Warning Rarely, metformin may cause an acid health problem in the blood (lactic acidosis). The risk of lactic acidosis is higher in people with kidney problems and in people who take certain other drugs like topiramate. What is Riomet®?1 Riomet® (Metformin HCl Oral Solution) is an oral diabetes medicine that, along with diet and exercise, helps improve blood sugar con. Read this leaflet carefully before taking your medicine. This leaflet answers some common questions about metformin. It does not contain all the available information. It does not take the place of talking to your doctor or pharmacist or diabetes educator. The information in this leaflet was last APO-Metformin Tablets - Consumer Medicines Information leaflets of prescription and over-the-counter medicines Metformin makes my bbs sore and swollen and gives me a slight headache, but only in the afternoon after i take it. I only take 500 mg compared to some who take 1000mg. Consumer Medicine Information (CMI) about APO-Metformin (metformin hydrochloride) intended for persons living in Australia. Warning Rarely, metformin may cause an acid health problem in the blood (lactic acidosis). The risk of lactic acidosis is higher in people with kidney problems and in people who take certain other drugs like topiramate. JANUMET tablets contain 2 prescription medicines: sitagliptin (JANUVIA ®) and metformin. Once-daily prescription JANUMET XR tablets contain sitagliptin (the medicine in JANUVIA ®) and extended-release metformin. Hi I was put on metformin two days ago and I am not sure if what I am feeling are side effects or not. Starting late yesterday afternoon I got extremely tired and my back started to get sore, by night time my lower back was painful and my muscles were crampy and sore. What is Metformin? Metformin is one of the most commonly used oral anti-diabetic agents available for people with type 2 diabetes. It belongs to the biguanide drug class, which function to regulate blood sugar levels by increasing insulin sensitivity of the fat and muscle cells, reducing sugar production by the liver, and by reducing absorption.