Across 175 first-hand reports, people mentioned a side effect 38 times (about 22 per 100 reports). The most common: stomach issues, diarrhea, b12 depletion. User reports show what people notice — they can't tell you whether Metformin is safe for you.
“Berberine has done zero for my pre diabetic glucose levels or weight. Metformin has and I changed nothing else.”
“2 days with Metformin and that’s gone. I feel like I did when i was in my 30’s.”
“Recently, he stopped because it was found to interfere with some other important function (muscle building?, I can't remember), so he stopped taking it. He said the benefits did not outweigh the costs.”
“Personally, I used metformin for 2 years, though I stopped for a multitude of reasons.”
“Terrible side effects for me stomach wise and didnt particularly impact my blood sugar either...A1c went from 5.9 to 5.6 on metformin.”
“I had brutal diarreah and stomach aches for weeks and then I stopped it. Can't handle it.”
Conclusion: In diabetic patients at low cardiovascular risk, no treatment differs from placebo for vascular outcomes. In patients at increased cardiovascular risk receiving metformin-based background therapy, specific GLP-1 RAs and SGLT-2 inhibitors have a favorable effect on certain cardiovascular outcomes.
Conclusion: The evidence supports metformin as first-line therapy for type 2 diabetes, given its relative safety and beneficial effects on hemoglobin A1c, weight, and cardiovascular mortality (compared with sulfonylureas). On the basis of less evidence, results for add-on therapies to metformin were similar to those for monotherapies.
Conclusion: Metformin may be associated with a decreased risk of many cancer types, but high heterogeneity and risk of publication bias limit confidence in these results. Additional studies in populations without diabetes are needed to better understand the utility of metformin in cancer prevention.