Does Melatonin Go Bad

In this brief article, we will be discussing: does melatonin go bad, its uses and benefits, the correct dosage, potential side effects, and alternatives. 

Does Melatonin Go Bad?

Melatonin has an expiration date printed on the label of its bottle. However, this doesn’t imply that the melatonin stops working past that date. Melatonin in hard capsules is stable for 18 months at 25 °C and low humidity (60% RH) and away from light (1). 

However, you might feel that expired melatonin won’t have the same effects as unexpired melatonin, i.e. it won’t make you feel as tired or drowsy.

Nevertheless, storing supplements in a cool, dark, and dry environment such as a cupboard can significantly help enhance their shelf-life beyond the printed expiration date.

What is Melatonin?

Melatonin is a naturally occurring hormone that aids our body’s shift into sleep. It is manufactured primarily by the pineal gland present within the brain and is released as a result of darkness while being suppressed by light. It also has anti-inflammatory, antioxidant and anti-coagulopathic (is the process of hindering the clotting of blood) properties in addition to its endothelial (The main type of cell found in the inside lining of blood vessels, lymph vessels, and the heart) protective effects. Melatonin is produced from serotonin, which is made from tryptophan, an amino-acid found in many foods, including milk, eggs and nuts (2).

Melatonin is an integral part of our body’s intrinsic circadian rhythm which plays a vital role in maintaining our sleep-wake cycles and helps achieve a full night’s sleep. It synchronizes central but also peripheral oscillators (fetal adrenal gland, pancreas, liver, kidney, heart, lung, fat, gut, etc.), allowing temporal organization of biological functions through circadian rhythms (24-hour cycles) in relation to periodic  environmental changes and therefore adaptation of the individual to his/her internal and external environment (3).

What Are Melatonin Supplements Used For?

Even though our bodies naturally produce melatonin, optimal levels generally decline with age. This is where melatonin supplements come in handy. Up to about 70 million Americans suffer from chronic sleep problems, which are generally associated with obesity, diabetes, hypertension and increased cardiovascular risk (2).

Synthetically–prepared melatonin supplements are used to treat anxiety, jet lag, and issues relating to sleep disturbances. These supplements are widely available over-the-counter in the form of pills, syrups, and chewable tablets, and the majority of people report no side effects. Supplements of melatonin are prescribed to people with deficient production of this hormone and to treat reducing sleep disturbances in children with atypical development, such as autism (1).

What Happens If You Use Expired Melatonin?

Melatonin, a generally safe and well-tolerated supplement, has a considerably longer shelf life, so using expired melatonin might not have any harmful effects. However, as mentioned earlier, the effects might not be as pronounced, in which case it is better to replace the supplement with a fresh one. 

Supplement manufacturers mention expiration dates to make sure that you receive the full potency of the supplement by its printed date. It is just a cautionary reminder to consume the supplement within a given time frame. 

What Is the Proper Dosage of Melatonin?

Generally, adults can safely consume between 0.5 to 6 milligrams of melatonin per day. The drugs administered orally are made available as capsules at three different doses of 0.5 mg, 2 mg and 6 mg. This oral dosage form permitted a quick dispensation for hospitalized and ambulatory patients (1). But as with any drug or supplement, it is extremely important to consult your healthcare physician before including any such product into your daily routine.  

If you want to try melatonin to help with sleep, begin at the lowest possible dosage, and gradually increase if needed.

How Long Does Melatonin Stay in the Body?

Melatonin synthesis and secretion is enhanced by darkness and inhibited by light. Luminous information is transmitted from the retina to pineal gland through the suprachiasmatic nucleus of the hypothalamus. In humans, its secretion starts soon after sundown, reaches a peak in the middle of the night (between 2 and 4 in the morning) and decreases gradually during the second half of the night (4).

When orally administered, Mmelatonin provides quick relief and is fast-acting. It has a half-life of 20 to 40 minutes, which represents the time taken for half the dose of the supplement to be processed and cleared from the body.

Studies have shown that after consuming a normal dosage of one to five milligrams, melatonin levels reached their peak within an hour and returned back to normal after four to eight hours (4).


What Happens If You Take Too Much Melatonin?

Taking large quantities of melatonin can actually result in rebound insomnia. This can render the supplement ineffective or further exacerbate sleep disturbances. Avoid doses of more than 10 milligrams, since these may result in unpleasant side effects including fatigue, loss of sleep, and headache.  Some of the potential harmful effects of exogenous melatonin therapy include immunomodulatory effects which confers the risk of worsening certain rheumatologic conditions such as rheumatoid arthritis. It might also result in amenorrhea when used in large doses (2).

Always remember to take only small doses of melatonin supplements to promote and maintain your natural sleep cycle. 


Does Long-term Use of Melatonin Have Side Effects?

Even though the short-term use of melatonin in adults doesn’t generally cause any side effects, consuming large quantities for extended periods can cause bad dreams and grogginess.

Moreover, long-term use of melatonin can make certain drugs less effective, such as hypertension medication and birth control pills. However, a study concluded that melatonin supplementation therapy exerts a positive effect on psychosomatic symptoms in postmenopausal women and can be recommended as the useful adjuvant therapeutic option in treatment of these disorders (6).

Who Should Not Use Melatonin?

Melatonin can aggravate symptoms of depression, increase blood pressure in people taking hypertension medication, and may increase the risk of seizures.


Are There Any Alternatives to Melatonin?

For those concerned with side effects of melatonin, or those on medications that interfere with melatonin, there are alternatives to help them sleep.

Doxylamine and diphenhydramine are among the popular antihistamines used to facilitate sleep. Moreover, herbs such as valerian have also been shown to promote sleep. Other examples are hops, chamomile, and passionflower (5).


In this brief article, we discussed does melatonin go bad, its uses and benefits, the correct dosage, potential side effects, and alternatives. 

If you have any more questions or comments please let us know. 


  1. Filali, Samira, et al. Formulation, stability testing, and analytical characterization of melatonin-based preparation for clinical trial. J pharmaceut anal, 2017, 7, 237-243.
  2. Masters, Alina, et al. Melatonin, the hormone of darkness: from sleep promotion to ebola treatment. Brain dis ther, 2014, 4.
  3. Rajaratnam, Shantha MW, et al. Melatonin advances the circadian timing of EEG sleep and directly facilitates sleep without altering its duration in extended sleep opportunities in humans. J physiol, 2004, 561, 339-351.
  4. Morin, Charles M., et al. Valerian-hops combination and diphenhydramine for treating insomnia: a randomized placebo-controlled clinical trial. Sleep, 2005, 28, 1465-1471.
  5. Tordjman, Sylvie, et al. Melatonin: pharmacology, functions and therapeutic benefits. Curr neuropharmacol, 2017, 15, 434-443.
  6. Chojnacki, C., et al. The effect of long-term melatonin supplementation on psychosomatic disorders in postmenopausal women. J Physiol Pharmacol, 2018, 69.

Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.