Researchers have recently discovered what many people with diabetes have known for years: The popular Type 2 diabetes drug metformin (brand names Glumetza, Riomet, Glucophage, Fortamet, and others) has a distinctive scent that, for some people, is enough to cause them to stop taking it. But as the most widely prescribed diabetes drug in the United States, metformin plays an important role in helping people with Type 2 diabetes control their blood glucose levels, and experts have suggested several solutions for dealing with the medicine’s unique scent.
In a letter published in the Annals of Internal Medicine, physicians from the Medical College of Georgia described two adult men with Type 2 diabetes who complained of a “dead fish” odor of metformin that had led both men to stop taking the medicine. Searching the medical literature for more information, author J. Russell May, PharmD, and colleagues found no reports of this issue. Upon searching the Internet, however, the researchers came across hundreds of message board posts referencing metformin’s odor, and an informal survey of pharmacists found that many could identify the medicine by its distinct smell.
May and his colleagues wrote to the journal to raise awareness of this issue and questioned whether nausea, one of the most commonly reported side effects of metformin, could in some cases in fact be a reaction the fishy odor. May noted that “Metformin is an excellent drug, but the immediate-release formulation may have an odor to it. The smell is fishy or like the inside of an inner tube, and in a patient’s mind…they may think the drug isn’t good.” (A manufacturer of metformin notes that there has been no association between the odor of metformin and its effectiveness.)
The authors indicated that switching to one of the extended-release versions of metformin, which have much less smell (if any), solved the issue for one of the men described in the letter. (The other man refused to try the extended-release version.) The researchers suggest that anyone with a concern about metformin’s scent should not stop taking the medicine but should speak with his physician about the possibility of switching to a different formulation. Another solution proposed by May is for people to hold their nose while taking the drug.
For more information about the doctors’ findings, read the article “‘Fishy Smell’ May Keep Patients From Diabetes Drug” or see an excerpt of the letter in the Annals of Internal Medicine. To learn more about metformin, click here.
Have you noticed an odor to your metformin? What, if anything, have you done about it? Let us know with a comment below!
I have had Glucophage (Brand Name), and noticed no smell. Since then, I have started purchasing generic Metformin from $4 list at Wal$Mart, and have got different “versions” from different manufacturers. One of these, (I don’t remember the mfg.) Smelled very bad, fishy. This was one where the pharmacy had put 3 months worth in one huge container, so I am assuming they had a large bulk container and had to count out the pills. My latest refill was from a manufacturer i had had before, and was pre-packaged by a month’s amount, so they only had to take the bottles off the shelf and put on a label. These do not have a noticably bad odor. But I have never have had any aftertaste from any that I have noticed… I am under the impression that generic versions of the drugs only have to have the active ingredient be the same, generic mfg’s can and will change the non-essentials, such as color, flavorings, filler, etc. Maybe this is only from a few mfg’s? Anyway, Stay on your Meds, everyone!!!
Posted by Randy | Feb 19, 2010 at 8:10 pmPart of what you have mentioned is correct. Some people do complain of “uneasy feeling” when it comes to metformin, when they get started on treatment. But later on, probably due to the upregulation of taste receptors or smell sensory receptors, they do not feel that uneasy feeling (reported in some as nausea, fishy odor, typical odor). So mostly the coninued use of metformin over the time has overcome the odor problem. Extended release version has been used not so frequently w.r.t. regular metformin. But this data is interesting to understand from the compliance point of view in diabetics.
Diabetes India: Promoting Healthy Diabetes Life
Posted by Diabetes India | Feb 19, 2010 at 11:11 pmhttp://diabetesindia.org
The extended release form smells bad, too. I get it down as quick as I can.
Posted by Deb | Feb 20, 2010 at 12:11 amI have been taking Metformin for about three years and am really getting sick and tired of the putrid aroma. Luckliy I found that the manufacturer Apotex made a generic without any smell! Too bad for me they have numerous recalls and the brand is no longer available at any pharmacy around me. Not only do these pills stink, they make me smell and make my perspiration stain white clothing. Nasty business. Can’t any of these scientists figure out the issue and work a solution to the stink?
Posted by James | Feb 23, 2010 at 9:43 amI have noticed the odor from the first time I started taking Metformin. I just swallow mine as quickly as possible and try not to breath as it is going down. I have written several times about it to different publications and manufacturer, but I guess nothing can be done. I’ll just continue taking it because I know it’s doing me good.
