Melatonin Drug Interactions, Risks and Contraindications

Melatonin is a hormone produced naturally by the pineal gland in the brain. The purpose of this hormone is to regulate the circadian rhythm, as well as a number of other functions in the body.

Unfortunately, some people do not produce and/or process this hormone properly. In these cases, melatonin supplements may be beneficial, helping to restore normal sleep patterns and improving daytime alertness.

Before using a melatonin supplement, it is important to learn about the risk of side effects and potential complications that could occur when combining this sleep aid with other medicines or supplements.

Melatonin is rated as Likely Safe when used appropriately by adults. However, there are several potential melatonin drug interactions that you should be aware of to avoid adverse effects. Some of these are discussed below, but you should check with a doctor before using this supplement if you are taking any prescription medications or have a serious health condition.

Melatonin

Sleep Supplement

Sleep

Calmness

Daytime Alertness

How It Works:

• Reduces insomnia, jet lag & daytime fatigue
• Promotes restful sleep & calm mood
• Supports brain function, wellbeing & anti-aging

Dosage:

Between 0.5 - 5 mg per day

Safety:

Rated Likely Safe

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About Melatonin Supplements

Melatonin supplements include pills, creams, lozenges or liquids that contain either natural or synthetic melatonin. People use these products when they have symptoms that may be related to a lack of melatonin or poor regulation of this hormone.

While products containing synthetic melatonin are produced entirely in a laboratory, products containing natural melatonin contain hormones produced by the glands of various animals. The latter is very rare.
Melatonin can be used to treat a number of ailments ranging from fibromyalgia to schizophrenia. However, this supplement is most commonly used to treat sleep-related disorders, such as insomnia, delayed sleep phase syndrome, jet lag and sleep-wake cycle disturbances.

Although limited research exists with regard to the safety of melatonin for children, the supplement has been used to treat people of all ages.

Melatonin Instructions and Dosage

The way in which an individual should use or consume melatonin depends on the type of supplement purchased. For example, creams should be applied to the skin, while liquids should be consumed orally.

Regardless of the preparation, you should always use melatonin supplements as directed by the product label.

The proper dosage of melatonin varies based on the supplement’s intended purpose, as well as the age of the consumer. However, most melatonin supplements will include recommended dosages of between 1 mg to 5 mg per serving.

When using the supplement for children, always check first with a qualified physician and start with the smallest effective dose.

Does Melatonin Interact with any Medications?

According to the Natural Medicines Database, melatonin supplements are considered “likely safe” when used for up to 6 months in adults and “possibly safe” for children when given orally as a single dose.

Melatonin has also been used on a short-term basis in children without noticeable complications. Nonetheless, melatonin supplements may be dangerous for people who are taking certain medications.

Some possible melatonin drug interactions include:

Verapamil

The calcium channel blocker verapamil may interact with melatonin supplements moderately, increasing the excretion of melatonin.

Interaction Rating: Moderate

Drugs that Lower the Seizure Threshold

Caution should be exercised when taking melatonin with drugs that lower the seizure threshold, such as certain stimulants, narcotics, immunosuppressants, antihistamines, antidepressants, antibiotics, antiarrhythmics and anesthetics.

Some studies have shown that melatonin supplements may increase the risk of seizures, thus enhancing the effects of these medications.

Interaction Rating: Moderate

Nifedipine

Patients should exercise caution when taking melatonin supplements in combination with nifedipine, a drug commonly used to treat hypertension. When taken together, these medications may increase the patient’s systolic blood pressure, diastolic blood pressure and heart rate.

Interaction Rating: Moderate

Methamphetamine

Melatonin supplements may enhance the effects of methamphetamine, leading to a significant reduction in the patient’s dopamine levels. Patients using these substances together should be careful.

Interaction Rating: Moderate

Immunosuppressants

Drugs that suppress the immune system, such as corticosteroids, may not work as effectively when taken with melatonin. Research shows that melatonin can stimulate the function of the immune system, thus counteracting the effects of these medications.

Interaction Rating: Moderate

Fluvoxamine

The SSRI fluvoxamine has been shown to raise melatonin levels. It may also increase the effects of supplemental melatonin significantly. Patients should use caution until they know how these two medications will interact.

Interaction Rating: Moderate

Flumazenil

The benzodiazepine receptor antagonist flumazenil may lower the effectiveness of melatonin supplements.

Interaction Rating: Minor

Contraceptive Drugs

Melatonin interactions with birth control are not severe, but may be bothersome. Contraceptives may increase the amount of melatonin naturally produced, thus enhancing any adverse effects of supplementation.

Interaction Rating: Moderate

CNS Depressants/ Sedatives/Sleep Aids

Melatonin interactions with other sleep aids, CNS depressants and sedatives are also possible. When used together, these substances may produce a stronger sedation.

Interaction Rating: Moderate

Caffeine

Consumption of caffeine may decrease the body’s production of natural melatonin. However, when combined with melatonin supplements, caffeine may have the opposite effect, thus increasing serum levels and adding to the effects of the supplement.

Interaction Rating: Moderate

Blood Pressure Medications

Taking melatonin may lower systolic and diastolic blood pressure in healthy adults, as well as individuals with hypertension. However, in patients who are taking blood pressure medications, melatonin may worsen blood pressure.

Patients should be cautious when using melatonin and blood pressure medications concurrently.

Interaction Rating: Moderate

Diabetes Medications

Research isn’t clear with regard to the effect of melatonin on glucose levels in patients taking diabetes medications. Until more is known, patients should be cautious.

Interaction Rating: Moderate

Anticonvulsants

Melatonin may inhibit the effects of anticonvulsant medications, such as gabapentin and phenobarbital.

Interaction Rating: Moderate

Anticoagulants

Patients who are taking blood thinners such as warfarin should use caution when consuming melatonin due to a potential drug interaction. This supplement may enhance the effects of the blood thinner, thus increasing the risk of dangerous blood loss.

Interaction Rating: Moderate

Melatonin Contraindications

Studies have shown that melatonin is generally safe for healthy adults. However, some conditions may increase the chances of complications.

According to the Natural Medicines Database, people with the following conditions should use melatonin with caution:

• Seizure disorders
• Hypertension
• Diabetes
• Depression
• Bleeding disorders
• History of transplant

This list is not exhaustive. You should check with a doctor to be sure that you are not at risk for a melatonin drug interaction or adverse effect before using this supplement.

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