Metformin Side Effects: What You Need to Know Before Taking It

When you’re prescribed metformin, a first-line oral medication for type 2 diabetes that helps lower blood sugar by improving how your body uses insulin. Also known as Glucophage, it’s one of the most common diabetes drugs in India and around the world—cheap, effective, and often the first choice for doctors. But while it works well for millions, it’s not without its downsides. Many people start taking it expecting quick results, only to be caught off guard by stomach upset, fatigue, or worse.

The most common metformin side effects, include nausea, diarrhea, bloating, and loss of appetite—especially when you first start or increase the dose. These aren’t rare. Studies show up to 30% of users deal with them, and most ease up after a few weeks. Taking it with food helps a lot. But if the symptoms stick around or get worse, it’s not something you should just ignore. Then there’s the less common but serious risk: lactic acidosis, a dangerous buildup of lactic acid in the blood that can happen if your kidneys aren’t working right or you’re dehydrated. It’s rare—less than 1 in 10,000—but it’s life-threatening. That’s why doctors check your kidney function before and during treatment.

Some people take metformin for weight loss, even without diabetes. It doesn’t make you lose weight like Ozempic, but it can help reduce appetite and improve insulin sensitivity, which often leads to modest drops in body weight. That’s why it shows up in weight loss blogs and supplement forums. But using it without a prescription is risky. The side effects don’t disappear just because you’re not diabetic. And if you have liver or kidney problems, heart failure, or drink alcohol regularly, metformin can be dangerous.

What most people don’t tell you is that metformin can also lower vitamin B12 levels over time. That’s not a quick problem—it builds up slowly. Low B12 can cause numbness, fatigue, memory issues, and even nerve damage if left unchecked. If you’ve been on metformin for more than a year, ask your doctor for a simple blood test. It’s easy to fix with supplements, but only if you know it’s happening.

There’s no one-size-fits-all answer to whether metformin is right for you. It works wonders for some, and for others, the side effects make it unbearable. The key is knowing what to watch for, when to push back, and how to talk to your doctor about alternatives. Below, you’ll find real stories, science-backed facts, and clear advice from people who’ve been there—whether they’re managing diabetes, dealing with nausea, or wondering if they should keep taking it.