Several medications can cause weight fluctuations; most times it is not the drug but the side effects from the drug. Some drugs stimulate or dampen your appetite, and as a result, you eat more or less. Others may affect how your body absorbs and stores glucose, which can lead to fat deposits in the midsection of your body. Some cause calories to be burned faster or slower by changing your body’s metabolism. Others cause shortness of breath and fatigue, making it difficult for people to exercise. Other drugs can cause you to retain water, which adds weight but not necessarily fat.
How much weight is gained or lost varies from person to person and from drug to drug. Some people may gain a few pounds throughout the course of a year, other people can gain 10, 20, or more pounds in just a few months while others lose weight significantly. Because many of these medications are taken for chronic conditions, you may use them for several years with their use contributing to significant weight gain or loss throughout time.
What is Metformin?
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.
Metformin is also often prescribed off-label to treat polycystic ovary syndrome (PCOS), but it isn’t currently FDA-approved for this use. Metformin oral tablet comes in two forms: immediate-release and extended-release. The immediate-release tablet is available as a generic drug. The extended-release tablet is available as the brand-name drugs Fortamet and Glumetza.
Metformin can cause mild and serious side effects. Most side effects are mild and primarily affect your digestive system. Severe side effects such as lactic acidosis are less common but require prompt medical attention.
How Metformin works
Metformin belongs to a class of drugs called biguanides. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.
Metformin works by:
• reducing the amount of glucose (sugar) made by your liver
• decreasing the amount of glucose your body absorbs
• increasing the effect of insulin on your body
Insulin is a hormone that helps your body remove extra sugar from your blood. This lowers your blood sugar levels.
How should I take Metformin?
Metformin comes as a liquid, a tablet, and an extended-release (long-acting) tablet to take by mouth. The liquid is usually taken with meals one or two times a day. The regular tablet is usually taken with meals two or three times a day. The extended-release tablet is usually taken once daily with the night meal.
Metformin is usually started as 500 mg by mouth twice daily or 850 mg by mouth once daily. Depending on how well it works, the dose can be raised to a total of 2,550 mg by mouth per day split into a few doses throughout the day.
To help you remember to take metformin, take it around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take metformin exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Swallow metformin extended-release tablets whole; do not split, chew, or crush them.
Your doctor may start you on a low dose of metformin and gradually increase your dose not more often than once every 1–2 weeks. You will need to monitor your blood sugar carefully so your doctor will be able to tell how well metformin is working.
Metformin controls diabetes but does not cure it. Continue to take metformin even if you feel well. Do not stop taking metformin without talking to your doctor.
Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.
Does metformin cause weight loss?
Yes, but metformin is not an effective weight loss medication because the amount of weight you’re likely to lose while taking metformin is low. In one diabetes prevention study, 29% of people lost 5% or more of their body weight and just 8% lost around 10%. According to one long-term study, weight loss from metformin happened gradually over one to two years. And the average amount of weight loss in that time ranged from 4 to 7 pounds.
Although The FDA has not approved metformin for weight loss purposes, some doctors prescribe it for people who are overweight or obese and have type 2 diabetes or prediabetes. Studies have shown that the use of metformin decreases weight gain by reducing energy intake and is a useful adjunct to insulin therapy in patients with Type II diabetes.
Does metformin cause weight gain?
No, metformin does not cause weight gain like some of the medicines used to treat type 2 diabetes. Metformin triggers a modest reduction in weight, most likely due to side effects, like a decreased appetite and an upset stomach. If you have been gaining weight after starting metformin, ask your doctor if the new medication could be to blame.
Most medications that cause weight gain will have their effect early – within six months of starting. Importantly, it is not just a matter of putting on a few pounds. Extra weight, regardless of where it comes from, can cause or worsen health conditions.
Metformin side effects
Metformin can cause mild or serious side effects. The following list contains some of the key side effects that may occur while taking metformin. This list does not include all possible side effects.
More common side effects
The more common side effects that can occur with metformin include:
• stomach problems:
o diarrhea
o gas
o heartburn
o nausea
o stomach pain
If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.
Serious side effects
Call your doctor right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:
• Lactic acidosis. Symptoms can include:
o dizziness or lightheadedness
o slow or irregular heart rate
o stomach pains, nausea, or vomiting
o tiredness
o trouble breathing
o unusual muscle pain
o unusual sleepiness
o weakness
• Hypoglycemia (low blood sugar). Symptoms can include:
o confusion
o dizziness
o drowsiness
o fast heart rate
o headache
o hunger
o irritability
o shaking or feeling jittery
o sweating
o weakness
• Low vitamin B12 levels. Symptoms can include:
o loss of appetite
o low energy
o muscle weakness
o tingling or numbness in the hands or feet
Metformin may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.
If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program by phone (1-800-332-1088).
