Some important drug interactions can occur with melatonin even though it is a dietary supplement. Always review for drug, food and disease interactions with your healthcare provider anytime you start, or even stop, a medication.
Always tell your doctor and pharmacist about all of the medications you take, including prescription drugs, over-the-counter medicines, vitamins and herbal supplements. Do not stop using any medications without first talking to your doctor.
Talk to your doctor before using melatonin if you take the blood thinner warfarin. Melatonin has been reported to increase the effects of warfarin in some patients. This is not a complete list of drug interactions that may occur with melatonin.
 Melatonin drug interactions (more detail)
Is Melatonin Approved by the FDA?
Melatonin is not approved by the FDA for any use. It falls under the FDA’s Dietary Health and Education Act as a dietary supplement. Dietary supplements may include vitamins, minerals, amino acids, and herbs or botanicals, plus other substances used to supplement the diet. As with other dietary supplements, melatonin isn't approved by the Food and Drug Administration (FDA) for safety or effectiveness.
Manufacturers must notify FDA about new ingredients prior to marketing. After the supplement is on the market, the FDA will monitor adverse events that are reported to them by the manufacturer, consumers or health care professionals. If a manufacturer makes an unproven health claim or if the supplement is found to be unsafe the FDA can remove the OTC from the market.
Avoid buying dietary supplements from the Internet and from online pharmacies whose authenticity you cannot verify. It is important to remember that an OTC label that says “natural” supplement does not always mean it’s “safe” for consumption. Formulations that are United States Pharmacopeial (USP) Convention Verified can be considered most reliable in this regard; the label “USP” is found on the outside of the bottle. For example, all Nature Made products are verified by the USP. The safest way to purchase drugs online is through pharmacies accredited by the Verification of Internet Pharmacy Practice Sites (VIPPS) programs.
Do Electronic Devices Alter Melatonin Levels?
Light at night blocks the production of melatonin, and this has been shown to cause sleep disturbances in people who use electronics that emit light at night. Researchers have found that light from electronic devices can block the release of natural hormone melatonin at night. The effect was most significant for younger children, with nighttime levels reduced by up to 37 percent in certain cases. This can also be problematic for children between ages 9 and 16.
Studies show that light after dark lowers melatonin levels which may lead to difficulty in initiating sleep. Electronic light-emitting devices such as the television, laptops, smartphones and tablets often find their way into the bedroom at night, or are used after dark. Children should not have electronics, including TVs, in their bedroom at bedtime and everyone should avoid use of light-emitting devices and screen time at least one hour before bedtime.
Melatonin Reviews and Studies
For Sleep Disorders
Researchers have conducted many studies on melatonin supplements for various conditions. Most studies have been conducted in sleep disorders, such as jet lag, shift work sleep disorders, delayed sleep phase disorder, and insomnia. Studies are often not consistent in their results and questions still remain about its usefulness, dosage, length of treatment and long-term safety for some sleep conditions.
Melatonin can be effective for jet lag for many people when dosed at the appropriate time. Its effectiveness for insomnia might slightly hasten the amount of time needed to fall asleep, but may not increase the overall sleep time. This medication does appear to be safe for short-term use (less than three months).
For Other Conditions
Multiple areas for melatonin use have been investigated, but not all uses may be accepted or have adequate research to determine appropriate clinical use. These include:
Cancer
Boost the immune system
Sunburn
Irritable Bowel Syndrome (IBS)
Fibromyalgia
Systemic sclerosis
Antioxidant and free radical scavenger
Alzheimer’s disease
Ocular diseases
Sleep aid for children with autism spectrum disorder or attention deficit hyperactivity disorder (ADHD)
Amyotrophic lateral sclerosis (ALS)
Nighttime blood pressure control
Seasonal affective disorder (SAD)
How Does Melatonin Come at the Store?
In the U.S., melatonin pills can be purchased without a prescription in the pharmacy, grocery, or health food store. Pill strengths range from 1 milligram (mg) to 10 mg, but you should always start with the lowest dose to judge its effects. Some experts suggest to start with 0.3 to 0.5 mg thirty minutes before bedtime, instead of the higher doses. Cut a 1-mg immediate release tablet in half to get a 0.5 mg dose if lower doses are not available; don’t do this with time release products. Also, don't drink alcohol with the time-release preparation, as it can disrupt the time-release mechanism.
Does Food Contain Melatonin?
A study published in Food and Nutrition Research notes that certain food products do contain various amounts of melatonin as measured by immunological and chromatographic laboratory techniques. How consumption of these various foods might affect endogenous production sleep or was not evaluated:
Tomatoes
Walnuts
Rice/barley cereal
Strawberries, tart cherries
Olive oil
Wine, beer
Cow’s milk
Research finds that melatonin synthesis depends upon availability of the essential amino acid tryptophan, a needed component of the diet. If intake of tryptophan is severely restricted, synthesis of melatonin is significantly reduced in humans.
In the Nurses’ Health Study, no link was found between the consumption of various nutrients, such as folate, vitamin B6 and zinc and increased urinary excretion.
Diets rich in vegetables, fruits and grain products will contain considerable levels of dietary melatonin. The overall effect of dietary consumption on nighttime levels of melatonin is very limited. Melatonin production is primarily driven by the effects of light and darkness and by age, declining as we get older.
How Much Does Melatonin Cost?
On average a 120-count bottle costs about $10.00, but prices can vary, depending upon the manufacturer and strengths purchased. Insurance usually will not pay for over-the-counter (OTC) products, although some plans may allow use of health savings account funds.
Bottom Line: Pros and Cons
Benefits:
Widely available in the U.S. over-the-counter (OTC) without a prescription
Short-term use (less than 3 months) is relatively safe with little evidence of toxicity
Inexpensive product with generics or store brands available
Lower dose and orally-dissolvable products for children are available
Comes in a variety of dosage forms and doses
Downsides:
Not approved for any uses by the FDA (over-the-counter dietary supplement)
Quality of some products cannot always be assured
Studies for less common uses are not consistent
Doses tend to vary between patients; always ask a medical professional for dosing advice in children
Effective lower doses (0.1 to 1 mg) are not always commercially available
Higher doses (2 to 10 mg) used over a prolonged period may lead to rebound insomnia and are not well studied.
For More Information
Jet Lag Disorder Disease Reference
Jet Lag Health Guide
Melatonin Support Group
Sleep Disorders Support Group
References
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