What you’ll learn:
- Semaglutide is the active ingredient in Ozempic®, Wegovy®, and Rybelsus®. These medications are prescribed for weight loss and to treat type 2 diabetes.
- Semaglutide causes several common side effects like nausea, digestive changes, and fatigue. It is also associated with some rare but severe issues that people should consider before starting a medication that contains it.
- All scheduled medications will be started at the lowest dose and slowly increased to reduce the risk of side effects.
If you haven’t heard of semaglutide, you’ve probably heard of a medication that contains it: Ozempic®. While Ozempic® is widely known for its role in weight loss, it’s actually FDA-approved to treat type 2 diabetes and often prescribed off-label for weight management. Semaglutide is also the active ingredient in two other medications: Wegovy®, which is FDA-approved for weight loss and to reduce the risk of major cardiovascular events, and Rybelsus®, an oral, pill-based version approved for type 2 diabetes. All three medications work similarly and tend to produce similar side effects, some of which are important to understand before starting treatment.
Semaglutide works by mimicking a naturally occurring hormone in your body called GLP-1 (glucagon-like peptide-1). This hormone helps regulate blood sugar, slows digestion, and promotes a feeling of fullness. By enhancing the effects of GLP-1, semaglutide helps you eat less, feel more satisfied, and manage your blood sugar more effectively. These changes affect several key systems in your body, including how quickly your stomach empties and how much insulin your pancreas releases. As your digestion slows and your appetite decreases, you may experience side effects like nausea, bloating, stomach pain, indigestion, or constipation.
In this guide, we’ll walk you through exactly how semaglutide works in the body, what side effects to expect, and how your doctor may adjust your dose to minimize discomfort and support long-term success. We’ll also explain a few serious, but rare, risks, so you know what to watch for and when to reach out for help.
Whether you’re starting semaglutide, adjusting your dose, or exploring your options, understanding how it works can help you feel more confident, more prepared, and more in control of your health journey.
How semaglutide affects your body
When you take semaglutide, you’re giving your body a little extra of that GLP-1 signal. The medication helps slow down how quickly food leaves your stomach, which means you feel full longer after eating. It also helps reduce the release of another hormone called glucagon, which normally tells your liver to release stored sugar. Together, these effects help keep your blood sugar steadier and your appetite in check.
For many people, this means fewer food cravings, smaller portion sizes, and a natural shift toward eating less without feeling like you’re forcing it. These changes not only support weight loss but can also help with managing blood sugar levels, especially for those with type 2 diabetes.
Semaglutide comes in two main forms: a once-weekly injection (Ozempic® and Wegovy®) or a daily pill (Rybelsus®). Your healthcare provider will help you decide which option and dosage are the best fit for your health goals.
When are side effects most likely with semaglutide?
Side effects with semaglutide are most common when you’re first starting the medication or increasing to a higher dose. That’s why the dosing schedule follows a slow, step-up approach—starting low and gradually increasing over several weeks. This escalation strategy is designed to help your body adjust, making side effects easier to manage. If side effects do show up, they often fade as your body gets used to each new dose. And, if you’re comfortable at a certain dose and getting the desired results, there’s no reason to move to the next dose.
Common side effects of taking semaglutide
Here’s a closer look at the most common side effects reported with semaglutide by the highest doses of Ozempic®, Wegovy®, and Rybelsus®, and some simple ways to navigate them. Remember all three of these medications contain the same ingredient—semaglutide. With the oral version, Rybelsus, less of the medication makes it into the body because it must go through the digestive system first.
Here are the doses of semaglutide available with each medication for reference:
- Ozempic®: 0.25 mg, 0.5 mg, 1 mg, 2 mg
- Wegovy®: 0.25 mg, 0.5 mg, 1 mg, 1.7 mg, 2.4 mg
- Rybelsus®: 3 mg, 7 mg, 14 mg
Gastrointestinal issues
Gastrointestinal side effects are some of the most commonly reported changes with semaglutide. The table below highlights how often these side effects have been reported in clinical trials across different semaglutide medications, and some tips on how to manage them.
| Symptom | The highest dose of Wegovy® (2.4 mg dose) | The highest dose of Ozempic® (1 mg dose) | The highest dose of Rybelsus® (14 mg oral dose) | What can help |
|---|---|---|---|---|
| Nausea | 44% | 20% | 20% | Eating small, low-fat meals helps manage nausea. Avoiding greasy or very spicy foods is also a widely used strategy that may make symptoms easier to handle. |
| Vomiting | 24% | 9% | 8% | Clear fluids and bland foods are often recommended to help soothe an upset stomach. |
| Diarrhea | 30% | 9% | 10% | Many healthcare professionals suggest focusing on hydration and choosing low-fiber foods to help your digestion recover during bouts of diarrhea. |
| Constipation | 24% | 3.1% | 5% | Doctors commonly recommend adding fiber slowly to your diet, staying well-hydrated, and incorporating regular movement to support healthy digestion and ease constipation. |
| Abdominal pain | 20% | 5.7% | 11% | Sticking with clear fluids and taking a break from solid foods for a few hours is a widely used approach for easing abdominal pain. |
| Dyspepsia | 9% | 2.7% | 0.6% | Try to avoid foods that trigger discomfort, reduce stress, and skip meals close to bedtime. If you have reflux, raising the head of your bed may also help. |
| Heartburn/GERD | 5% | 1.5% | 2% | Experts say lifestyle changes like losing weight, quitting smoking, and elevating your head during sleep can ease GERD symptoms. Avoiding large or late meals may also help. |
If these symptoms feel hard to manage or continue longer than expected, it’s a good idea to check in with your healthcare provider. They may recommend adjusting your dose schedule, slowing dose increases, or offering additional strategies for relief. For extra support, Noom’s GLP-1 Companion provides personalized tips and guidance to help you navigate side effects and stay on track with your plan.
