Does Metformin Go Bad

In this brief article, we will be discussing: does metformin go bad, along with its uses and dosage. We will also be highlighting how to safely store and dispose of medication that has gone bad. 

Does Metformin Go Bad?

The short answer would be no, but taking medication past its expiry date isn’t recommended.

This is because once a medicine expires, its components and active ingredients might start breaking down, making the drug less effective. Moreover, and rarely, certain drugs might change their chemical composition and turn toxic.

So, once a medication is past its expiration date, its effectiveness and safety cannot be guaranteed. 

Then What Do Expiration Dates Indicate?

Surprisingly, new research indicates that the expiration dates on drugs probably don’t mean what we think they do. After a law was passed in 1979, it became mandatory for drug manufacturers to state an expiration date on all medications. The pharmaceutical product shelf life, also referred to as the expiration date, is the time period during which the product is expected to retain its identity, purity, quality, and strength when properly stored as specified in the container label. Performance of the drug product beyond the manufacturer set shelf life has been a subject of study over the past several decades. Studies have shown that many drug products retain their shelf life quality characteristics such as potency and efficacy, several years beyond the expiration date if stored properly (2).

What this date means is that the manufacturer guarantees the full safety and potency of the drug up to that date, given that it is stored as instructed.

How To Store Medications To Maintain Quality?

Here are a few essential tips to follow if you want to retain the quality and effectiveness of your medications:

  • Keep prescription and over-the-counter medications away from heat and moisture.
  • Always store them in a cool and dry place such as a dresser drawer, kitchen cabinet, storage box, or closet shelf, unless otherwise instructed on its label. This will help the drugs remain safe and effective till their expiration date.
  • Avoid storing medicines in a bathroom cabinet. This is a high-temperature, high-moisture area and could cause the medicines to break down quicker than they normally would.
  • Do not store medicines near hot appliances or heat sources such as an oven, since this could also increase their rate of breakdown.
  • Certain medications may have different storage requirements. For instance, insulins and certain oral liquid antibiotics need to be stored in the refrigerator. Remember to always check the label, and consult your pharmacist if you have any doubts.

How Should You Dispose of Expired Medications?

Drugs are an essential factor when it comes to improving health issues related to human beings, but the proper disposal of unused or expired drugs is equally essential. Disposal of unused prescription drugs is a significant concern. The unused drugs should be destroyed utterly to eliminate the toxic effects on flora and fauna. The improper disposal of unused drugs could be the reason for the contamination of surface, ground and drinking water. Safe disposal methods as described by World Health Organization (WHO) are incinerations, inertization, returned to pharmacy or supplier, encapsulation, chemical decomposition (3). 

There are many ways of safely disposing of expired medication. While this is also mentioned on the label information of the medication, not all manufacturers include it.

As per the US Food and Drug Administration (FDA), the safest way to dispose of expired medication is at a drug take-back location. Many community pharmacies, health systems, and police departments provide ‘unused medication drop boxes’ for conveniently placing any medication that needs to be disposed of. ‘Take-back’ days are generally scheduled at the end of April and October. 

If you’re disposing of medication in the garbage, the FDA recommends that you mix it with some undesirable substance such as dirt, kitty litter, or used coffee grounds, seal it inside a bag, and then throw it in the trash. Also, don’t crush unused tablets or capsules prior to placing them in the bag.

Certain medications have a high-abuse potential, and can even cause death if accidentally taken. These medications are included in the FDA ‘flush list’, and need to be disposed of at home. And don’t worry, the FDA confirms that flushing medicines down the toilet is a much lesser environmental hazard than accidental consumption.  

What Is Metformin?

Metformin is classified as an oral hypoglycemic prescription drug that belongs to a category of medications known as biguanides. These medications are used to reduce blood sugar. 

Who Is Metformin Prescribed To?

Metformin is routinely prescribed to people with type 2 diabetes to control their blood glucose (blood sugar) levels. It is generally given when exercise, diet, and weight reduction regimes have failed to lower a person’s blood glucose significantly enough. 

Metformin has also been shown to be particularly useful in deferring complications associated with overweight people with diabetes.

Metformin is also usually recommended (off-label) for treating polycystic ovary syndrome (PCOS); however, this use isn’t currently FDA-approved. Metformin has few adverse side effects, the most common adverse side effects being gastrointestinal symptoms (incidence rate 20%–30%), including nausea and vomiting,6 and the most serious adverse effects being lactic acidosis (incidence rate 1/30,000), mainly in diabetic patients with liver and kidney dysfunction (1). 

With further exploration of the clinical effect and possible mechanism of metformin, its indications have been extended to antitumor effect, anti aging effect, cardiovascular protective effects and neuroprotective effects (1).

How Does Metformin Work?

Metformin acts by lowering the amount of glucose produced by the liver, and by facilitating the entry of glucose from the blood into body cells and tissues. It´s effects include the decreasing intestinal glucose absorption, improving peripheral glucose uptake, lowering fasting plasma insulin levels and increasing insulin sensitivity, which result in a reduction of blood glucose concentrations without causing overt hypoglycemia (1). 

How Should You Take Metformin?

The recommended adult dosage of metformin ranges from 500 milligrams three to four times a day, to 850 milligrams two to three times a day. 

The maximum daily dosage is 2,550 milligrams once a day. 

Tablets should preferably be taken with a mean meal to minimize the risk of gastric complications, including nausea, diarrhea, and vomiting.


In this brief article, we discussed: does metformin go bad, along with its uses and dosage, while also highlighting how to safely store and dispose of medication that has gone bad.

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


  1. Wang, Yi-Wei, et al. Metformin: a review of its potential indications. Drug design develop ther, 2017, 11, 2421.
  2. Khan, Saeed R., et al. United States Food and Drug Administration and Department of Defense Shelf‐Life Extension Program of Pharmaceutical Products: Progress and Promise. J Pharm Sci, 2014, 103, 1331-1336.
  3. Kaur, Harpreet, and Jashanpreet Singh. Safe disposal of medication practices. Plant Arch, 2020, 20, 2814-2819.