Melatonin Side Effects: What You Need to Know Before Taking It

When you reach for melatonin, a hormone your body naturally makes to regulate sleep-wake cycles. Also known as the sleep hormone, it’s one of the most popular over-the-counter aids for jet lag and trouble falling asleep. But just because it’s sold without a prescription doesn’t mean it’s risk-free. Thousands of people take it every night, often without knowing how it might affect their body beyond helping them nod off.

Some common melatonin side effects include dizziness, morning grogginess, and headaches. These aren’t rare—they show up in real-world use, not just lab studies. People also report vivid dreams or even nightmares, which can be unsettling if you’re not expecting them. And while melatonin is often thought of as safe for short-term use, long-term effects are still being studied. What we do know? It can interfere with other hormones, especially in teens, pregnant women, or people with autoimmune conditions. It’s also not a one-size-fits-all fix. Dosing matters: too much can throw off your natural rhythm instead of helping it.

Another thing most people don’t think about: drug interactions, how melatonin reacts with other medications you’re taking. It can make blood thinners like warfarin more potent, reduce the effectiveness of diabetes drugs, or boost the sedative effect of benzodiazepines. If you’re on any regular meds—especially for blood pressure, depression, or immune disorders—you need to check with a pharmacist before adding melatonin to your routine. It’s not just about sleep. It’s about your whole body’s chemistry.

And then there’s the quality issue. Unlike prescription drugs, supplements like melatonin aren’t tightly regulated. Studies have found that some products contain way more—or way less—melatonin than what’s listed on the label. Some even have serotonin or other unlisted ingredients. That’s why you can’t just pick any bottle off the shelf. You need to know what you’re putting in your body.

What you’ll find in the posts below isn’t just a list of symptoms. It’s real-world insight from people who’ve experienced these effects, and from healthcare professionals who’ve seen the consequences. You’ll see how melatonin compares to other sleep aids, what the science says about long-term use, and how to spot when it’s doing more harm than good. No fluff. No marketing. Just what you need to decide if melatonin is right for you—or if there’s a better way to get a good night’s sleep.