WHY NOT TO TAKE METFORMIN
Medically reviewed by Alisha D. Sellers, BS Pharmacy, PharmD — Written by Daniel Yetman — Updated on November 29, 2021
RECALL OF METFORMIN EXTENDED RELEASE
In May 2020, the Food and Drug Administration (FDA)Trusted Source recommended that some makers of metformin extended release remove some of their tablets from the U.S. market. This is because an unacceptable level of a probable carcinogen (cancer-causing agent) was found in some extended-release metformin tablets. If you currently take this drug, call your healthcare provider. They will advise whether you should continue to take your medication or if you need a new prescription.
Lactic acidosis
Although very rare, metformin’s most serious side effect is lactic acidosis. In fact, metformin has a “boxed” — also referred to as a “black box” — warning about this risk. A boxed warning is the most severe warning that the Food and Drug Administration (FDA) issues.
Lactic acidosis is a rare but serious problem that can occur due to a buildup of metformin in your body. This buildup causes a pH imbalance in your body. It’s a medical emergency that must be treated right away in the hospital.
The death rate of metformin-associated lactic acidosis is between 30 and 50 percent, but it’s only reported 10 times per every 100,000 patient-years. For example, if 200,000 people took metformin for one year each, there would be about 20 cases expected.
Anemia
Metformin can decrease the levels of vitamin B12 in your body.
