Rybelsus and metformin are prescription medications. They’re approved by the Food and Drug Administration (FDA) to manage blood sugar levels in adults with type 2 diabetes. Rybelsus is a brand-name drug, and its active ingredient is semaglutide. Metformin is a generic drug, and its brand-name versions include Fortamet and Glumetza.
This article reviews the main similarities and differences between Rybelsus and metformin. If you’re considering treatment with either drug, discussing this information with your doctor can help determine whether one of these treatments may be right for you.
Key differences between Rybelsus and metformin
These are a few of the main differences between Rybelsus and metformin:
- Use in children: Rybelsus is approved for use in adults. Metformin is approved for use in adults as well as certain children. (See “Uses of Rybelsus vs. metformin” below.)
- Dosage: Rybelsus and metformin both come as oral tablets. Metformin is also available as an extended-release oral tablet. (See “Dosages, forms, and administration” below.)
- Side effects: Certain side effects of Rybelsus and metformin differ. For example, Rybelsus may cause a pancreas problem called pancreatitis. Metformin may cause a low level of vitamin B12. (See “Side effects of Rybelsus vs. metformin” below.)
Below are answers to some common questions about Rybelsus and metformin.
Can Rybelsus or metformin be used for weight loss?
Neither Rybelsus nor metformin are approved for weight loss. However, doctors may prescribe either drug off-label for this purpose. With off-label use, a medication approved by the Food and Drug Administration (FDA) is prescribed for a use other than what it’s approved for.
If you’re interested in taking Rybelsus or metformin for weight loss, talk with your doctor. They can help determine if either drug is a good choice for you. Your doctor can also advise you on other ways to manage your weight.
Is Rybelsus a better treatment option than metformin, or vice versa?
It depends. Whether Rybelsus or metformin is a better treatment option for you depends on several factors. These include your medical history, type 2 diabetes treatment goals, and insurance coverage (if you have it).
To learn how Rybelsus and metformin compare for treating type 2 diabetes, see “Effectiveness of Rybelsus vs. metformin” below. You can also talk with your doctor to determine whether one drug or the other is a better option for you.
Here’s information about the generic status of Rybelsus and metformin, as well as details on their active ingredients. Rybelsus is a brand-name drug, and metformin is a generic drug.
|glucagon-like peptide-1 (GLP-1) agonist
* Because metformin itself is a generic drug, it doesn’t have a generic version. Brand-name versions of metformin include Fortamet and Glumetza. If you’d like to learn more about these or other brand-name versions of metformin, talk with your doctor or pharmacist.
Rybelsus or metformin and children
Metformin is approved to treat high blood sugar levels in children ages 10 years and older with type 2 diabetes. The drug is used in combination with diet and exercise. Rybelsus, on the other hand, is approved for use only in adults.
Here’s a quick look at the dosage and administration of Rybelsus and metformin for the conditions both drugs treat.
Dosage for type 2 diabetes
Below is information about dosages of Rybelsus and metformin for treating type 2 diabetes in adults. Milligrams is abbreviated as mg.
|Rybelsus for type 2 diabetes
|Metformin for type 2 diabetes
|• oral immediate-release (IR) tablet
• oral extended-release (ER) tablet
|• 3 mg
• 7 mg
• 14 mg
|oral IR tablet:
• 500 mg
• 850 mg
• 1,000 mg
oral ER tablet:
• 500 mg
• 750 mg
• 1,000 mg
|3 mg to 14 mg
|• oral IR tablet: 850 mg to 2,550 mg
• oral ER tablet: 500 mg to 2,000 mg
|once per day
|• oral IR tablet: 1 to 3 times per day
• oral ER tablet: once per day
If your doctor recommends metformin, they may prescribe metformin IR or metformin ER. IR tablets release the drug into your body right away. ER tablets are specially designed to release the drug slowly into your body over time.
The form of metformin your doctor prescribes may depend on how often you prefer to take the medication and its side effects. For example, metformin ER works for a longer time than metformin IR. Metformin ER can be taken once per day while metformin IR can be taken up to three times per day. Additionally, you’re less likely to experience side effects with metformin ER.
