💉 Drug Information

They are all medications that work in a similar way — by mimicking hormones in your body to help you feel fuller longer. But here’s how they differ: 

Drug class: 

• Ozempic, Wegovy, and Saxenda are GLP-1 (glucagon-like peptide 1) medications. 

• Zepbound is a dual-action GLP-1 and GIP (short for glucose-dependent insulinotropic polypeptide) medication, which means that it works by activating both the GLP-1 and GIP hormone receptors to regulate your metabolism.

Active ingredient: 

• Ozempic and Wegovy is semaglutide

• Saxenda is liraglutide

• Zepbound is tirzepatide, the same active ingredient as Mounjaro (a FDA-approved medication for type 2 diabetes that is not available through Ro).

How often you take it: 

• Ozempic, Wegovy, and Zepbound are all weekly shots

• Saxenda is a daily shot

How it works:

• Zepbound is the only medication that comes in two dosage forms: single-dose autoinjector pens or single-dose vials that you inject with a syringe and needle. Both contain the exact same active ingredient, tirzepatide.Zepbound pens are available up to the 15 mg dose, while Zepbound single-dose vials are available up to the 5 mg dose.

• Ozempic, Wegovy, and Saxenda are only provided in autoinjector pens.

FDA-approval: 

• Ozempic is FDA-approved for type 2 diabetes, but can be prescribed “off-label” for weight loss — a practice healthcare providers are permitted to do if, in their medical judgment, they believe it is appropriate

• Zepbound, Wegovy, and Saxenda are all FDA-approved for weight loss. 

There are also key differences in how you use the medications, like varying dosing schedules and injection instructions. To learn more, read our Health Guide article. 

Ozempic: Ozempic is approved for type 2 diabetes, although it may be prescribed for weight loss if a provider deems doing so is appropriate. In a clinical trial for Ozempic, people with diabetes who combined weekly injections of 1 mg Ozempic (semaglutide) with a healthy diet and exercise lost an average of 7% of their body weight in 68 weeks (compared to 3.4% with diet and exercise alone). If you are prescribed 2 mg Ozempic (semaglutide) and do not have diabetes, it is possible that you may have a total weight loss percentage closer to the higher results seen in the Wegovy clinical trial (which studied people without diabetes at 2.4 mg of the same active ingredient). Because Ozempic is approved for the treatment of type 2 diabetes, clinical trials using Ozempic in people without diabetes have not been conducted.

Zepbound: Zepbound is approved to treat adult patients with obesity or overweight with a weight-related condition like high blood pressure, type 2 diabetes, or cardiovascular disease. In the main Zepbound clinical trial, people without diabetes who combined a healthy diet and exercise with weekly injections of 15 mg Zepbound (the highest dose available as the autoinjector pen) lost an average of 20% of their body weight in 72 weeks and those who used weekly injections of 5 mg Zepbound (the highest dose available in single-dose vials) lost an average of 15% of their body weight in 72 weeks (compared to 3.1% with diet and exercise alone).

Wegovy: Wegovy is approved for weight loss in people with either obesity or overweight plus a weight-related medical condition, along with a healthy diet and exercise. In the main Wegovy clinical trial, people without diabetes, who combined weekly injections of 2.4 mg Wegovy (semaglutide) with a healthy diet and exercise, lost an average of 14.9% of their body weight in 68 weeks (compared to 2.4% with diet and exercise alone).

Saxenda: Saxenda, like Wegovy, is specifically approved for weight loss. In the main Saxenda clinical trial, people without diabetes, who combined daily injections of 3 mg Saxenda (liraglutide) with a healthy diet and exercise and completed the trial, lost an average of 9.2% of their body weight in 56 weeks (compared to 3.5% with diet and exercise alone).

Everyone responds to these medications differently, and your Ro-affiliated provider will work with you to find a treatment that’s right for you.

Ozempic, Wegovy, and Saxenda come in a prefilled injection pen. You (or someone in your household, if you’re uncomfortable doing so yourself) will administer the injection of semaglutide under the skin of your stomach, thigh, or arm.

Zepbound is the only medication that comes in either single-dose autoinjector pens, or single-dose vials that you inject using a syringe and needle.

Ozempic, Zepbound (pen or vial), and Wegovy are taken once a week. You can take the medication on any day of the week, at any time of day, either with or without food. Once you pick a day, stick with that same day each week to make taking your medication a habit.

Saxenda is a daily injection. You can take the medication at any time of day, either with or without food.

The medications usually start at a low dose and gradually increase to a dose that will remain steady for the remainder of your treatment.

