Can you take metformin without food?

If you take metformin without food you may end up with an upset stomach, especially if you are just starting treatment. Nausea and vomiting are some of the most common side effects with metformin and can occur in over a quarter of patients.

Five of the top 7 side effects with metformin are stomach-related, and occur in the following percentages of patients: ​​

• Diarrhea - 53%
• Nausea / vomiting (throwing up) - 26%
• Flatulence / gas - 12%
• Indigestion - 7%
• Abdominal (stomach area) discomfort or pain - 6%

Loss of appetite, metallic taste in the mouth or a taste change, abnormal stools and weight loss have also been reported as gastrointestinal side effects with metformin.

In studies, 6% of patients taking metformin stopped treatment due to diarrhea. But in general, these side effects tend to go away within a few weeks after starting treatment.

Metformin is usually taken once or twice per day, but your dose may be different. If you take it once a day, it’s usually recommended to take it after an evening meal. If you take it twice per day, take it after your morning and evening meals. Take it at about the same time each day.

Why does metformin cause an upset stomach?

Stomach side effects with metformin can be related to quickly increasing the dose and use of high doses.

• Your doctor will probably slowly increase your dose over a period of several weeks to help minimize the stomach side effects due to metformin.
• If you have stomach side effects with this medicine, contact your doctor to see if your dose can be adjusted until you can better tolerate the medicine.

It's not really known why metformin leads to stomach problem but it may be related to its mechanism of increased gut mobility, serotonin-like effects, or effects due to increases in glucagon-like peptide 1 (GLP-1).

Once you get over the initial stomach side effects in a few weeks, metformin is usually well-tolerated by most people. If these side effects are severe, do not go away, or are worrisome to you, you should contact your healthcare provider right away.

Related: Metformin Warnings and Side Effects in Greater Detail

Metformin comes as an oral immediate-release and extended-release tablet and as an oral solution. Brand names for metformin include Glumetza, but most people use the much more affordable generic option. If you take the extended-release form, swallow it whole; do not crush, cut, split or chew the tablets.

This is not all the information you need to know about metformin for safe and effective use and does not take the place of your health care provider’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.

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