{"chart":{"slug":"metformin-side-effects-reported","title":"Which side effects are reported most for metformin?","takeaway":"Nausea (30,587 reports) and diarrhea (28,674) are the reactions named most often in reports to the FDA, as of September 2026, that list a medicine containing metformin, including combination pills. Nausea and diarrhea are known stomach side effects of metformin; high blood sugar may describe the diabetes being treated, and lactic acidosis is a rare but serious known risk. A report is not proof the medicine caused the problem: anyone can send one, it lists every medicine the person was taking, and the same case can be reported twice. Reports that the medicine didn't work or was used differently than labeled are left out. Don't stop a medicine without talking to a doctor.","topic":"Food and drug safety","chart_type":"bar","ranking":false,"x_label":"Reported reaction","y_label":"Reports to the FDA naming metformin","unit":null,"points_count":15,"source":{"name":"U.S. Food and Drug Administration, Adverse Event Reporting System (FAERS) via openFDA","url":"https://open.fda.gov/apis/drug/event/"},"license":{"name":"Public domain (U.S. government work); source U.S. Food and Drug Administration, openFDA","url":"https://open.fda.gov/license/"},"data_as_of":"2026-09-30","updated_at":"2026-11-03T17:24:55.390Z","url":"https://chart.ly/charts/metformin-side-effects-reported","api_url":"https://chart.ly/api/v1/charts/metformin-side-effects-reported","csv_url":"https://chart.ly/charts/metformin-side-effects-reported/data.csv","image_url":"https://chart.ly/charts/metformin-side-effects-reported/image.png","embed_url":"https://chart.ly/charts/metformin-side-effects-reported/embed","credit":"U.S. Food and Drug Administration, Adverse Event Reporting System (FAERS) via openFDA, via Chartly (https://chart.ly/charts/metformin-side-effects-reported)","credit_html":"U.S. Food and Drug Administration, Adverse Event Reporting System (FAERS) via openFDA, via \u003ca href=\"https://chart.ly/charts/metformin-side-effects-reported\"\u003eChartly\u003c/a\u003e","average_label":null,"zero_axis":true,"data":[{"label":"Nausea","value":30587},{"label":"Diarrhea","value":28674},{"label":"High blood sugar (blood glucose increased)","value":27705},{"label":"Fatigue","value":21809},{"label":"Vomiting","value":20001},{"label":"Lactic acidosis (acid buildup in the blood)","value":19902},{"label":"Acute kidney injury","value":18756},{"label":"Weight loss","value":17655},{"label":"Shortness of breath","value":16956},{"label":"Dizziness","value":16099},{"label":"Headache","value":15374},{"label":"Pain","value":14514},{"label":"Weakness","value":13616},{"label":"Feeling unwell","value":12996},{"label":"Loss of appetite","value":12148}],"annotations":[]},"docs":"https://chart.ly/developers","terms":"Free to use with credit: wherever you show or quote a chart's data, name Chartly with a link to that chart's url (each chart's credit line does both) and credit its source as its license asks.","credit":"U.S. Food and Drug Administration, Adverse Event Reporting System (FAERS) via openFDA, via Chartly (https://chart.ly/charts/metformin-side-effects-reported)"}