Accidentally Took An Extra Dose Of Metformin

In our latest question and answer, the pharmacist discusses concerns an individual has after accidentally taking two tablets of metformin.

5 min read Updated Jun 2026 Read by 22,498 people
Accidentally Took An Extra Dose Of Metformin
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Larkin asked

I'm a little worried because this morning, I took my metformin 500mg as usual and I must have just not been thinking and I took another one. So, I took two by accident. Am I going to be okay? Thanks for your help

Mar 25, 2023
The quick answer
  • Metformin is unlikely to cause dangerous low blood sugar even if you take an extra dose because it works differently than other diabetes medications.
  • You may experience mild side effects like stomach cramping, nausea, or diarrhea, but these are usually temporary and should go away within a few hours.
  • An extra metformin tablet still keeps you within dosage ranges that are commonly used by people taking this medication daily.
A quick summary of Dr. Brian Staiger, PharmD's full answer below, condensed by AI from that answer only (not from any outside source). The pharmacist's answer is the source of record.
Medications in this answer — tap to explore

Answer

I completely understand why you may be worried after accidentally taking an extra dose of metformin. Medication errors can happen to anyone, and it's natural to feel concerned about the potential consequences.

While accidentally taking an additional metformin dose may put you at a higher risk of certain side effects, such as stomach cramping and diarrhea, it is important to note that while metformin is one of the safest and most commonly used medications for people with diabetes.

In general, the concern with taking too much of any diabetes medication is the risk of hypoglycemia (low blood sugar) occurring. Fortunately, in regard to metformin, is very unlikely to cause hypoglycemia, even if you took more than you were supposed to.

Additionally, accidentally taking two tablets of metformin instead of one would still likely put you in a dosage range that is commonly utilized for patients with diabetes (some individuals take up to 2,550mg per day of metformin).

Overall, you may experience some mild side effects, like stomach cramping, nausea, and diarrhea, but the risk of serious side effects occurring from one additional metformin tablet is quite low.

Diabetes Medications & Hypoglycemia

Hypoglycemia is a potential side effect of many different diabetes drugs and it's generally the side effect we are concerned about if you take too much of certain ones.

Hypoglycemia occurs when your blood sugar level drops below normal, which can cause a range of symptoms. The severity of symptoms can vary depending on how low your blood sugar level drops and how quickly it drops.

Early symptoms of hypoglycemia include:

  • Sweating
  • Shakiness or tremors
  • Feeling anxious or irritable
  • Fast heartbeat
  • Hunger
  • Blurry vision
  • Dizziness
  • Fatigue

If hypoglycemia continues and becomes more severe, symptoms can include:

  • Confusion or disorientation
  • Difficulty speaking or slurred speech
  • Seizures

The Risk Of Hypoglycemia With Metformin Is Low

Metformin is one of the safest and most commonly used medications for people with diabetes, and it's generally considered the least likely among diabetes medications to cause hypoglycemia (low blood sugar).

This is because metformin works by reducing the amount of glucose released by your liver, rather than increasing the amount of insulin in your body. Therefore, taking an extra dose of metformin is very unlikely to cause hypoglycemia.

Metformin does have additional actions as well (such as increasing glucose uptake into the muscles), but, again, this doesn't lend itself to causing blood sugar to drop too low.

Other medications used to treat diabetes, such as insulin and sulfonylureas, have a much higher risk of causing hypoglycemia.

Insulin is a hormone that regulates the amount of glucose in the blood, and taking too much insulin or not eating enough after taking insulin can cause hypoglycemia.

Sulfonylureas, on the other hand, work by stimulating the pancreas to release more insulin, which can also cause hypoglycemia if too much insulin is released.

Potential Side Effect Of Taking Too Much Metformin

As mentioned, the risk of hypoglycemia is very low from accidentally taking an extra dose of metformin.

The prescribing information for metformin even makes note that in cases of extreme overdose (50 grams ingested), hypoglycemia only occurred in 10% of individuals.

Now, you didn't mention what strength of metformin you are taking, but the maximum milligram amount per one metformin tablet is 1,000mg. Even if you took two tablets, that puts you at 2,000mg, which is under the maximum daily dose recommended by the FDA (Food and Drug Administration), which is 2,550mg per day for immediate-release formulations.

Regardless, if you took a dose of metformin higher than what you are used to, you certainly may have some mild side effects, such could include:

  • Nausea
  • Stomach cramping
  • Metallic taste in the mouth
  • Appetite loss
  • Soft bowel movements or diarrhea

Metformin is also associated with some more major side effects, like lactic acidosis and vitamin B12 deficiency, but it's very unlikely either of those with simply taking one additional tablet.

Additional Thoughts From The Pharmacist

It's important to emphasize that while taking an extra dose of metformin is unlikely to cause hypoglycemia, it can cause some mild side effects such as gastrointestinal symptoms like nausea, vomiting, diarrhea, and abdominal discomfort.

These symptoms are usually temporary and should subside within a few hours.

If you experience any of these symptoms, try to stay hydrated. Consuming small amounts of non-fatty foods, like simple carbohydrates, can help alleviate nausea and cramping that may happen.

So, overall, taking two doses of metformin isn't something to be overly concerned about. The risk of a serious problem from an extra dose of metformin is rare, especially if you have been taking the medication regularly as prescribed. However, if you experience any symptoms that are concerning or severe, such as difficulty breathing, dizziness, or confusion, please seek medical attention immediately.

As always, if you're worried about any potential side effects or have any concerns about your medication, don't hesitate to reach out to your healthcare provider. They can provide you with personalized advice and guidance based on your individual health history and medication regimen.

You can always contact Poison Control as well if you are concerned about taking too much of any medication. They can be reached at 1-800-222-1222, or visit their website at Poison.org.

Final Words

Thanks so much for reaching out and please do so again in the future!

References & sources
  1. Glucophage Prescribing Information — AccessFDA
  2. Metformin Monograph — PubChem
Glossary — Terms in This Answer
Metformin
A commonly prescribed medication used to help control blood sugar levels in people with diabetes.
Hypoglycemia
A condition where blood sugar levels drop below normal, which can cause symptoms like shaking, sweating, and confusion.
Glucose
A type of sugar that is the body's main source of energy and is controlled by the pancreas and liver.
Insulin
A hormone produced by the pancreas that helps regulate how much glucose stays in the blood.
Sulfonylureas
A class of diabetes medications that work by stimulating the pancreas to release more insulin.
Lactic acidosis
A serious condition where lactic acid builds up in the body faster than it can be removed, which can occur as a rare side effect of metformin.
Gastrointestinal
Relating to the stomach and digestive system.
Immediate-release formulations
Medications designed to dissolve and be absorbed quickly into the bloodstream rather than slowly over time.
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Dr. Brian Staiger, PharmD
About the pharmacist

Dr. Brian Staiger, PharmD

Clinical Pharmacy

Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified

Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...

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