Ozempic vs Metformin: Which drug triumphs for weight loss?

When deciding which medication might be right for your weight loss journey, there are several factors to consider. The most important is which will match your unique biology, medical history, lifestyle, and prescription medication needs. Before we dive in to see how Ozempic® (also known as semaglutide) stacks up against metformin, one of the most widely prescribed type 2 diabetes drugs in the United States, keep in mind that you should be working with an obesity medicine expert to tailor a treatment plan that will set you up for success. 

Let’s get into it. Found is an online evidence-based obesity treatment clinic, and we’ve gathered research and resources to help you have an informed visit with your provider about Ozempic vs metformin for weight loss.

Ozempic vs metformin: How do they work?

Ozempic and metformin are both approved by the U.S. Food and Drug Administration (FDA) to treat type 2 diabetes. Both drugs help lower blood glucose levels in people with high blood sugar and who may be insulin resistant. 

Health care professionals also prescribe metformin and Ozempic off-label to treat excess weight and obesity as part of a medication-assisted approach to weight loss. Found’s experts recommend using these drugs for weight care should be done alongside a lifestyle and behavior change program customized to the individual.

Though they both can be used for weight loss, these medications differ in several ways.

More on Ozempic

Ozempic is a GLP-1 receptor agonist. GLP-1, or glucagon-like peptide 1, is a hormone your body releases primarily in your small intestines and colon. It slows digestion, helps produce insulin when you eat, and lowers blood sugar. Some people don’t make enough GLP-1, or their brains are not sensitive to it. Ozempic is a synthetic version of GLP-1. Because it mimics the effects of the natural GLP-1 hormone in your body, it slows digestion. This slowing, in turn, helps regulate your appetite so you feel fuller longer while consuming fewer calories.

Before taking Ozempic for weight loss, you should know that this is an injectable drug. It comes in a prefilled pen you inject under the skin—usually weekly.

In addition to Ozempic, semaglutide is also the active ingredient in the brand name medication Rybelsus®, which comes in a pill version. In 2021, the FDA approved Wegovy—which is also semaglutide–for chronic weight management in adults who have obesity (defined as a body mass index of 30 or greater) or adults who have excess weight (defined as a body mass index of 27) and at least one weight-related condition like high cholesterol, high blood pressure, or type 2 diabetes. It’s the first medication in its class to receive FDA approval for weight management since 2014.  And some insurance companies will cover it to treat obesity. 

More on metformin

Metformin has been an FDA-approved medication to treat type 2 diabetes since 1994. Unlike Ozempic, metformin doesn’t mimic the GLP-1 hormone. It belongs to a different drug class called biguanides, medicines that inhibit the amount of glucose the liver produces, which lowers the amount of sugar your intestines absorb. 

Much like Ozempic, medical professionals prescribe metformin for weight loss even though it isn’t FDA approved for that use because of the evidence supporting its effectiveness. A study published in the journal Diabetes Care found that “metformin produces a highly significant reduction in body weight and waist circumference” and noted that participants who continued to take metformin sustained their weight loss for 10 years.

It’s also worth noting that metformin is usually the first of these two medications physicians prescribe to a patient. If a health care professional determines that metformin hasn’t worked for the patient, they might prescribe Ozempic. Trying a less expensive drug first is a common practice called step therapy. It can be helpful when navigating the complexity of insurance coverage for drugs like GLP-1s. 

In addition to weight loss, metformin has also been linked to other health benefits. Among them are possible cardiovascular health improvements and easing polycystic ovary syndrome (PCOS) symptoms. Metformin has also been shown to help with the effects of weight gain due to antipsychotics—a 2016 meta-analysis published in BMC Psychiatry showed that patients treated with metformin and atypical antipsychotics showed a significant weight loss compared to those patients who took a placebo.

Metformin is a pill taken in either immediate or extended-release form once or twice daily.

How much weight can you lose?

Both Ozempic and metformin can be effective when prescribed off-label for weight loss. When you consult with a Found-affiliated provider, talk with them about which is right for you based on your individual biological profile. The reason is simple—you are unique, and so is the medication (or combination of medications) that will help you lose weight. 

That said, a cohort study that analyzed the effectiveness of semaglutide (Ozempic) at doses used in clinical trials to treat obesity concluded that of the 175 patients with overweight or obesity, the total body weight loss percentages were 5.9% at three months and 10.9% at six months.

It’s worth noting that the manufacturer writes that Ozempic’s effectiveness varies from person to person and can take longer, depending on factors like age, weight, the amount of body fluid you have, your kidney and liver health, and other medications you take. 

