Wegovy vs. metformin: Differences, similarities & side effects

In this article:

• Wegovy vs. metformin: Key differences
• Wegovy vs. metformin: Conditions treated
• Is metformin better than Wegovy?
• Wegovy vs. metformin: Insurance coverage and cost comparison
• Wegovy vs. metformin side effects
• Wegovy and metformin drug interactions
• Wegovy and metformin drug warnings

In this article

• Wegovy vs. metformin: Key differences
• Wegovy vs. metformin: Conditions treated
• Is metformin better than Wegovy?
• Wegovy vs. metformin: Insurance coverage and cost comparison
• Wegovy vs. metformin side effects
• Wegovy and metformin drug interactions
• Wegovy and metformin drug warnings

For those managing diabetes or seeking weight loss options, Wegovy or metformin may be potential options. Both prescription medications have been shown to benefit blood sugar levels and body weight. Although they have similar benefits, they contain different active ingredients and work differently. They also have differences in their approved uses, costs, and side effects.

Wegovy vs. metformin: Key differences

Wegovy is a brand-name drug containing the active ingredient semaglutide. On the other hand, metformin is a generic drug that is known by the brand names Glucophage, Fortamet, and Riomet. Wegovy is a relatively new drug manufactured by Novo Nordisk and approved by the Food and Drug Administration (FDA) in 2021. Metformin has been around longer and was initially approved in 1995. 

Mechanism of action

Wegovy is classified as a glucagon-like peptide-1 (GLP-1) receptor agonist. It increases insulin release to help lower blood sugar levels and slows digestion to manage appetite. 

Metformin belongs to the biguanides drug class. It decreases glucose production in the liver and improves insulin sensitivity, supporting better control of blood sugar levels.

Dosage forms

Wegovy is a weekly injection administered subcutaneously (under the skin). The starting dose is 0.25 mg once weekly for four weeks. It then gradually increases to a target dosage of 2.4 or 1.7 mg once weekly. Wegovy is approved for adults and children 12 years and older.

Metformin is usually taken orally in pill form. Patients often take it twice daily, although extended-release versions are available that can be taken once daily. The typical dosage for regular immediate-release tablets is 500 milligrams (mg) twice daily or 850 mg once daily with meals. It is approved for adults and children 10 years and older.  

Compare Wegovy vs. metformin key differences
	Wegovy	Metformin
Drug class	GLP-1 receptor agonist	Biguanide
Brand/generic status	Brand-name only	Generic; brand-name versions available
What is the generic or brand name?	Generic name: Semaglutide	Generic name: Metformin Brand name: Glucophage, Riomet, Fortamet
What form(s) does the drug come in?	Subcutaneous injection	Oral tablet, Extended-release tablet, or Liquid oral suspension
What is the standard dosage?	0.25 mg injected under the skin once weekly for 4 weeks. Then, the dosage is gradually increased to 1.7 or 2.4 mg once weekly.	Immediate-release: 500 mg twice daily or 850 mg once daily with meals Extended-release: 500 to 2,000 mg once daily with an evening meal Dosage may be increased as needed and tolerated.
How long is the typical treatment?	Long-term	Long-term
Who typically uses the medication?	Adults and children 12 years and older	Adults and children 10 years and older

Wegovy vs. metformin: Conditions treated

Wegovy is FDA-approved for weight management in adults and children with obesity. It is also approved for adults who are overweight with at least one weight-related health condition, such as high blood pressure, diabetes, or high cholesterol. In addition to causing weight loss, Wegovy can help reduce the risk of heart disease-related events, such as heart attacks and strokes, in people with obesity or who are overweight. 

The active ingredient in Wegovy is available under a different brand name, Ozempic, which is approved to treat Type 2 diabetes. While Wegovy can help manage blood sugar levels in people with Type 2 diabetes, it is considered an off-label use of the medication. 

Metformin is approved to manage blood sugar levels in adults and children with Type 2 diabetes. Metformin is sometimes used off-label for managing symptoms of polycystic ovary syndrome (PCOS), such as insulin resistance and irregular menstrual cycles. Wegovy has also shown benefits for weight loss in women with PCOS. 