Posted by Peggy | Feb 24, 2010 at 1:24 pmHave been taking Met for 5 years and have noted the fishy smell. Just ignore it and have had no adverse reaction and tupe 2 is completely under control
Posted by Ed | Feb 24, 2010 at 1:25 pmI took Metformin for several years, having the prescription filled monthly. Then with a change of physicians, the prescription was filled with a three month supply. That is when I noticed the putrid smell coming from the pills. It wasn’t fish, it smelled like an unclean urinal. The urine smell was overpowering. I am so glad to be off Metformin and on to other medications.
Posted by DeDe | Feb 24, 2010 at 1:41 pmA more important issue questionably not being covered: in June 2009, the American Diabetes Association reported at their annual conference in New Orleans that 75% of patients on metformin develop peripheral neuropathy within the 12 months of starting metformin. Why isn’t there more coverage on this issue? I developed “PAINFUL” peripheral neuropathy 3-4 months after starting metformin. I took my self off the medicine, and the pain has subsided. But the damage by metformin is done. Why hasn’t this “association” provided more public awareness?
Posted by Henry Mendoza | Feb 24, 2010 at 2:13 pmI take Metformin and my complaint is after I take it I notice this bad smell in my urine. Hard to miss the odor–its strong! I take the pill with my morning oatmeal so I don’t have any trouble getting them down but sure notice the odor when I open a new pill container from the drugstore. Since it smells like the odor in the bathroom–voila! I am pretty sure its the Metformin.
Posted by Doris | Feb 24, 2010 at 2:24 pmYES I AGREE WITH THEM. I STOPPED TAKING MEDIFORMIN BEC I HAD DIRAHHA FOR THREE MONTHS AND I FETL WEAK AND DID NOT FEEL LIKE TO GO OUT ANYPLACE BEC I MUST NEAR BATHROOM. SO CHANGE TO GLUCOPHAGE. I FEEL MUCH BETTER, NO MORE DIREHHA. BUT I NOTICED GLUCOPHAGE IS REAL EXPENSIVE. DO YOU KNOW ANY WHICH IS BETTER THAN GLUCOPAHAGE. HELP ME
Posted by ELLEN KONOSKI | Feb 24, 2010 at 2:45 pmI have notice the smell recently when i open the bottle it’s bad , i take what am going to use and lay it down for a minute before i take it, then i take it and there no smell going down.
Posted by maria alvarez | Feb 24, 2010 at 3:11 pmI HAVE BEEN USING MET FOR YEARS AND NOTICED THE SMELL WHEN I OPENED THE BOTTLE, PUTTING THE CAP ON RIGHT AWAY THE SMELL ISN’T SO BAD. GETTING IT FROM A DIFFERENT MANUFATURER THE SMELL ISN’T THERE. DEPENDS ON THE PHARMACIST WHO THEY ORDER FROM.
Posted by JOE | Feb 24, 2010 at 5:06 pmHaving Type 2, I take metformin. I have noticed the odor for years. To me it has a chemical odor.
Posted by Don | Feb 24, 2010 at 5:28 pmFresh fish has a much different oder.
Once when I picked up my generic order they had filled the bottle with pills that had the aroma
of alomonds or hazelnuts. Only got those once in ten years. Really did make a difference when it came to taking them. So something can be done
about the aroma, if the big drug companies cared.
Close the bottle quickly. it leaves the odor in the bottle I have been taking it for over 4 years, with excellent results. I can tolerate the odor, because it has been keeping my blood sugar under control, and preventing the use of insulin.
Posted by Wayne | Feb 24, 2010 at 7:30 pmI have taken metformin for 3 years and have never once noticed any odor. It keeps my numbers where they should be.
Posted by Sharey Travis | Feb 24, 2010 at 7:32 pmI have been taking metformin for over a year and have never noticed any odor. I just now checked my bottle to make sure and had my husband sniff it as well and niether one of us noticed any odor. If it makes any difference, I get mine filled at Walgreens. I wish good luck to those who are having problems, but so far all is well in my medicine cabinet.
Posted by Jeanette Simms | Feb 25, 2010 at 2:46 pmI have been taking metformin for 4 years. Last summer had my perscription refilled and the pills had a very, very fishy odor. Not only that, but I could hardly swallow them the smell was so bad. My skin was also really itchy and my stomach was always upset. Had to get a special lotion from my doctor for my skin. I took the pills back to the pharmacy, told them of my problem and they said that all metformin had a fishy odor; nothing was accomplished. So I called the pharmacutical company and they called my pharmacy and found out that this was the first time I was given this brand (same company, different brand) The old brand,which is pre-packaged, was ordered and it is odor free. Problem solved! So there is an odor free brand.