GLP-1 medications come with a risk of potential side effects. The most common side effects are often linked to a dose increase. Over time, these side effects improve once a steady dose is reached.

Some of the most common side effects of GLP-1 medication include:

• Nausea

• Diarrhea

• Vomiting

• Constipation

• Abdominal pain

• Headache

• Fatigue

• Dyspepsia (indigestion)

• Dizziness

• Abdominal distension (bloating)

• Eructation (burping)

• Hypoglycemia in patients with type 2 diabetes

• Flatulence (passing gas)

• Gastroenteritis (upset stomach)

• Gastroesophageal reflux disease (heartburn)

• Hair loss

• Ileus (a decrease or stoppage of intestinal movement)

More severe side effects are rarer, but possible. Serious side effects include:

• Thyroid cancer—The FDA has issued its most serious warning (called a Boxed Warning) that GLP-1s may be associated with a type of thyroid cancer called medullary thyroid carcinoma (MTC). This includes semaglutide which is the active ingredient in Wegovy or Ozempic. So far, this side effect has only been seen in laboratory studies of rodents administered semaglutide, so the risk to humans has not been determined. Semaglutide is contraindicated in patients with a family history of MTC or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).

• Pancreatitis

• Gallbladder disease

• Low blood sugar

• Kidney disease

• Severe allergy (hypersensitivity)

• Vision problems (diabetic retinopathy)

• Rapid heartbeat

• Suicidal thoughts or behaviors

Additionally, Zepbound has been shown to make some medications taken orally less effective. Birth control pills (oral contraceptives) have been shown to be less effective when starting or increasing doses of Zepbound. Medications that require blood test monitoring (like blood thinners) may require more monitoring while taking Zepbound.

For more complete information about Ozempic, see full Important Safety Information.

For more complete information about Zepbound, see full Important Safety Information. 

For more complete information about Wegovy, see full Important Safety Information.

For more complete information about Saxenda, see full Important Safety Information.

The GLP-1s prescribed by Ro-affiliated providers do not contain any common allergens.The active ingredients are:

• Ozempic: Semaglutide

• Zepbound: Tirzepatide

• Wegovy: Semaglutide

• Saxenda: Liraglutide

 Their inactive ingredients are:

• Ozempic: disodium phosphate dihydrate, propylene glycol, phenol, and water

• Zepbound: sodium chloride, sodium phosphate dibasic heptahydrate, and water

• Wegovy: disodium phosphate dihydrate, sodium chloride, and water

• Saxenda: disodium phosphate dihydrate, propylene glycol, phenol, and water

Ro is working with LillyDirect to offer Zepbound single-dose vials, which contain the exact same FDA-approved formulation as Zepbound pens.

There are a few differences between the two options:

• Zepbound pens are prefilled autoinjectors, while the single-dose vials are administered with a syringe and needle.

• Through our integration with LillyDirect, Zepbound vials can be shipped conveniently and directly to you. Zepbound pens can only be fulfilled through your preferred pharmacy.

• Zepbound vials are available in 2.5 mg and 5 mg doses, while Zepbound pens are available up to the 15 mg dose. In clinical trials, patients on the 5 mg dose of Zepbound – the maximum dose available in the single-dose vials – lose on average 15% of their body weight in a year. In clinical trials, patients on the 15 mg dose of Zepbound – the maximum dose available in single-dose pens – lose on average 20% of their body weight in a year.

The medication in Zepbound vials is injected once a week using the syringes and needles included in your medication delivery. Each syringe and needle is meant to be used only once. Do not reuse a syringe or needle. You may inject into your abdomen (at least two inches away from your belly button), upper thigh, or upper arm.

Explore this “how to inject” guide for step-by-step instructions and a helpful video. Please feel free to reach out to your healthcare team if you would like more assistance.

All successful weight loss plans require that you eat and drink fewer calories each day than you burn through activity—and the same is true when it comes to weight management with a GLP-1. When GLP-1s have been studied, participants were told to follow a reduced-calorie diet. That, plus the GLP-1, helped participants lose a significant amount of their body weight over time.

Many weight loss programs feature restrictive diets that cut out long lists of foods. Our approach is different. Rather than making whole food groups off limits, we’ll teach you a new way to look at food—using a few simple guidelines to choose more nutritious foods while finding a balance that’s effective and comfortable for you.

Like a healthy diet, exercise is an essential part of improving your health. In studies evaluating GLP-1s, participants were instructed to perform moderate exercise (like a brisk walk) for 30 minutes a day, five days a week.