Wegovy and metformin are meant to be used alongside a healthy diet and exercise plan for maximum effectiveness. 

Compare Wegovy vs. metformin conditions treated
Condition	Wegovy	Metformin
Type 2 diabetes	Off-label	Yes
Weight management for patients with a body mass index (BMI) of 30 kg/m2 or greater	Yes	Off-label
Weight management for patients with a body mass index (BMI) of 27 kg/m2 or greater with at least one weight-related health condition	Yes	Off-label
Reduce the risk of heart attacks, strokes, and heart disease-related death in people who have obesity or are overweight	Yes	No
Polycystic ovary syndrome	Off-label	Off-label

Is metformin better than Wegovy?

Metformin and Wegovy are technically approved for different purposes. However, clinical trials have shown that individuals may lose weight and experience improved blood glucose levels on both drugs. In some cases, healthcare providers may prescribe metformin and Wegovy together. 

RELATED: Is it safe to take Ozempic and metformin together?

In a clinical trial called the STEP 2 trial, people with Type 2 diabetes and obesity lost an average of 9.6% of their body weight using semaglutide 2.4 mg, compared to just 3.4% with a placebo over 68 weeks. This treatment also helped improve blood pressure and cholesterol levels. For individuals with obesity or who are overweight without Type 2 diabetes, data from the STEP 1, 3, 4, and 8 trials showed that semaglutide 2.4 mg was associated with average weight losses of 15% to 17% from baseline to week 68.

Some studies have shown that metformin can support weight management, though the effects are generally more modest than Wegovy’s. In a study involving people with prediabetes, participants taking metformin lost an average of 4.6 pounds (2.1 kg) within three years. Over time, they maintained an average weight loss of 5.5 pounds (2.5 kg). About 30% of them lost more than 5% of their body weight in the first year.

Consult a healthcare provider to determine the most appropriate treatment option based on your overall condition. 

Wegovy vs. metformin: Insurance coverage and cost comparison

As a brand-name drug, Wegovy is generally more expensive than metformin and less likely to be covered by insurance plans. Currently, no generic version of Wegovy is available. Some insurance plans may cover Wegovy if it’s prescribed to reduce heart disease-related risks in people who are overweight with heart disease or have obesity and heart disease. Without insurance, the typical cash price is almost $2,000 for a one-month supply.

Unlike Wegovy, metformin is a generic drug that is covered by most, if not all, commercial insurance and Medicare plans. Without insurance, the cost can vary. The average retail price is around $190 for a 30-day supply. 

Patients could save on prescription drugs by using SingleCare coupons. SingleCare offers various discounts that could help reduce the cost of both Wegovy and metformin.

Compare Wegovy vs. metformin cost & coverage
	Wegovy	Metformin
Typically covered by insurance?	No	Yes
Typically covered by Medicare Part D?	No	Yes
Quantity	4 prefilled injection pens	60, 500 mg tablets
SingleCare cost*	$1,196	$4

*Cost with a SingleCare prescription discount card at the time of publication. Drug prices may change and vary by pharmacy.

Wegovy vs. metformin side effects

Wegovy and metformin share several common side effects, especially gastrointestinal ones. Both Wegovy and metformin are known to cause nausea, vomiting, diarrhea, constipation, and indigestion. However, these side effects are also more common at the beginning of treatment and may decrease as the body adjusts to the medication.

Both medications can cause serious side effects that can differ. For example, metformin has specific serious side effects like lactic acidosis, a rare but dangerous build-up of lactic acid in the blood. Wegovy might lead to pancreatitis, which is inflammation of the pancreas and can be severe.

Compare Wegovy vs. metformin side effects
	Wegovy		Metformin
Side effect	Applicable?	Frequency	Applicable?	Frequency
Nausea	Yes	44%	Yes	26%
Vomiting	Yes	24%	Yes	26%
Diarrhea	Yes	30%	Yes	53%
Constipation	Yes	24%	Yes	1%–5%
Indigestion	Yes	9%	Yes	1%–5%
Gas	Yes	6%	Yes	12%
Stomach pain	Yes	20%	Yes	6%
Headache	Yes	14%	Yes	6%
Weakness	No	–	Yes	9%
Fatigue	Yes	11%	No	–
Dizziness	Yes	8%	Yes	1%–5%

Frequency is not based on data from a head-to-head trial. This may not be a complete list of adverse effects that can occur. Please refer to your healthcare provider to learn more.