Posted by Dianne Lapolla | Feb 25, 2010 at 6:02 pmYes, I have been smelling the fishy metformin for several years now. Why does it smell fishy and what can be done about it. I just can’t believe that these pills leave the lab smelling like fish. I can’t stop taking them b/c they smell this way, but b/c there are no alternatives.
Posted by Felecia | Feb 26, 2010 at 8:17 amI’ve been taking this drug for 6 years and I do not smell anything at all!!
Posted by di hal | Mar 03, 2010 at 1:09 pmI have been taking Met for almost 3 years and haven’t noticed the odor. I, like Jeanette, get mine filled at Walgreen’s. However, I have noticed a number of bouts of stomach distress!
Posted by Allen | Mar 03, 2010 at 1:29 pmMy problem is metaformin results vary from batch to batch. Some knock down fasting sugar and some do not, Other times,diarrea, sometimes not.
Urine oder varies from batch to batch as well. I thought it was my BP meds, but now i think it was the metaformin.
Started taking one gram of chromium picolinate, prior to one a day insulin. With this current batch of metaformim, my fasting sugar is 35 points lower.
Having tried it with daytime use (with metaforin)I found severe drops of as high as 75 points from fast sugar.
I do not think it wise to try chrome without testing blood 3-4 times a day. hypoglycimic (low sugar) reaction appears possible.
Posted by William | Mar 03, 2010 at 1:41 pmI take Metformin ER and have not noticed any fishy smell or odors from it. I do get mine from Walmart
Posted by gayle | Mar 03, 2010 at 2:03 pmAll I know is that my cat comes running over and is intently interested in my metaformin pills. That is when I first equated the smell with fish. Never bothered me but it sure has the cat’s attention.
Posted by Jeff | Mar 03, 2010 at 2:15 pmI began taking metformin a year ago. I noticed the “fishy” smell, but it did not bother me.
I also track my fasting blood sugar every morning.
After about 6 months, I began to notice that some bottles of metformin (Sandoz from WalMart) had a greater smell and others had none.
Then I noticed that my sugar levels were down when taking the more smelly pills and sugars levels were higher when taking those without smell.
I even returned a half full bottle of no smell to the pharmacist for some that smelled and my sugar levels dropped 15-20 points on average.
For me, the worse smell the better!
Posted by Bill | Mar 03, 2010 at 2:42 pmI have taken this drug for years, and I have never noticed a smell.
Posted by Kathy Force | Mar 03, 2010 at 3:21 pmI first noticed the fishy smell when i started the drug 4 yrs ago. I googled it and other’s were experiencing the same oder. The issue for me was not the oder as much as a few yrs later the depletion of B12 in the body that Metformin can cause. I experienced sore swollen tongue. Did some online reserach, spoke to my Dr and started taking B12 orally. Luckly my Dr knew about this side effect. Some Dr’s do not.
Posted by Lisa | Mar 03, 2010 at 4:46 pmthis med causes me to feel very tired and causes a large amt of explosive gas in my digestive tract. also lots of bloating. sometimes i take it and it helps, sometimes, it dosen’t make the blood sugar go down.
Posted by cozetta fields | Mar 03, 2010 at 4:53 pmPeripheral Neuropathy caused by Metformin was discussed in a recent article I found on the Google home page. The article claimed that metformin causes a B12 deficiency which in turn causes peripheral neuropathy. It said to have your doctor run a serum B12 test to determine if you have a deficiency. You can request that your doctor give you a B12 shot or you can get B12 supplements.
Posted by Debbie | Mar 03, 2010 at 4:58 pmYes, I have noticed. The pharmacist said he could not smell anything, but replaced the Rx. The replacement had the same problem I had never heard of this, but it has been a problem for me only in the last few months. The first thought was that the medication had deteriorated. Perhaps some people cannot smell it? It is not always present.
Posted by BA | Mar 03, 2010 at 5:49 pmI’ve been taking Metformin (1,000 mg 2 x day) since I was diagnosed over 2 years ago.
I originally got 30 day scripts from Walgreens, then started 90 day mail order supply through my insurance. Now I get a 90 day supply at K-Mart for $10.00.
There have been multiple manufacturers over that time. One time my script was filled with pills from 2 different manufacturers. I have never noticed ANY smell from any of the pills.
The drug works great for me - with no complications. This is the first time that I was even made aware of any issues other than some people who have digestive problems when taking Metformin.
Posted by phil | Mar 03, 2010 at 9:17 pmYes, it does have a fishey oder.
Posted by David Dallas-Midgley | Mar 04, 2010 at 12:48 amI too have had batches that smelled like a heavily used catbox. And I’ve had some that had no odor at all.
