Does Melatonin Go Bad

In this brief article, we will be discussing: does melatonin go bad, how to store it and what are the risks of ingesting expired melatonin. Melatonin is a hormone used in the treatment of sleep disorders. 

Does Melatonin Go Bad?

Yes, Melatonin goes bad, as any other chemical compound. Melatonin and other medications or supplements lose their potency during time and increased storage. In addition to having a decrease in the expected effect of the drug, expired melatonin can degrade and generate other compounds, which can have negative effects on health. 

It is known that medications degrade over time, particularly with exposure to light, oxygen, or humidity; poor storage conditions will accelerate their degradation (2).

What determines the shelf life of Melatonin?

The shelf life of Melatonin depends on the form in which it is presented. Commercial forms of Melatonin available on the market are an immediate-release form of a fixed dosage of the hormone and a modified release tablet that provides prolonged and slowed release of the drug (6). 

Drugs are usually formulated containing excipients, which are inactive compounds that are used to facilitate the manipulation and ingestion of the medication. These excipients play an important role defining the shelf life of the drug, as they may undergo chemical reactions during storage and affect the main pharmaceutical ingredient (3). Therefore, it is important to look for the expiration date printed on the packaging. Different brands of the same medication have different shelf lives, as they have different formulations.

What is the shelf life of Melatonin?

Melatonin in hard capsules has a shelf life of 18 months at 25 °C and low humidity (60% RH) and away from light (1). Melatonin in the slowed release form has a shelf life of 3 years (7).

In a study, melatonin supplements in the form of tablets that were stored for 11 months beyond the manufacturer’s expiration date were analyzed. The results showed that there was a significant decrease of the expected effect. The supplements were found to contain the active pharmaceutical ingredient at 89.2% of the label claim of 10 mg per tablet. In addition, some products resulting from the degradation of melatonin were identified (2). 

How to identify if Melatonin has gone bad?

To identify that Melatonin has gone bad, it is necessary to be aware of signs of changes on the properties of the drug, such as color, odor and nature (texture, hardness) (3). 

 What Happens If You Use Expired Melatonin?

In addition to not having the expected effects of Melatonin, if you use expired melatonin, it is possible that you experience negative effects due to the ingestion of compounds generated from its degradation. 

In addition, the degraded drug can cause unforeseen and unwanted side effects due to the effect of possible toxic compounds generated. Patients with serious and life-threatening illnesses can be particularly vulnerable to potential hazards from drugs that have undergone degradation (4). 

How to properly store Melatonin?

To properly store Melatonin, it is necessary to avoid moisture and exposure to heat and sunlight. Here are a few essential tips to follow if you want to retain the quality and effectiveness of Melatonin (5):

  • Melatonin should be stored in a location with humidity no more than 60%, which means that the bathroom and kitchen were inappropriate places for it.
  • Store Melatonin at temperatures between 15°C to 30°C (59°F to 86°F).
  • Garages may undergo constant temperature changes that would be unsuitable for the storage of Melatonin.
  • Store Melatonin in places safe from light and heat.
  • Keep Melatonin in places that are safe from the access of children.


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. Wotring, Virginia E. Chemical potency and degradation products of medications stored over 550 earth days at the international space station. AAPS j, 2018, 18, 210-216.  
  3. Swaroop, A. Prem, and D. Varun. A glimpse on expiry date of pharmaceutical dosage forms. Pharmanest Int J Adv Pharmaceut Sci, 2011, 2, 423-33.
  4. Expiration dates – Questions and answers. United States Food and Drug Administration.
  5. Funk, Olivia G., et al. Medication storage appropriateness in US households. Innov Pharma, 2021, 12. 
  6. Musazzi, Umberto M., et al. A new melatonin oral delivery platform based on orodispersible films containing solid lipid microparticles. Int j pharmaceut, 2019, 559, 280-288.
  7. Circadin. Healthdirect. Australian Government Department of health.