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Melatonin and Medication Interactions

Melatonin, a popular over-the-counter supplement, is widely used for its sleep-inducing properties. However, its interaction with various medications can lead to significant health risks. This article explores nine potential drug interactions with melatonin, providing crucial information for those considering its use.

1. Antidepressants

Certain antidepressants, such as fluoxetine (Prozac) and citalopram (Celexa), can increase melatonin levels in the body. This interaction may lead to enhanced drowsiness, headaches, and gastrointestinal issues. Some selective serotonin reuptake inhibitors (SSRIs), when combined with melatonin, can also pose a risk of serotonin syndrome, a serious condition characterized by confusion, high fever, and sweating.

2. Nifedipine

Nifedipine (Procardia), a calcium channel blocker used to treat high blood pressure, may become less effective when taken with melatonin. This interaction can result in elevated blood pressure, increasing the risk of cardiovascular events.

3. Blood Thinners

Warfarin (Coumadin) and other blood thinners can interact with melatonin, enhancing their effects and raising the risk of bleeding. Regular monitoring of blood tests is essential when starting or stopping melatonin while on these medications.

4. Sedative Medications and Substances

Melatonin can amplify the sedative effects of various medications and substances, including benzodiazepines (e.g., diazepam), opioids, antihistamines (e.g., diphenhydramine), and alcohol. This interaction can lead to excessive drowsiness and impaired cognitive function.

5. Caffeine

Caffeine can increase melatonin levels by inhibiting its breakdown in the liver. Although this interaction is typically insignificant due to the timing of melatonin consumption, it is advisable to avoid caffeine close to bedtime.

6. Oral Contraceptives

Oral contraceptive pills may increase melatonin levels in the body, potentially leading to side effects such as drowsiness. Starting with a low dose of melatonin is recommended for those on birth control pills.

7. Diabetes Medications

Melatonin may lower blood sugar levels, posing a risk of hypoglycemia when combined with diabetes medications. Monitoring blood glucose levels and consulting with a healthcare provider before starting melatonin is essential for those with diabetes.

8. Blood Pressure Medications

Melatonin can lower blood pressure, particularly in older adults. Combining it with other blood pressure-lowering medications can result in hypotension, causing dizziness, weakness, or fainting.

9. Immunosuppressants

Melatonin can activate the immune system, potentially reducing the effectiveness of immunosuppressant medications used for autoimmune conditions or post-organ transplant. Consulting with a healthcare provider for alternative sleep aids is recommended for those on immunosuppressants.

Additional Considerations Regarding Melatonin


Some antibiotics, such as fluoroquinolones and erythromycin, may increase melatonin levels. While this interaction is typically not a major concern due to the short duration of antibiotic treatment, it may be wise to adjust the melatonin dosage during antibiotic use.


There appears to be no significant interaction between melatonin and acetaminophen (Tylenol). However, consulting with a pharmacist or healthcare provider is always recommended to ensure safety based on individual health conditions and medication profiles.

When to Seek Medical Advice

It is crucial to consult with your healthcare team before starting melatonin to identify any potential interactions with your current medications. If you experience new or worsening symptoms while taking melatonin, seek medical advice promptly. In severe cases, such as signs of serious bleeding or serotonin syndrome, emergency care may be necessary.

Melatonin can be a helpful supplement for improving sleep, but its interactions with various medications necessitate caution. By consulting with healthcare providers and staying informed about potential interactions, you can safely incorporate melatonin into your health regimen.

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