Does Something Smell Fishy? It Could Be Your Metformin

| Mar 4, 2010

If you regularly take metformin, one of the oldest and most respected tools in doctors' anti-diabetes kits, chances are that you don't detect the unpleasant odor that turns some type 2s against the drug.  Some think it has fishy smell, while others say that it reminds them of the inside of an inner tube.

It's usually metformin's immediate-release formulation that has the off-putting smells, according to a Georgia professor who described the phenomenon in the February 16 issue of the Annals of Internal Medicine. In his letter, J. Russell May, a clinical professor at the University of Georgia College of Pharmacy at the Medical College of Georgia, said that he and his colleagues began wondering about the issue when two type 2 men under their care began complaining about the "dead fish" smell of the quick-release version of metformin. The smell was off-putting enough that both men stopped taking metformin. One of the men later began taking extended-release metformin and reported no smell. The other declined to take the extended-release version.

The men's reaction spurred May and his colleagues to search through medical literature for reports about metformin's smell. Although they found nothing in the literature, they did find hundreds of references to the drug's smell on message boards. When they queried pharmacists, some reported that they could identify metformin by an odor that they compared to "old locker-room sweat socks."

May and his colleagues acknowledge that their look into metformin's smell doesn't constitute major or formal research. But May raised the question of whether the nausea that is a commonly reported side effect of metformin may come from a perception of its odor rather than from the drug itself as it is ingested.

In reporting on the Georgia inquiry, HealthDay checked with Bristol-Myers Squibb, which is one of several manufacturers of metformin. A spokesman there told the publication that although "inherent characteristics" of metformin may produce a mild odor when users open a bottle of it, "there has been no correlation between an odor and the efficacy of metformin," which has been on the U.S. market since 1995. 

May recommends that type 2 patients who smell a metformin odor tell their doctor, lest they mistakenly assume that there is something inherently nauseating about the drug. In most cases, May surmises, a simple change in formulation should eliminate the disturbing odor. Otherwise, he advises, maybe users should just hold their noses and swallow fast.

Click Here To View Or Post Comments

Categories: Diabetes, Diabetes, Medications, Metformin, Type 2 Issues

Take the Diabetes Health Pump Survey
See What's Inside
Read this FREE issue now
For healthcare professionals only
  • 12th Annual Product Reference Guide
  • Insulin Syringe Chart
  • Insulin Pen Needles Chart
  • Fast-Acting Glucose
  • Sharps Disposal
  • Blood Glucose Meters Chart
  • Insulin Pumps Chart
See the entire table of contents here!

You can view the current or previous issues of Diabetes Health online, in their entirety, anytime you want.
Click Here To View

See if you qualify for our free healthcare professional magazines. Click here to start your application for Pre-Diabetes Health, Diabetes Health Pharmacist and Diabetes Health Professional.

Learn More About the Professional Subscription

Free Diabetes Health e-Newsletter

Top Rated
Print | Email | Share | Comments (9)

You May Also Be Interested In...


Posted by Nick Thompson on 4 March 2010

I think the professional response to the worries about metformin odor is completely inadequate. The human sense of smell is an extra-ordinary instrument for the detection of chemical composition and if it smells bad, there must be SOMETHING about the formulation making that odor. If the company cannot tell us what that is, then the product should be withdrawn. You wouldnt drink milk that smelled like fish, so why take metformin that smells like fish? Not clear why everybody is so casual about this.

Posted by PearlsGirl on 5 March 2010

I don't think my metformin smells like fish, I think it smells like pee.(yuck) I will be asking my doctor to make a change in my medication.

Posted by Anonymous on 5 March 2010

I have been taking Metformin for several years, and although I have noticed the bad smell from the beginning (and still do, to me it kind of smells like stale urine), it doesn't bother me. The smell is not so overpowering that I can't take the pill and I have not had the nausea associated with taking Metformin. To refuse to take it because of the smell when it might be the best thing for you medically, is ludicris. It's your health! There have been other documented benefits to taking Metformin and I am glad I can control my diabetes with the help of this medicine. My husband is a Chemistry major, and I have been in the labs with him, some of these things just have a bad odor to them, you can't get around that without altering the chemical, which would defeat the purpose.

Posted by Anonymous on 5 March 2010

my metformin makes my breath taste like tin, wet old tin. i always keep gum around and as long as i chew the gum i am ok, but some places you cannot chew gum.

Posted by crafty2003 on 6 March 2010

I take Metformin and yes it smells like fish only if you make on purpose to put it up to your nose and take a whiff. I've been taking it for many years and it doesn't have a taste to it. Just take it and swallow. If its going to help keep you alive, its well worth it. Whatever is in the metformin to make it smell like fish, metformin works to help control the blood sugars.

Posted by Anonymous on 9 March 2010

For goodgrief sakes, I have been taking this for years myself, and the only time that I smell something unpleasant is when I open the bottle and take a wiff. With all the new formulations of the same thing it is rather comforting to be able to open the bottle, take a wiff, and know that this is my metformen. Like someone said it's keeping us insulin stinks too but I'm not gonna stop taking it because of the smell.

Posted by Anonymous on 28 April 2010

I believe however that a company named Generex biotechnology corporation is developing a Metformin gum. This should help to alleviate some of the smell typically associated with the medicine and also make it so it can be very good to take, flavors such as mint for example are possible. They just recently reported that they had achieved bio-equivalence of the medicine and are going to sumbit a form to ask for the FDA's approval of the product. Any thoughts?

Posted by Nick Thompson on 4 May 2010

Look, I can suck it up and eat pills that smell like dead fish with the best of you. But I would rather be a wimp than the victim of some stupid industrial accident.

The point is that the human sense of smell exists, in part, to detect toxins. That something smells bad is prima facie evidence that there is something toxic in it. That the chemical company cannot tell us what harmless substance is generating the odor suggests that they are incompetent or afraid of losing their gravy train. In neither case am I happy with continuing to take their drug.

Posted by Anonymous on 23 January 2011

Taken it for years. Just this last batch smells bad... Change of manufactures?

Add your comments about this article below. You can add comments as a registered user or anonymously. If you choose to post anonymously your comments will be sent to our moderator for approval before they appear on this page. If you choose to post as a registered user your comments will appear instantly.

When voicing your views via the comment feature, please respect the Diabetes Health community by refraining from comments that could be considered offensive to other people. Diabetes Health reserves the right to remove comments when necessary to maintain the cordial voice of the diabetes community.

For your privacy and protection, we ask that you do not include personal details such as address or telephone number in any comments posted.

Don't have your Diabetes Health Username? Register now and add your comments to all our content.

Have Your Say...

Username: Password:
©1991-2015 Diabetes Health | Home | Privacy | Press | Advertising | Help | Contact Us | Donate | Sitemap

Diabetes Health Medical Disclaimer

The information on this site is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment. All content, including text, graphics, images, and information, contained on or available through this website is for general information purposes only. Opinions expressed here are the opinions of writers, contributors, and commentators, and are not necessarily those of Diabetes Health. Never disregard professional medical advice or delay seeking medical treatment because of something you have read on or accessed through this website.