Pharmacist's 'problem' side effect warning to anyone on metformin for 'long time'

Pharmacist's 'problem' side effect warning to anyone on metformin for 'long time' Millions taking the common medication are being urged to watch out for certain side effects A pharmacist has issued a warning about a possible side effect that could cause 'problems' for anyone taking metformin - especially if they have been prescribed it for a long time. Speaking to the Daily Mirror, pharmacist Anil Sharma, who is a Committee Member and Regional Representative for the East of England at Community Pharmacy England, explained what patients should be aware of. According to the latest data, more than 150 million people worldwide take metformin daily, making it the most widely prescribed medication for type 2 diabetes. In the UK, more than three million people are said to be taking the medication. Metformin is a prescription medication primarily used as the first-line treatment to lower blood sugar levels in people with type 2 diabetes. It works by reducing the amount of sugar produced by the liver, decreasing sugar absorption in the intestines, and increasing the body's sensitivity to insulin. Doctors may also prescribe metformin to help manage insulin resistance and regulate menstrual cycles in people with Polycystic Ovary Syndrome (PCOS), as well as to delay or prevent the onset of type 2 diabetes in high-risk people with prediabetes, and to control blood sugar during gestational diabetes. For this reason, it is very common to be on metformin for a long time. Largely because it manages chronic, long-term conditions rather than curing them, meaning many people take it for years. How long can you take metformin and what should you watch out for? Clinical evidence shows that metformin is generally safe for extended use, and there is no maximum timeframe for how long you can stay on it, provided your kidneys remain healthy. Some people, however, may stop taking metformin if they achieve type 2 diabetes remission through significant lifestyle and weight changes, or if they were taking it temporarily to manage gestational diabetes during a pregnancy. Because the drug is cleared from the body by the kidneys, doctors typically check your kidney function to ensure it remains safe to continue the medication. However, Anil Sharma says there can be 'problematic' side effects caused by taking the common medication for a long time. For long-term users, which he describes as people who have been on it for at least 4-5 years, or longer, it can cause issues with absorbing a certain vitamin. He said taking metformin over several years can sometimes block the absorption of vitamin B12, leading to a deficiency, as it inhibits a specific transporter in the gut called THTR-2. According to Gov.uk, when taking metformin long term, it is vital to monitor your Vitamin B12 levels closely. It says that developing a vitamin B12 deficiency is considered a common side effect affecting up to one in 10 people. "The risk of low vitamin B12 levels increases with higher metformin dose, longer treatment duration, and in patients with risk factors for vitamin B12 deficiency," a statement reads. Why is a vitamin B12 deficiency a problem? Anil Sharma said: "This is a problem since it can cause nerve damage (numbness, burning, or tingling in your hands and feet), anaemia (tired, weak, and dizzy), memory loss, confusion and depression." Usually, your doctor will monitor your B12 levels every few years to prevent deficiency. A vitamin B12 deficiency is a serious health issue because the body relies entirely on this nutrient to produce healthy red blood cells, build DNA, and maintain the protective myelin sheaths surrounding your nerves. When B12 levels drop too low, it can lead to megaloblastic anaemia, which deprives organs of oxygen and causes chronic fatigue, weakness, and breathlessness. Over time, an unmanaged deficiency causes progressive, sometimes irreversible, nerve damage, resulting in persistent numbness, tingling in the hands and feet, muscle weakness, and loss of physical balance. A lack of B12 also disrupts crucial brain chemistry, potentially causing severe brain fog, memory loss, depression, or mood changes, alongside physical signs like a swollen, sore, red tongue and a pale or yellowish skin tone. If you're on metformin, talk to your doctor if you notice new or worsening signs such as feeling very tired, a sore, red tongue, pins and needles, or pale or yellow skin. These could indicate low vitamin B12 levels. You might need blood tests to figure out what's causing these symptoms, as they can also be linked to diabetes or other health problems. You can continue taking metformin while your vitamin B12 levels are being fixed. Just make sure to talk to your doctor before stopping your treatment.