When assessing metformin’s effectiveness, one study of metformin and weight loss in 2001 on 31 non-diabetic obese participants found that after 28 weeks, participants lost an average of about 16 pounds. Another study of 3,234 participants showed that 28.5% achieved roughly 5% weight loss within the first year of taking metformin. Metformin can also be used side-by-side with other diabetes medications to increase efficacy. 

Ozempic vs metformin: How much do they cost?

Ozempic’s list price is notoriously high—$935.77. The manufacturer does offer a coupon similar to savings cards for other medications. The terms on the Ozempic Savings Card state that only patients with private or commercial drug insurance policies that cover Ozempic can redeem the coupon and, if eligible, pay as little as $25 for up to a three-month supply. 

Insurance coverage for drugs like Ozempic has waned in recent months. When surveying the patient population at Found, we learned that insurance coverage for GLP-1s has dropped by 50% since December 2022. Nearly 70% of insurance plans showed no coverage of the drug class for anti-obesity or diabetes indications in June 2023. The media frenzy around this medication has led to overprescribing, supply issues, and unprecedented consumer demand.

In contrast, metformin is widely available and very affordable. Various online retailers offer discounted programs for this generic medication—some of which claim your total price might be lower than your copay. Some prices range in the single and double digits, depending on the retailer. 

Metformin vs Ozempic: Side effects

As with any prescription medication, there can be side effects. Here are some of the most common ones that participants in controlled trials have reported, according to the FDA:

Common side effects

Side effects of metformin

• Low blood sugar (hypoglycemia)
• Nausea
• Diarrhea

Side effects of Ozempic

• Nausea
• Diarrhea
• Vomiting
• Stomach pain
• Constipation
• Gastrointestinal issues
• Bloating

Metformin vs Ozempic: Warnings

We want you to be fully aware of what you’re taking. So here’s the run-down on warnings to consider as you explore metformin vs Ozempic.

Ozempic

Although rare, in animal studies, semaglutide caused thyroid c-cell tumors.Ozempic’s “black box” warns of the risk of these tumors. If you have trouble swallowing, develop hoarseness, or feel swelling or a lump in your neck, contact your health care provider immediately. 

The FDA also warns not to take Ozempic if you have or have a family history of multiple endocrine neoplasia syndrome type 2, medullary thyroid cancer, insulin-dependent diabetes, or diabetic ketoacidosis. So, if that’s you, Ozempic isn’t the right fit.

Metformin

The FDA also has a “black box warning” on metformin as it carries a serious safety risk of lactic acidosis. This rare but potentially fatal condition causes too much lactic acid in the blood. It can lead to low blood pressure, breathing issues, heart failure, and even death.

Additionally, metformin may stimulate ovulation in those with PCOS or who are premenopausal and may increase the risk of unintended pregnancy.  If you’re in a sexual relationship that can result in pregnancy, use at least one form of birth control unless you’re planning on getting pregnant.

Ozempic vs metformin: Are there drug interactions?

It’s important to work with a clinician who specializes in obesity medicine before picking the right medication for your weight loss goals based on your unique biology and medication needs, as serious drug interactions can occur. Here’s what we know.

Metformin

Some drugs can make metformin less effective or increase your risk of lactic acidosis or low blood sugar. 

Some things that can interact with metformin include:

• Insulin
• Carbonic anhydrase inhibitors
• Cephalexin
• Cimetidine
• Dolutegravir
• Glycopyrrolate
• Iodine contrast agents
• Lamotrigine
• Ranolazine
• Topiramate

Ozempic

Some drugs can also interact with Ozempic, including:

• Insulin
• Sulfonylureas (these can cause blood sugar levels to drop dangerously low when combined with Ozempic) 
• Some birth control pills
• Trulicity® (also known as dulaglutide—another type 2 diabetes medication)

Whether your health care professional prescribes metformin or Ozempic, you should not drink alcohol when taking these drugs because it can lower blood sugar. Combining alcohol with these medications may cause blood sugars to fall too fast, leading to fainting and dizziness.

Ozempic vs metformin: Which is best?

The truth is—it depends. There are so many factors that go into picking the right medication for weight loss. An obesity medicine expert can help you navigate which one is the best fit for you.

Ozempic can be difficult to get (even with a prescription), and not everyone sees results with it. However, it can be very effective for many. In contrast, metformin is easy to get and is cost-effective, allowing you to jumpstart your medication-assisted weight loss journey faster. Having a documented history of taking metformin can also help you unlock a GLP-1 prescription later in your treatment if you and your clinician find that metformin isn’t helping you.

Found-affiliated clinicians thoroughly assess each person’s  unique profile to create a tailored medication-assisted weight care plan because we know that one size doesn’t fit all. To start your journey with Found, take our quiz.