The most recent bottles are from Medco out of Dallas but filled in Juarez, MX. They are quite toxic.
What I do is put a moisture packet in the bottle and the smell is reduced considerably.
Posted by Mike | Mar 04, 2010 at 2:14 amYes, the smell is terrible. I had been taking the extened release and my doctor wrote my prescription for the regular metformin. When I got my medicine, I thought I must have the wrong medicine. I called the drug store to check and was informed that the prescription had been written that way. I checked with my doctor and he advised he would change it or I could contine taking as written. I thought I could stand it for 3 months but I was so glad when my 3 months was up.
It smelled like fish, but maybe really bad fish. Now I can hardly stand to pass the fish at the grocery. I held my breath when I swallowed mine. I’m back to ER, thank goodness.
Posted by Wanda Pulliam | Mar 04, 2010 at 2:45 amI take metformin 2 times a day, 1000 mg, both times. Even on smaller doses the fish smell is pervading. It cause my urine to have a fish smell that is quite strong and I hate it. I don’t know why the FDA would every deny or ignore what all of us taking this medication know. It smells like fish in a big way!!!
Posted by Bill Knapp, RN | Mar 04, 2010 at 3:06 amI have been using Metformin for years and have never experienced a “Fishey Smell”
Posted by Jarrett Anderson | Mar 04, 2010 at 8:45 amI’ve been taking metformin for almost a year and never smelled any type of fishy smell. It doesn’t upset my stomach either. I take it with food like it recommends. I purchase the $4 metformin from Wal-mart and always get the same company and no problems. Why can’t they put a coating on the pills like some other medications do? That should help with the smell that some claim to smell and it would make it easier to swallow too.
Posted by Elizabeth Arsenault | Mar 04, 2010 at 11:15 amI’ve taken Metformin for at least 6 years and yes, there is a horrible odor. What I finally found is that I now put my pills out in a 7 day container/pill box and that seems to help get some of the odor out at least for swallowing/getting it past my nose. I do notice an odor in my urine but that seems to happen with most medications and/or supplements. I drink at least 60 oz of water a day which seems to help a little with that too.
Posted by Pat Davis | Mar 04, 2010 at 11:36 amMetformin smells fishy for sure. I just place the pills on the table for a while than i take them.
Posted by Robert l Pann | Mar 04, 2010 at 1:11 pmHow embarrassing to stand at a urinal (ball park, or some other public facilities) and note others nearby almost puke at the smell eminating from my urinal. If I do not take my 1000mg twice a day during a meal, I often have bad cases of diarrhea. I’ve always accepted these frustrations as part of being diabetic. I’m heading to my doctor for a change soon!!
Posted by Robert Bryant | Mar 04, 2010 at 10:01 pmI noticed the fishy odor upon switching to the Metformin generic formula. I take 2 tablets a day, so the odor from the 90 day supply is quite strong.
Posted by R Lauterbach | Mar 05, 2010 at 11:50 amTo help avoid the unpleasantness of the odor, I purchased a monthly pill organizer. I put 2 tablets in each section, I then have to open the 90 day supply bottle only once a month. I make sure I fill the organizer hours before having to take a dose. On a daily basis, I do not notice the fishy smell at all.
Have been taking Metformin for 5 years in the 500 mg pill, 3 times a day, with food. Have been getting it from Humana/Right Source 3-month by mail and Walmart Louisville, Ky and Clearwater, Fla. No smell, no problems, no complaints, good results, no change.
Posted by Jayne Black | Mar 06, 2010 at 8:43 pmMetformin most definitely has a strong fishy odor, esp. the generic versions. I have been taking it for 1 year. A client reported that her OB/GYN prescribed Metformin for increase fertility and to regulate her menstrual cycle.Check out the side effects of this drug. It has really decreased my glucose levels while increasing my libido also. FDA needs to investigate.
Posted by Harriet J Seabrook RN | Mar 08, 2010 at 8:11 pmSince I started taking Metformin 4 years ago, I have had trouble will my leg and sometimes my arm aching like a toothache. I told the doctor’s assistant and she told me to see a muscle specialist. I will be requesting to see the doctor when I go in May to see if I have vitamin B12 deficiency. Also, the pharmacist change the manufacturer and the Metformin does not smell but it seems not to control my blood sugar as the other brand does.
Posted by Margaret Wade | Mar 13, 2010 at 12:53 amThe past year the metformin I get does smell like innertube or fishy. I take it out of the bottle it came and use something else. I still take it, but do not like the smell. I get mine from the VA.
