Melatonin side effects: What are the risks?

Melatonin is a hormone that plays a role in sleep. Natural levels of melatonin in the blood are highest at night. Some studies suggest that melatonin supplements might be helpful in treating sleep disorders, such as delayed sleep phase. Melatonin supplements also may provide some relief from insomnia and jet lag.

Melatonin is generally safe for short-term use. More research is needed to better understand its safety and usefulness over the long term. Unlike many sleep medicines, with melatonin, you are unlikely to become dependent on it or see reduced effectiveness over time.

The most common melatonin side effects include:

• Headache.
• Dizziness.
• Nausea.
• Daytime drowsiness.

Other, less common melatonin side effects might include:

• Vivid dreams or nightmares.
• Short-term feelings of depression.
• Irritability.
• Stomach cramps.
• Upset stomach or feeling like you’re going to throw up, called nausea.
• Loose stools.
• Constipation.
• Reduced appetite.
• Issues controlling urine output, called urinary incontinence, at night.
• Raised risk of falls.
• Greater risk of seizures.
• Confusion.
• Mood swings.
• Reduced alertness.

Because melatonin can cause drowsiness, don’t drive or use machinery within five hours of taking it.

Melatonin supplements can interact with some types of medicine, including:

• Medicine that slows blood clotting.
• Medicine that prevents seizures.
• Birth control medicine.
• High blood pressure medicine.
• Diabetes medicine.
• Medicines that suppress the immune system, called immunosuppressants.
• Medicine that is broken down by the liver.

Before you take melatonin supplements, check with your healthcare professional. This is especially important if you have any health conditions or if you’re taking other medicines. Melatonin supplements you can buy without a prescription vary widely in how much melatonin they contain. Your care team can help you decide if melatonin is right for you. They also can help you choose which supplement is a good choice for your situation.

As with any supplement, avoid using melatonin as the first or only solution for sleep issues such as insomnia. It’s best to combine melatonin with lifestyle choices that support overall health. This includes:

• Good nutrition.
• Regular exercise.
• Mind-body practices.
• Good sleep habits.
• Staying in touch with friends and family.
• Spirituality.