If you have questions about what form of metformin is right for you, ask your doctor.
Both Rybelsus and metformin are used to treat high blood sugar levels caused by type 2 diabetes. These drugs can cause some of the same side effects, as well as some different ones. Some of the side effects reported in clinical trials of these drugs are mentioned below.
For more details about side effects of the two medications, see these side effect articles about Rybelsus and metformin. You can also refer to the prescribing information for Rybelsus, metformin IR, and metformin ER. (IR stands for immediate release. ER stands for extended release. For details, see “Dosages, forms, and administration” above.)
Mild side effects
The following table lists some of the more commonly reported mild side effects of Rybelsus and metformin. The table may also include mild side effects that are less common but that you might have concerns about in some cases.
|Mild side effects
|nausea and vomiting
|mild allergic reaction*
These side effects may be temporary, lasting a few days to weeks. If the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.
* An allergic reaction is possible after taking Rybelsus, but this side effect wasn’t reported in clinical trials. It has occurred since the drug was approved for use. An allergic reaction is also possible after taking metformin, but it’s not clear whether this side effect occurred in clinical trials.
Serious side effects
The following table lists the reported serious side effects of Rybelsus and metformin.
|Serious side effects
|risk of thyroid cancer*
|pancreatitis (inflammation of the pancreas)
|kidney problems, such as acute kidney injury
|low level of vitamin B12
|hypoglycemia (low blood sugar)
|eye problems such as floaters, vision loss, or a detached retina
|severe allergic reaction‡
If you have serious side effects while using Rybelsus or metformin, call your doctor immediately. If the side effects feel life threatening or you believe you’re having a medical emergency, call 911 or your local emergency number right away.
* Rybelsus has a
† Metformin has a boxed warning for this side effect. For more information, see “Precautions of Rybelsus and metformin” below.
‡ An allergic reaction is possible after taking Rybelsus, but this side effect wasn’t reported in clinical trials. However, it has happened since the drug was approved for use. An allergic reaction is also possible after taking metformin, but it’s not clear whether this side effect occurred in clinical trials.
Rybelsus and metformin are both prescribed to manage blood sugar levels in adults with type 2 diabetes. If you’re considering treatment with either drug, you may wonder whether one is more effective than the other for this use.
Prescribing information. Here’s a brief look at the effectiveness of Rybelsus and metformin in clinical trials.
Both Rybelsus and metformin have been found effective for managing blood sugar levels in adults with type 2 diabetes. For details about how these drugs performed in clinical trials, see the prescribing information for Rybelsus, metformin IR, and metformin ER.* Keep in mind that trial results may not apply to your individual health situation.
Treatment guidelines. Another way to determine whether a drug is considered effective is to look at treatment guidelines.
When an organization includes certain drugs in treatment guidelines, this means that research has shown the drug to be safe and effective. Both Rybelsus and metformin are recommended as treatment options for adults with type 2 diabetes in guidelines from the American Diabetes Association. These guidelines do not endorse either drug as better than the other.
Whether Rybelsus or metformin is a better choice for you will depend on several factors, including other medical conditions you may have and your diabetes treatment goals. Your doctor can discuss these factors with you. They can also help determine whether Rybelsus or metformin (or both, as the drugs can be used together) are right for you.
* IR stands for immediate release. ER stands for extended release. For details, see “Dosages, forms, and administration” above.
How much Rybelsus or metformin costs depends on the treatment plan your doctor prescribes, your insurance plan, and your pharmacy. You can visit Optum Perks for price estimates of Rybelsus and metformin.
Rybelsus is a brand-name drug that isn’t available as a generic. Metformin, on the other hand, is a generic medication. Brand-name forms of metformin include Fortamet and Glumetza. Brand-name medications are often more expensive than generics.
Rybelsus and metformin may not be right for you if you have certain medical conditions or other factors that affect your health. The two drugs share some of the same precautions, but they also have different ones. Some of these precautions are mentioned below.
Risk of thyroid C-cell tumors
Rybelsus has a
Thyroid C-cell tumors are masses of cancerous tissue in the thyroid gland. They begin to form in cells known as C cells.
