Side effects of metformin
Metformin can cause mild side effects that primarily affect your digestive system, such as nausea or vomiting. Severe side effects like lactic acidosis are rare, but they require prompt medical attention.
Metformin is a prescription drug used to treat type 2 diabetes. It belongs to a class of medications called biguanides. People with type 2 diabetes have blood sugar (glucose) levels that rise higher than normal. Metformin doesn’t cure diabetes. Instead, it helps lower your blood sugar levels to a safe range. Here’s what you need to know about metformin side effects and when you should call your doctor.
More common side effects of metformin
Metformin causes some common side effects. These can occur when you first start taking metformin but usually go away over time. Tell your doctor if any of these symptoms are severe or cause a problem for you.
The most common side effects of metformin include:
· heartburn
· stomach pain
· nausea or vomiting
· bloating
· gas
· diarrhoea
· constipation
· weight loss
· headache
· unpleasant metallic taste in mouth
Nausea, vomiting, and diarrhoea are some of the most common side effects people have when they first start taking metformin. These problems usually go away over time. You can reduce these effects by taking metformin with a meal. Also, to help lessen your risk of severe diarrhoea, your doctor will likely start you on a low dosage of metformin and then increase it slowly.
Metformin is sometimes used to improve insulin sensitivity and help regulate ovarian function in people with PCOS. The side effects for this use are the same as for other uses.
Serious side effects of metformin
Lactic acidosis
Although very rare, metformin’s most serious side effect is lactic acidosis. Lactic acidosis is a rare but serious problem that can occur due to a build-up of metformin in your body. This build-up causes a pH imbalance in your body. It’s a medical emergency that must be treated right away in the hospital.
The death rate of metformin-associated lactic acidosis is between 30-50%, but it’s only reported 10 times per every 100,000 patient-years. For example, if 200,000 people took metformin for one year each, there would be about 20 cases expected.
Call your doctor right away if you have any of the following symptoms of lactic acidosis. If you have trouble breathing, call 999 right away or go to the nearest emergency room.
· extreme tiredness
· weakness
· decreased appetite
· nausea
· vomiting
· trouble breathing
· dizziness
· light-headedness
· a fast or slow heart rate
· feeling cold
· muscle pain
· flushing or sudden reddening and warmth in your skin
· stomach pain with any of these other symptoms
Anaemia
Metformin can decrease the levels of vitamin B12 in your body. In rare cases, this can cause anaemia or low levels of red blood cells. If you don’t get much vitamin B12 or calcium through your diet, you may be at higher risk of very low vitamin B12 levels. Your vitamin B12 levels can improve if you stop taking metformin or take vitamin B12 supplements. Make sure to talk with your doctor before you stop taking metformin.
The more common symptoms of anaemia include:
· tiredness
· dizziness
· light-headedness
If you think you may have anaemia, make an appointment with your doctor to have your red blood cell levels checked.
Hypoglycaemia
Metformin doesn’t usually cause hypoglycaemia or low blood sugar. However, in rare cases, you may develop hypoglycaemia if you combine metformin with:
· a poor diet
· strenuous exercise
· excessive alcohol intake
· other diabetes medications
Call your doctor if you have any symptoms of hypoglycaemia, which can include:
· weakness
· tiredness
· nausea
· vomiting
· stomach pain
· dizziness
· light-headedness
· abnormally fast or slow heartbeat
Side effects during pregnancy
Metformin is usually safe to take by itself or with insulin while pregnant or breastfeeding. Metformin crosses the placenta but has not been linked to increased rates of foetal development issues or complications.
A 2018 study found no significant difference between the rate of serious adverse events in pregnant women who either took a placebo or metformin. Mild side effects such as nausea, vomiting, and diarrhoea were reported more often in women who took metformin. A 2016 review of studies found evidence that metformin may reduce the rate of miscarriage in women with PCOS.
Managing the side effects of Metformin
Most of the common side effects of metformin involve your digestive system. You can minimise your chances of developing side effects by:
· Starting with a low dose. It’s best to start at a low dose and work up over time to reduce the chances of developing side effects.
· Taking metformin with a meal. Taking metformin with a meal can help reduce your chances of developing an upset stomach or gastric discomfort.
· Taking extended-release metformin. You can talk with a doctor to see if extended-release metformin might be right for you. This type of metformin releases slowly over time and typically has milder side effects. Be sure to discuss the FDA recall of certain brands of metformin extended release, to ensure you’re getting a safe version.
· Taking pills whole. You shouldn’t crush up pills. Doing so can speed up the rate that they’re absorbed.
If you develop uncomfortable side effects, it’s a good idea to contact your doctor. They may recommend changing the dosage of the type of metformin you’re taking. For example, from a fast acting to a slow acting form of metformin. You may find that you need to change your dosage, particularly during periods of stress, or your body may simply not like the medication.
It’s also a good idea to avoid drinking heavily when taking metformin because it can increase your chances of developing lactic acidosis.
Risk factors for experiencing side effects
Several factors raise your risk of lactic acidosis while taking metformin. If any of these factors affect you, be sure to discuss them with your doctor before taking this drug.
Kidney problems
Your kidneys remove metformin from your body. If your kidneys don’t work well, you’ll have higher levels of metformin in your system. This raises your risk of lactic acidosis. If you have mild or moderate kidney problems, your doctor may start you at a lower dosage of metformin.
If you have severe kidney problems or are ages 80 or older, metformin may not be right for you. Your doctor will likely test your kidney function before you start taking metformin and then again each year.
Heart problems
If you have acute heart failure or have recently had a heart attack, you should not take metformin. Your heart may not send enough blood to your kidneys. This would prevent your kidneys from removing metformin from your body as well as they normally would, raising your risk of lactic acidosis.
Liver problems
You should not take metformin if you have severe liver problems. Your liver clears lactic acid from your body. Severe liver problems could lead to a build-up of lactic acid. Lactic acid build-up raises your risk of lactic acidosis. Metformin also raises your risk, so taking it if you have liver problems is dangerous.
Alcohol use
Drinking alcohol while taking metformin raises your risk of hypoglycaemia. It also raises your risk of lactic acidosis because it increases lactic acid levels in your body. You should not drink large amounts of alcohol while taking metformin. This includes long-term alcohol use and binge drinking. If you drink alcohol, talk with your doctor about how much alcohol is safe for you while you take metformin.
For more information, read about the dangers of drinking with metformin use and how alcohol affects diabetes.
Takeaway
If your GP has prescribed metformin and you’re concerned about its side effects, talk with your GP. You may want to review this article with them. Be sure to ask any questions you have, such as:
· What side effects should I watch out for?
· Am I at high risk of lactic acidosis?
· Is there another medication I could take that might cause fewer side effects?
Your GP can answer your questions and work with you to manage any side-effects you may have.
Extracts taken from Daniel Yetman from https://www.healthline.com