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Does Melatonin Expire?

Tom Ryan

Written by

Tom Ryan, Editor

John DeBanto

Medically Reviewed by

John DeBanto, Internal Medicine Physician

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Melatonin, a naturally occurring hormone within the body, helps the body shift into sleep at the end of the day. A part of the circadian rhythm, melatonin has an integral role in getting a full night’s sleep.

Our bodies naturally make melatonin. However, normal levels of melatonin decline as we get older. Melatonin can be made synthetically for supplements and is often used to treat jet lag, anxiety, and other sleeping issues. Supplements of this hormone are widely available over the counter in a variety of forms such as pills, liquids, and chewable tablets. Most people take melatonin without issue. However, some people report side effects of daytime sleepiness, headaches, and dizziness when supplementing melatonin.

Does Melatonin Expire?

All medications and supplements have an expiration date. Expiration dates do not necessarily mean that the medication or supplement is bad after that date. They are dated indicators from the manufacturers communicating when full potency can no longer be guaranteed. Many oral tablet supplements and medications have been found to be 90% effective up to five years after the expiration date. It is important to note, however, that certain medications should not be used past the expiration date.

The melatonin you purchase has an expiration date printed on the label. That does not mean that your melatonin stops working on that date. Storing your supplements in a cool, dry, dark place, like a cupboard, may potentially help extend the shelf life of your melatonin beyond its stated expiration date.


What Happens If You Take Expired Melatonin?

Medication and supplement manufacturers choose expiration dates to ensure that you are getting full potency by the printed date. These dates err on the side of caution. It is possible that your melatonin supplement maintains its shelf life and potency past the date printed on the label.

Melatonin is generally considered a safe and well-tolerated  supplement, even when studied for potential overdose risks. Considering the long shelf life of most supplements and the safety of melatonin, using expired melatonin may not be harmful. However, you might notice that expired melatonin doesn’t make you as tired or drowsy as unexpired melatonin. If this is the case, then your melatonin may be losing its potency and should be replaced.

How Long Does Melatonin Last in Your Body?

Melatonin is fast-acting, with a half-life of 20 to 40 minutes. The half-life of a medication or supplement measures how long it takes for half the dose to be processed and eliminated by the body.

Researchers found that after taking a normal dose of 1 to 5 milligrams, people’s melatonin levels were at their peak within an hour. In that same study, melatonin levels were back to normal after four to eight hours.

Taking an extended release melatonin pill may make you feel more tired when you wake up, especially if you are not able to get a full eight hours of sleep. Extended release pills may also take longer to help you fall asleep. Opting for an immediate release pill or chewable tablet may help you fall asleep faster and wake up feeling more refreshed.

When Should I Take Melatonin to Optimize Its Effects?

Melatonin is produced naturally by the pineal gland in the brain and helps the body shift from waking to sleeping. Taking melatonin between 30 minutes and two hours before bedtime is generally recommended.

You may want to try using melatonin every other night or a few times a week as needed. Any long-term use of melatonin should be discussed with a doctor or medical professional.

What Is the Proper Melatonin Dosage?

Typically, adults can take between 0.5 milligram to 5 milligrams of melatonin safely. Like any other supplement or drug, it is important to talk to your doctor first. If you choose to try melatonin, start with the lowest dose possible and slightly increase it if needed. It is best to avoid dosages over 10 milligrams, as you may experience unpleasant side effects such as headache and fatigue.

It should also be noted that melatonin is considered a supplement in the United States, and is not regulated by the Food and Drug Administration. Without strict regulations or guidelines, the amount of melatonin that a supplement contains may differ from the label. Inaccurate labeling of melatonin supplements is common.

If you are concerned about the potential side effects of melatonin, there are other over the counter sleep aids to consider. Diphenhydramine and doxylamine are two popular antihistamines that are also used to aid sleep. Herbs like valerian have also been shown to help promote sleep.

Finding the sleep aid that works for you may take time. Ensuring that you are engaging in healthy sleep hygiene practices may also help you get better sleep.

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About Our Editorial Team

Tom Ryan


Tom has over 10 years of copywriting and editorial experience across sectors such as technology, healthcare, education, and consulting.

John DeBanto

Internal Medicine Physician


Dr. DeBanto is a medical doctor and gastroenterologist with 20 years of experience in obesity management and related issues such as sleep apnea.


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