Rybelsus and similar drugs increased the risk of certain thyroid cancers in animal studies, including a type called medullary thyroid cancer (MTC). However, it’s important to note that animal studies don’t always predict what effects a medication will have when people take it. It’s not known whether Rybelsus increases the risk of thyroid cancer in people.
Symptoms of thyroid cancer
Symptoms of thyroid cancer can include:
- abnormal growth or lump in your neck
- hoarse voice
- shortness of breath
- problems swallowing
Steps your doctor may take
Because of this risk, doctors typically won’t prescribe Rybelsus if you or a family member has or has had MTC. They’ll also typically avoid prescribing Rybelsus if you have had a type of cancer called multiple endocrine neoplasia syndrome type 2 (MEN2).
If your doctor does prescribe Rybelsus, they’ll monitor you closely for symptoms of thyroid cancer.
Since metformin was approved for use, there have been rare reports of lactic acidosis in people taking the drug. Lactic acidosis is a condition caused by a buildup of lactic acid in your blood. (Lactic acid is a type of chemical your body makes.) Lactic acidosis is life threatening and requires immediate treatment in the hospital.
Symptoms of lactic acidosis
Symptoms of lactic acidosis include:
- feeling weak or generally unwell
- unusual muscle pain
- difficulty breathing
- feeling cold, particularly in your arms or legs
- pain in your abdomen
- nausea and vomiting
- low blood pressure
- slow or irregular heart rate or rhythm
Risk factors for lactic acidosis due to metformin
Most cases of lactic acidosis occurred in people taking metformin who also had a kidney problem, such as chronic kidney disease. Other factors that can increase your risk of lactic acidosis during metformin treatment include:
- being age 65 years or older
- receiving a contrast dye* that contains iodine prior to an imaging procedure, such as a CT scan or another type of X-ray
- having a restricted food or fluid intake, such as prior to surgery
- excessive alcohol consumption
- having a liver problem, such as hepatitis
- having congestive heart failure
If you think you’re having symptoms of lactic acidosis while taking metformin, talk with your doctor immediately. They may recommend that you go to the emergency room and stop taking metformin right away.
* A contrast dye is a substance that helps images appear more clearly. It’s often swallowed or injected.
In addition to boxed warnings, Rybelsus and metformin have other warnings.
If any of the following medical conditions or other health factors are relevant to you, talk with your doctor before taking Rybelsus or metformin.
|if you’ve had an allergic reaction to either drug or any of its ingredients
|if you’re pregnant or thinking about becoming pregnant
|if you’re breastfeeding or thinking about breastfeeding
|if you have a kidney problem, such as acute kidney injury
|if you have a pancreas problem, such as pancreatitis
|if you have diabetic retinopathy
|if you have a heart problem, such as heart disease
|if you have a liver problem
Switching between Rybelsus and metformin is possible.
If you’d like to know more about switching between Rybelsus and metformin, talk with your doctor. They can give you additional details and help determine the best course of action for your personal situation. Even if two drugs treat the same condition or are in the same drug class, your body can still respond differently.
It’s important that you do not stop, start, or switch any of your drug treatments without your doctor’s recommendation.
Some key points to remember when comparing Rybelsus and metformin include:
- Dosage. Rybelsus comes in one form: an oral tablet. Metformin is available in two forms: an oral tablet and an extended-release oral tablet. Extended release means the tablet is specially designed to release the drug slowly into your body over time.
- Side effects. Some side effects of Rybelsus and metformin are alike, and some are different. For example, Rybelsus may cause pancreatitis (inflammation of the pancreas), and metformin may cause a low level of vitamin B12.
- Use in children. Rybelsus is for use only in adults. Metformin is for use in adults as well as children ages 10 years and older.
If you’d like to learn more about Rybelsus or metformin, talk with your doctor or pharmacist. They can help answer any questions you have about similarities and differences between the drugs. They can also help determine whether one drug or the other might work well for you.
Note: For more information about type 2 diabetes, see our diabetes hub.
Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.