Read on to learn more about metformin’s side effects, how it’s taken, and more. Note: Metformin also comes in an oral solution. But only the oral tablet form is described in this article. Common side effects of metformin hydrochloride tablets include diarrhea, nausea, vomiting, wind (flatulence), indigestion, and headache. These side effects occurred in 5% or more of patients in the US clinical trial of using metformin for type 2 diabetic patients. Overview: Metformin is medicine you take to help keep your blood sugar from getting too high. Common side effects may include stomach problems, such as diarrhea, nausea, vomiting, stomach pain. Metformin should be taken with meals to help reduce stomach or bowel side effects that may occur during the first few weeks of treatment. Swallow the tablet or extended-release tablet whole with a full glass of water. Metformin commonly causes side effects like nausea, diarrhea and bloating. More serious side effects involve low blood pressure and lactic acidosis. Metformin can cause side effects in some people. Learn about its mild and serious side effects, as well as factors that can increase your risk. NHS medicines information on side effects of metformin and what you can do to cope. Learn about the side effects of metformin, from common to rare, for consumers and healthcare professionals. Common metformin side effects include diarrhea, nausea, and vomiting. It can also cause fatigue, weight loss, and low vitamin B12 levels. While uncommon, metformin can also cause blood glucose (sugar) to drop too low and lactic acidosis. In severe cases, these side effects are medical emergencies. Many of the warning signs are similar to some metformin side effects, such as stomach pain, dizziness, and weakness. Others are numbness or a cold feeling in your limbs, or changes in your.