Conditions and symptoms
What Is Lactic Acidosis? A Rare Metformin Warning
Lactic acidosis · say it: LAK-tik as-ih-DOH-sisAlso written: lactic acidaemia, metformin-associated lactic acidosis, raised lactate
Short answer
Lactic acidosis is a build-up of lactic acid in the blood that makes it too acidic. It is rare but serious and needs urgent care.
What it means
Lactic acidosis means too much lactic acid (lactate) has built up in the blood, making it too acidic. It can happen with severe infection, shock, low oxygen, liver failure and, rarely, with some medicines. Symptoms can include feeling very unwell, fast breathing, muscle pain or weakness, belly pain, sleepiness and low blood pressure. It is a medical emergency needing urgent help.
The best-known warning is on metformin labels. Lactic acidosis with metformin is rare, but the risk is higher in people with poor kidney function, severe liver disease, heavy alcohol use, dehydration, serious infection, heart failure, or around the time of X-ray dye (contrast) scans and surgery. That is why kidney function is checked and why metformin is sometimes paused. Some HIV medicines also list it.
Lactic acidosis is different from the burning feeling in muscles during hard exercise, which is short-lived. It is also different from ketoacidosis, where the acid comes from ketones.
Where you may see it
- Boxed warning on metformin labels
- Some older HIV medicine labels
- Hospital blood gas and lactate results
📄 How it looks on a report
Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias.
🙅 What it does not mean
- It is rare; most people take metformin without this problem.
- Muscle burning during exercise is not lactic acidosis.
- It does not mean you should stop metformin on your own; ask your doctor about any concerns.
🎯 Check yourself
Which of these is the right meaning of “Lactic acidosis”?
🗒️ Questions to ask your doctor
💊 Medicines whose labels mention “Lactic acidosis”
Plain-English explanations of each medicine, from its official FDA label.
- Lamivudine
An antiviral medicine of the nucleoside analogue reverse transcriptase inhibitor type, used here for hepatitis B
- Metformin
a diabetes medicine of the biguanide type
- Tenofovir Disoproxil Fumarate
A nucleotide analog medicine. The label calls it an HIV-1 reverse transcriptase inhibitor and an HBV reverse transcriptase inhibitor. The FDA class is not listed.
🔗 Read more from trusted sources
- “Lactic acidosis” on MedlinePlus ↗
US National Library of Medicine
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