Posted by Gil stallknecht | Mar 14, 2010 at 10:08 pmi take 4 of those suckers a day,, 2 in the am, and 2 in the pm,,
Posted by Judy - northwest PA | Mar 15, 2010 at 2:27 amthe last few months i have gotten them at giant eagle,, the smell is nauseating,, and i dread everytime i need to take them.
i don’t know what to do,, it is so hard for me to take them. i don’t know if i call the pharmacys and ask them to smell the bottle before i get my refill, i will try leaving them set out for awhile before i take them,, it’s worth a try.
Henry Mendoza.
Posted by Ruby M | Mar 16, 2010 at 6:27 pmPlease provide your source/article/magazine for Feb. 24, 2010 comment regarding Metformin and peripheral neuropathy announcement at ADA annual conference. I am about to begin taking Metformin and would like to have the info to back up my disucssion with my physician. Thank you.
Yes, Yes, Yes. there is definately a dead fish, fishy smell to metforme. I had to hold my breath when I opened the bottle. Thank goodness my doctor took me off of it. I’m trying to controled my blood sugar with diet, so far so good.
Posted by keysona | Mar 20, 2010 at 10:26 amI have also been taking metr for like 10 years, I got started smelling the odor just this last 3 years. I have not been taking they like I should and my blood suger are HIGH in the 405mg. Not good at all.
Posted by Anita | Mar 30, 2010 at 11:23 amI knew I smelled something! My husband always says I “breathe too deeply”….but a few others do too. Metformin does smell strongly, I’m off it now, thank heavens.
Posted by VJ Cordova | Mar 31, 2010 at 3:25 pmI’ve noticed the smell but the smell doesn’t upset me in anyway but I often wonder what it is made of to be so effective in helping the diabetes.Just what is it made of to smell the way it does.
Posted by Ivernia Schwartz | Apr 05, 2010 at 10:24 pmI can’t take many other medicines without an allergic reaction but this doesn’t bother me so take it even though it has a smell.
I was overwhelmed by the smell of this medicine, as well. So, my doctor switched me to the ER version…and voila’! No more odor!
Posted by Pam | May 11, 2010 at 8:40 pmI’ve been on metformin for a few years now, but only noticed the smell recently. It’s not noticeable when I open a new bottle, but is present within a few days. Considering some of the issues I’ve had with blood pressure meds, a fishy smell isn’t much to contend with. I’m just happy the stuff works.
Posted by Larry | May 11, 2010 at 9:27 pmmetformin has always smelled like fish or inner tube smell no big deal just swallow and it’s all gone
Posted by Marty K | May 12, 2010 at 5:54 pmI have not noticed a smell, but have to wonder if there’s more to it than that. I have always hated fish and this medicine is tearing up my stomach.
Posted by Vicki | May 18, 2010 at 3:36 pmI have celiac disease among several others. Along with many other medications I take I recently started metformin (in the beginning of shingles for the third time)….not exactly great timing but then again when is good timing?
All medications have their share of side effects but the real question is whether or not it is helping in your condition. I try and wait a while before stopping a new drug. Having major gastrointestinal problems with very damaged intestines I can’t tell anymore if it’s medication, a virus, or just my body and how it does not function properly. As for the fish smell I’m not sure. I just the medication and hope it will work in some positive way. It’s too tiring being sick all the time.
I don’t know if any of this helps but I am a 37 year old single parent of a child with Tourette’s so we have our fair share of hard times so I just try and stay thankful we have some type of medical insurance and keep up with our doctors often.
~Best wishes to all of you
Posted by Kj | Jun 01, 2010 at 7:44 amYes. Mine (Teva) has a very bad smell when opening the plastic bottle. I stopped taking them yesterday until I did some research — I took one this AM. I am not sure but it might be causing some degree of back pain also — on the left side just under the ribs. Bill
Posted by bill | Jun 30, 2010 at 7:41 pmThe first two prescriptions I had filled had no odor at all - the last batch smells PUTRID - but I don’t taste it because I swallow all pills quickly (put water in my mouth, hold it there, add pill, swallow, more water). HOWEVER I am so relieved to read here about the STINKY URINE. This is a new development and I can’t get in to see my family doctor for a month. I thought my kidneys were rotting away or something - relieved INDEED for this info. THANKS!!!
Posted by Mimi Malone | Aug 07, 2010 at 12:27 amI too find metformin smells unpleasantly fishy and lately my urine has a disgusting odor. Thanks to the people who who have contributed to this discussion. My next discussion is with my doctor.
Posted by James | Aug 30, 2010 at 1:28 am