Skip to main content

Why does Metformin smell like fish?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on May 10, 2023.

Official answer

by Drugs.com

Pharmacists and patients are well aware that metformin may come with a fishy smell when you open the bottle. The smell does not mean the drug is spoiled, it's just due to it's inherent chemical characteristics.

Metformin (brand names: Glumetza, Riomet, Riomet ER) is associated with relatively few side effects, but nausea may be one of them, possibly due to this 'fishy' odor. Many patients may not be able to tolerate this medicine due to the odor.

According to a report published in the Annals of Internal Medicine, some extended-release, film-coated forms of metformin have a lower odor, and may be less likely to cause nausea. If you can't tolerate your metformin, let your doctor know. A switch to the extended-release form or a different manufacturer may do the trick.

Metformin is a widely prescribed medication for the initial treatment of type 2 diabetes, and may even be used in prediabetes. Don't stop treatment on your own, always consults with your doctor.

Related: Metformin side effects (in more detail)

References

Read next

How long does metformin take to work?

Metformin will usually start lowering your blood sugar (glucose) levels in the first week of treatment, but it may take 2 to 3 months to see its full effect. Metformin is a preferred initial oral treatment for people with type 2 diabetes, and is usually taken on a long-term basis. It may be combined with other blood glucose-lowering treatments, if needed. Continue reading

When is the best time to take metformin?

Metformin should be taken after having a meal or eating food, especially when you are first starting treatment. This can help reduce any stomach side effects like nausea, vomiting, diarrhea or gas. These side effects generally go away within a few weeks after starting treatment. Continue reading

What is the safest diabetes medication?

Most experts consider metformin to be the safest medicine for type 2 diabetes because it has been used for many decades, is effective, affordable, and safe. Metformin is recommended as a first-line treatment for type 2 diabetes by the American Diabetes Association (ADA). Continue reading

Related medical questions

Related support groups