But again, for now, focus on getting the hang of taking your GLP-1. Soon, your Ro-affiliated provider will give you tips on how to eat well and get your body moving so you can see the best results.

While a Ro-affiliated provider may offer personalized guidance for each individual, in general, there are no foods to avoid while taking a GLP-1 medication. In fact, our Body Program makes a point to avoid labeling any food as “off-limits,” and instead guides you in finding an approach to food that’s both enjoyable and supports your weight loss goals.

However, you might choose to avoid certain foods on days that your doses are increased. Some gastrointestinal side effects like nausea may occur when your medication’s doses are increased, so you might find that it’s best to avoid foods that make you feel gassy or bloated on days that you’re increasing your dose.

So far, there haven’t been any studies to answer this question.

However, drinking less alcohol is a great way to help you reduce the number of calories you consume each day and could be a helpful part of your weight management plan, if that is why you are taking a GLP-1. With 125–150 calories in one glass of wine or one can of beer, drinking less alcohol can easily help you reach the goal of reducing your daily calories.

GLP-1s can lower blood glucose and using them with other medications that lower blood glucose, such as insulin or sulfonylureas, can cause hypoglycemia or significantly low blood sugar. If you are currently taking one of these medications, you should mention these medications to your Ro-affiliated provider as well as consult with your prescribing provider regarding its use along with a GLP-1.

One of the effects of GLP-1s is decreasing the speed of gastric emptying or the speed that material moves through your gastrointestinal tract. Due to this, it can change the absorption of medications taken by mouth. It’s important to tell your Ro-affiliated provider all of the medications you are currently taking, including prescription, over-the-counter medications, vitamins, and herbal and dietary supplements

If you are on thyroid medication, specifically levothyroxine (a common brand name is Synthroid), GLP-1s can increase the concentration of the levothyroxine in your blood. Please inform your Ro-affiliated provider that you are taking this medication as well as consult with your prescribing provider regarding its use along with a GLP-1.

If you’re on birth control pills (oral contraceptives) or blood thinners (oral anticoagulants), also make sure to inform both your Ro-affiliated provider and your primary care provider before starting Zepbound.  Zepbound has been shown to make some medications taken orally less effective. For birth control pills, the effectiveness is most affected whenever you start a new Zepbound dose, and then improves over time. 

GLP-1s aren’t for everyone. You shouldn’t take a GLP-1 if you have any of the following risk factors:

• Pregnant, possibly pregnant, or planning to get pregnant in the next 3 months; this applies to both those who were assigned male at birth and those who were assigned female at birth who are able to become pregnant

• Breastfeeding

• History of allergic or serious reaction to semaglutide, tirzepatide, or other GLP-1 medications

• Personal or family history of medullary thyroid carcinoma 

• History of multiple endocrine neoplasia syndrome type 2 (MEN2) 

• History of pancreatitis

• History of delayed gastric emptying or gastroparesis 

• History of gallbladder disease or bile duct disease

• History of suicidal ideation or history of suicide attempts 

• History of tachycardia or atrial fibrillation

• Type 1 diabetes

• History of impaired kidney function

• Diabetic retinopathy complications due to type 2 diabetes

All persons, including those who were assigned female at birth and those who were assigned male at birth, who are planning to conceive or conceive with a partner should not take GLP-1s for at least 3 months prior to attempts at conception, including in-vitro fertilization (IVF).

Some religions and cultures mark occasions and holidays by fasting for portions of the day, sometimes over several days or weeks. If you wish to take part in a religious or cultural fast, there is typically no reason for you to stop your medication or change the dose or schedule. It is possible to safely use your medication while fasting. 

There are several things you can do to decrease your chances of feeling unwell while using a GLP-1 during fasts: 

• First, make sure that during non-fasting hours, you consume a healthy number of calories, and drink plenty of water. When you don’t drink water for several hours, there is a risk that this can lead to dehydration, electrolyte imbalance, and in rare instances, kidney problems. Therefore, it is important for you to hydrate yourself during non-fasting hours. 

• If you are on a very low salt diet for medical reasons, consult your primary care or specialty provider about the best approach to hydration during fasting periods. 

• While many traditions consume large and elaborate meals when opening the fast, the best thing to do when taking a GLP-1 is to listen to your body more closely. Because these medications can slow down the passage of food through your system, you may be more comfortable eating smaller portion sizes. 

There is typically no reason why you cannot enjoy festivities or traditional foods in moderation while taking a GLP-1. If you experience any unusual symptoms or side effects, please seek care if urgently needed and reach out to your Ro-affiliated provider.