Can you take metformin while pregnant?
Can you take metformin while pregnant? Sometimes. It may be used in pregnancy for diabetes or insulin resistance, depending on your situation.
Key facts
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If you are pregnant or trying to conceive, it is reasonable to ask, "can you take metformin while pregnant" before you keep taking it. Metformin is FDA-approved for type 2 diabetes, and some clinicians continue it during pregnancy when benefits outweigh risks. This page explains what labeling and guidelines say, what side effects to watch for, and when to call a clinician. If you want help applying this to your history, Vitals Vault includes PocketMD, a free tool for non-emergency questions.
- Sometimes, yes, if your clinician recommends metformin during pregnancy.
- Metformin is FDA-approved for type 2 diabetes, and some clinicians use it in pregnancy.
- Do not start, stop, or change metformin in pregnancy without medical guidance.
- Seek urgent care for possible lactic acidosis symptoms, including severe weakness or trouble breathing.
Can you take metformin while pregnant?
Why it may be used
Keeping blood sugar in a healthy range during pregnancy can lower risks for you and the pregnancy. For some people, a clinician may use metformin as part of a plan for type 2 diabetes or gestational diabetes, or to address insulin resistance.
Why it is individualized
Pregnancy changes insulin needs and glucose targets can shift quickly. Your clinician weighs your diagnosis, prior response, kidney function, and whether insulin or other approaches are needed.
What to do next
If you are already taking metformin and find out you are pregnant, contact the clinician who prescribes it and your OB. If you are considering metformin, ask what the goal is, what alternatives exist, and how you will be monitored.
Details that matter for safety in pregnancy
What metformin does
Metformin lowers blood sugar mainly by decreasing glucose production in the liver and improving insulin sensitivity. In pregnancy, the goal is usually glucose control, not weight loss.
Common side effects
Common side effects are gastrointestinal, such as diarrhea, nausea, and stomach upset. Some people tolerate extended-release formulations better, but you should follow your prescriber’s plan.
Low blood sugar
Metformin alone is less likely to cause low blood sugar than some other diabetes medicines, but low blood sugar can still occur, especially if combined with insulin or other glucose-lowering drugs. Ask your clinician what symptoms to watch for and what to do if they happen.
Lactic acidosis
Metformin has a boxed warning for lactic acidosis, a rare but life-threatening buildup of lactic acid. Risk is higher with significant kidney problems and certain acute illnesses. Get emergency care for severe weakness, unusual muscle pain, trouble breathing, worsening sleepiness, or severe stomach symptoms.
Kidney function matters
Metformin is cleared by the kidneys, so reduced kidney function can increase metformin levels and raise lactic acidosis risk. Your clinician may check kidney function and review any conditions that could cause dehydration or reduced blood flow to the kidneys.
Vitamin B12 can run low
Long-term metformin use can be associated with vitamin B12 deficiency. If you have fatigue, numbness, tingling, or anemia concerns, ask whether B12 testing is appropriate, especially if you have been on metformin for a long time.
When to talk to a clinician urgently vs soon
| Situation | What it could mean | What to do |
|---|---|---|
| Severe weakness, trouble breathing, unusual muscle pain, severe sleepiness, or severe stomach symptoms | Possible lactic acidosis (rare but serious) | Seek emergency care now and tell them you take metformin |
| Repeated vomiting or diarrhea, cannot keep fluids down | Dehydration can increase metformin risk and destabilize glucose | Call your prenatal clinician the same day for guidance |
| Shakiness, sweating, confusion, or faintness (especially if also on insulin) | Possible low blood sugar | Follow your clinician’s hypoglycemia plan and contact them promptly |
| New or worsening fatigue, numbness, or tingling | Possible vitamin B12 deficiency or anemia | Discuss at your next visit or sooner if symptoms are significant |
Bring these questions
Ask why metformin is being used in your pregnancy, what the plan is if glucose goals are not met, and what monitoring is recommended. Also ask whether any other medicines or supplements you take could affect blood sugar or kidney function.
Tell your clinician about
Share any history of kidney disease, liver disease, heavy alcohol use, or prior lactic acidosis. Also report any acute illness with fever, vomiting, diarrhea, or reduced eating and drinking, because these can change risk.
If you are trying to conceive
If you are taking metformin for PCOS or insulin resistance, ask your clinician what to do if you become pregnant and whether the plan changes by trimester. The right approach depends on your diagnosis and pregnancy risk factors.
Practical tips to discuss with your care team
Confirm the goal
Ask whether the goal is glucose control, insulin resistance, or both.
Review all meds
Bring a list of prescriptions, supplements, and over-the-counter products.
Know your sick-day plan
Ask what to do if you cannot eat or drink normally due to illness.
Ask about monitoring
Clarify how often glucose and kidney function should be checked.
Report GI symptoms early
Persistent diarrhea or vomiting can cause dehydration and needs attention.
Frequently Asked Questions
Can you take metformin while pregnant if you have type 2 diabetes?
Sometimes, yes. Metformin is FDA-approved for type 2 diabetes, and some clinicians use it during pregnancy when it helps meet glucose goals. Your OB or endocrinologist should confirm whether it fits your situation and monitoring plan.
Is metformin safe in the first trimester?
Some people continue metformin early in pregnancy, but safety decisions are individualized. Your clinician weighs potential benefits for glucose control against uncertainties and your specific risk factors. Do not change therapy without medical guidance.
What side effects should I watch for if I take metformin while pregnant?
Common side effects include diarrhea, nausea, and stomach upset. Rarely, metformin can cause lactic acidosis, which is an emergency if you have severe weakness, trouble breathing, unusual muscle pain, or severe stomach symptoms. Contact your clinician if you cannot keep fluids down.
Can metformin cause low blood sugar during pregnancy?
Metformin alone is less likely to cause low blood sugar than some diabetes medicines, but low blood sugar can occur, especially if combined with insulin or other glucose-lowering drugs. Ask your clinician what symptoms to watch for and what to do if they happen.
Should I stop metformin as soon as I find out I am pregnant?
Do not stop metformin on your own. Contact the clinician who prescribes it and your prenatal clinician promptly so they can review why you are taking it and whether any changes are needed. Sudden changes can destabilize blood sugar.