For most people, melatonin does not raise blood pressure. In fact, clinical trials consistently show the opposite: melatonin supplementation modestly lowers both systolic and diastolic blood pressure. However, there is one important exception. If you take a type of blood pressure medication called a calcium channel blocker, melatonin may interfere with it and push your blood pressure up.
What the Research Actually Shows
A meta-analysis of randomized controlled trials in people with metabolic disorders found that melatonin supplementation significantly reduced both systolic and diastolic blood pressure. This pattern holds across multiple studies: melatonin’s net effect on blood pressure trends downward, not upward.
The type of melatonin matters, though. Controlled-release (also called extended-release or slow-release) melatonin lowered nighttime systolic blood pressure by about 6.1 mmHg and diastolic by about 3.5 mmHg. Fast-release melatonin, the kind most commonly sold in stores, had essentially no effect on blood pressure at all, dropping it by less than half a point in either direction. So if you’re taking a standard quick-dissolve tablet, it’s unlikely to change your blood pressure in any meaningful way.
How Melatonin Affects Blood Vessels
Melatonin interacts with two types of receptors on blood vessel walls, and they do opposite things. One type (MT1) triggers blood vessels to constrict, which would theoretically raise pressure. The other type (MT2) causes blood vessels to relax and widen, which lowers pressure. The net result in most people leans toward relaxation, partly because melatonin also helps protect the lining of blood vessels from oxidative damage and supports the body’s production of nitric oxide, a molecule that naturally keeps vessels flexible and open.
This dual action explains why the blood pressure effects of melatonin are generally modest and vary between individuals. Your body’s balance of these receptors, your baseline blood pressure, and what other medications you’re taking all influence the outcome.
The Calcium Channel Blocker Problem
This is the scenario where melatonin can genuinely raise blood pressure. In a double-blind study of 47 people whose high blood pressure was well controlled with nifedipine (a calcium channel blocker), taking 5 mg of melatonin at bedtime raised systolic blood pressure by 6.5 mmHg and diastolic by 4.9 mmHg over a 24-hour period. Heart rate also increased by about 4 beats per minute.
The likely explanation is that melatonin competes with nifedipine at the cellular level, reducing the drug’s ability to keep blood vessels relaxed. The researchers concluded that melatonin “cannot be considered simply a dietary supplement” for people on this type of medication. This interaction hasn’t been studied as thoroughly with other calcium channel blockers, but the concern applies to the entire drug class. If you take amlodipine, diltiazem, verapamil, or any related medication, this finding is directly relevant to you.
Dosage and Formulation Details
The studies that found blood pressure reductions used controlled-release melatonin in doses ranging from 2 mg to 2.5 mg, with one study going as high as 24 mg. The blood pressure-lowering effect appeared most reliably at the lower doses in controlled-release form. The study that found blood pressure increases used 5 mg of immediate-release melatonin in people on nifedipine.
Most melatonin supplements sold over the counter in the U.S. are immediate-release formulations in doses of 1 to 10 mg. Controlled-release versions are available but less common and usually labeled as “extended release” or “time release.” If you’re specifically interested in melatonin’s blood pressure effects, the formulation you choose makes a meaningful difference. Immediate-release melatonin, on its own, appears to be largely blood pressure neutral.
Long-Term Use and Safety Concerns
The American Heart Association’s 2025 scientific statement on sleep health flagged that melatonin “should not be taken chronically without a proper indication.” In the U.S., melatonin is sold as a dietary supplement rather than a regulated medication, which means there’s no standardized oversight of dose accuracy or purity. Studies have found that the actual melatonin content in supplements can vary significantly from what’s listed on the label.
For people without cardiovascular conditions who aren’t on blood pressure medications, short-term melatonin use at standard doses (0.5 to 5 mg) is generally well tolerated and unlikely to raise blood pressure. The risk profile changes if you have high blood pressure that’s being managed with medication, particularly calcium channel blockers. In that case, adding melatonin without discussing it with your prescriber could undermine your treatment in a way that’s measurable on a blood pressure cuff.