Source: DailyMed (Wegovy), DailyMed (metformin)

Wegovy and metformin drug interactions

Wegovy and metformin have unique and overlapping drug interactions. They both can interact with other medications that affect blood sugar levels. 

Taking Wegovy or metformin with insulin or insulin secretagogues, such as sulfonylureas, may increase the risk of low blood sugar (hypoglycemia). On the other hand, certain drugs, such as diuretics, calcium channel blockers, corticosteroids, and birth control pills, may increase blood sugar levels, reducing the effectiveness of Wegovy or metformin. 

When metformin is taken with carbonic anhydrase inhibitors, it can increase the risk of a dangerous condition called lactic acidosis. This happens because these inhibitors can cause changes in the body’s acid levels, making metformin’s side effects more severe.

When taking Wegovy with oral medications, the delay in stomach emptying caused by Wegovy might affect how the body absorbs these oral medications.

Compare Wegovy vs. metformin drug interactions
Drug	Drug class	Wegovy	Metformin
Humalog (insulin lispro) NovoLog (insulin aspart) Lantus (insulin glargine)	Insulin	Yes	Yes
Amaryl (glimepiride) Glucotrol (glipizide)	Sulfonylurea	Yes	Yes
Prandin (repaglinide) Starlix (nateglinide)	Glinide	Yes	Yes
Topamax (topiramate) Diamox (acetazolamide) Zonegran (zonisamide)	Carbonic anhydrase inhibitor	No	Yes
Microzide (hydrochlorothiazide) Lozol (indapamide) Hygroton (chlorthalidone)	Diuretic	Yes	Yes
Norvasc (amlodipine) Calan (verapamil) Procardia (nifedipine) Cardizem (diltiazem)	Calcium channel blocker	Yes	Yes
Estinyl (ethinyl estradiol) Aygestin (norethindrone) Prometrium (progesterone)	Estrogens and oral contraceptive	Yes	Yes
Orapred (prednisolone) Deltasone (prednisone) Decadron (dexamethasone)	Corticosteroid	Yes	Yes

Consult a healthcare professional for other possible drug interactions.

Wegovy and metformin drug warnings

Both Wegovy and metformin carry a risk of low blood sugar levels, especially when used with insulin or insulin-boosting drugs. You may need to lower your insulin dose.

In addition, Wegovy may have the following warnings and precautions:

• Thyroid cancer risk: Animal studies suggest Wegovy may cause thyroid tumors. People with a history of thyroid tumors or multiple endocrine neoplasia syndrome type 2 (MEN 2) should not use Wegovy.
• Pancreatitis: Wegovy can cause inflammation of the pancreas. Stop using it if you experience symptoms such as severe abdominal pain, nausea, vomiting, or a rapid heart rate. 
• Gallbladder problems: Wegovy can cause issues with the gallbladder. Monitor for symptoms such as severe abdominal pain, especially in the upper right side, nausea, vomiting, fever, or yellowing of the skin and eyes (jaundice).
• Kidney injury: Wegovy can cause kidney problems. Monitor kidney function if you have severe stomach issues or kidney impairment.
• Eye problems: Wegovy can worsen diabetic eye disease. People with a history of eye problems should be monitored.
• Heart rate increase: Wegovy can increase your heart rate, which may be a problem for people with heart-related conditions. 
• Mental health: Wegovy can cause depression or suicidal thoughts. 

Metformin carries the following warnings and precautions: 

• Lactic acidosis: Metformin can cause a serious condition called lactic acidosis, especially in people with kidney or liver problems or those who drink heavily. Symptoms include weakness, muscle pain, drowsiness, and stomach pain. 
• Vitamin B12 deficiency: Metformin can affect the absorption of vitamin B12 and lead to lower levels of the vitamin.

Allergic reactions are possible with both Wegovy and metformin. Seek immediate medical attention if you experience hives, rash, swelling of the face or throat, or trouble breathing.