lag review, 2002, and the NCCIH, which says people on blood thinners need medical supervision |
| Epilepsy | Case reports of possible harm | The same review, and the NCCIH says people with epilepsy need medical supervision |
| Some beta blockers | Run the other way, cutting your own melatonin. (S)-propranolol cut overnight melatonin output by 80 percent, and carvedilol didn’t lower it | 15 healthy volunteers, single doses, 1999 |
Fluvoxamine, in more detail
In a 2000 study in Germany, five healthy men took 5 mg of melatonin on its own and again with 50 mg of fluvoxamine. With fluvoxamine, their melatonin levels were on average 17 times higher, and the researchers traced it to slower clearing of melatonin, not to the body making more. The fluvoxamine effect was measured directly. For other antidepressants, including sertraline, ask your prescriber.
Nifedipine, in more detail
In the nifedipine trial, 47 people whose blood pressure was well controlled took melatonin or a placebo each evening for 4 weeks, then swapped. On melatonin their blood pressure and heart rate ran higher across the whole day, with systolic up about 6.5 points. The authors suggested melatonin may compete with the drug. If your prescriber agrees to a trial, measuring your blood pressure at home for a week before and during is a good way to see your own numbers.
Beta blockers and sleep
Some beta blockers lower the melatonin your own brain makes at night, and the 1999 study’s authors noted that sleep problems are a common side effect of these drugs. Don’t change a heart or blood pressure medicine to fix your sleep. Bring it up with the doctor who prescribed it.
Older adults and dementia
The American Academy of Sleep Medicine’s 2015 guideline recommends against melatonin for older people with dementia.
What to bring to your prescriber
The name and strength on your melatonin bottle, how often you take it and at what time, and every other medicine and supplement you take. That’s enough for them to check it against your list.
6 sources
- Härtter S and others, Increased bioavailability of oral melatonin after fluvoxamine coadministration, Clinical Pharmacology and Therapeutics, 2000pubmed.ncbi.nlm.nih.gov
- Lusardi P, Piazza E, Fogari R, Cardiovascular effects of melatonin in hypertensive patients well controlled by nifedipine, British Journal of Clinical Pharmacology, 2000pubmed.ncbi.nlm.nih.gov
- Stoschitzky K and others, Influence of beta-blockers on melatonin release, European Journal of Clinical Pharmacology, 1999pubmed.ncbi.nlm.nih.gov
- Herxheimer A, Petrie KJ, Melatonin for the prevention and treatment of jet lag, Cochrane Database of Systematic Reviews, 2002pubmed.ncbi.nlm.nih.gov
- National Center for Complementary and Integrative Health, Melatonin: What You Need To Know, last updated May 2024nccih.nih.gov
- Auger RR and others, Clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders, an update for 2015, Journal of Clinical Sleep Medicine, 2015pubmed.ncbi.nlm.nih.gov