Other symptoms
Along with digestive changes, some people taking semaglutide report shifts in energy, sleep, or mood, especially during the first few weeks of treatment or when increasing the dose. The table below highlights how often some of these symptoms were reported in clinical trials, along with strategies that may help make them easier to manage.
| Symptom | Wegovy® (2.4 mg dose) | Ozempic® (1 mg dose) | Rybelsus® (14 mg oral dose) | What can help |
|---|---|---|---|---|
| Headache | 14% | 6-7% | 5% | Healthcare professionals recommend staying well-hydrated throughout the day and taking breaks from screens to ease discomfort. |
| Fatigue | 11% | Happened in >0.4% of trial participants | Rate not reported | Common tips for reducing fatigue include having balanced meals and prioritizing good sleep habits. Healthcare experts also encourage light activity to boost energy. |
| Dizziness | 8% | Happened in >0.4% of trial participants | Rate not reported | Keeping up with fluids and avoiding sudden movements are usual tips for managing dizziness. Standing up or moving slowly can help prevent feeling lightheaded. |
If you’re noticing any of these changes, it’s a good idea to check in with your healthcare provider. They can help you find ways to manage what you’re feeling and find the right kind of support.
Metabolic and cardiovascular symptoms
Some people taking semaglutide may experience side effects that affect blood sugar levels or heart rate. Here are a few things to watch for:
- Signs of low blood sugar (hypoglycemia): Symptoms like shakiness, fatigue, dizziness, or confusion can sometimes indicate that your blood sugar has dropped too low. This tends to be more common if you’re also taking insulin or medications like sulfonylureas for type 2 diabetes.
- Increased heart rate: Some people report a rapid or pounding heartbeat, even without an obvious trigger. Clinical trials of semaglutide at higher doses have shown that resting heart rate may rise by 1 to 4 beats per minute on average, with some participants experiencing an increase of 20 bpm or more.
If you notice any of these symptoms, it’s a good idea to check in with your healthcare provider. They can help monitor how your body is adjusting and make changes to your treatment plan if needed to keep things on track.
Other potential side effects of semaglutide
Some potential side effects of semaglutide aren’t directly caused by the medication itself but may happen as a result of weight loss or the way semaglutide works in the body. Here’s a closer look at what people frequently ask about—and what may help if you notice these changes:
| Potential side effects | Why it happens | What to do according to healthcare experts |
|---|---|---|
| Muscle loss or loss of muscle tone | Rapid weight loss can sometimes lead to a reduction in lean muscle, especially without enough protein intake or strength training. | Focus on eating enough protein and adding resistance training to your routine. Both help maintain muscle mass and support a healthy metabolism. |
| Facial volume loss (“Ozempic face”) | Weight loss can lead to a reduction in facial fat, which may make features appear more hollow or sunken. | Stay hydrated and talk to your provider about finding a steady, sustainable pace for weight loss. |
| Feeling cold more often | A lower body weight and reduced calorie intake can slow metabolism slightly, making it harder for the body to retain heat. | Keep moving throughout the day to boost circulation. Dressing in layers and staying active can also help you stay warm. |
| Hair thinning or shedding | Rapid weight loss can place stress on the body, sometimes leading to temporary hair loss. Nutrient gaps may also play a role. | Make sure your diet includes enough protein, iron, and other key nutrients that support hair health. |
| Mood shifts, anxiety, or depression | Some people report emotional changes while on semaglutide, though the exact cause isn’t fully understood. Weight loss, hormonal shifts, or medication effects may contribute. | Stay mindful of how you’re feeling emotionally. If you notice mood changes, talk to your healthcare provider—they can help you find the right kind of support. If you’re in crisis or need immediate help, contact the Suicide & Crisis Lifeline by calling 988. |
| Insomnia | Some people notice it’s harder to fall asleep or stay asleep, especially when their dose changes. May be linked to the mood shifts mentioned above, as emotional changes can affect sleep patterns | Stick to a consistent sleep schedule and avoid caffeine or heavy meals before bed. A calming routine, like reading or a warm bath, can also help you wind down. |
| Changes in fertility | Weight loss can improve hormone balance and ovulation, which may increase fertility, especially in people with PCOS or irregular cycles. | If pregnancy is part of your plans—or if you’re looking to prevent it—check in with your healthcare provider to talk through the best options for you. Semaglutide should be stopped at least two months before trying to conceive. |
Being aware of these potential side effects can help you feel more prepared. If something feels off, your healthcare provider can help you explore what’s going on and recommend next steps.
Do females experience different side effects with semaglutide?
Semaglutide medications don’t cause side effects that are exclusive to females, but some experiences may show up more often or feel a bit different due to hormonal changes and the way weight loss can affect the body. Here are a few things to keep in mind:
- Possible benefits for polycystic ovary syndrome (PCOS): According to a study, nearly 80% of people with PCOS and a BMI of 30 or higher who responded to semaglutide treatment noticed more regular periods after six months.
- Stronger side effects for some: Research suggests that females may be more likely than males to experience specific side effects with GLP-1 medications like semaglutide, especially gastrointestinal symptoms like nausea or vomiting.
- Changes in menstrual cycles: Some people report irregular periods or spotting while using semaglutide. Rapid weight loss can influence estrogen levels, which may temporarily disrupt your cycle.
- Fertility changes: Weight loss can lead to more regular ovulation, which may increase the chances of becoming pregnant. But remember, GLP-1 medications like semaglutide need to be stopped two months before trying to conceive.
- Birth control considerations: GLP-1 medications like semaglutide can slow digestion, which may impact how oral birth control pills are absorbed. Until more conclusive research is done, it’s recommended to have a non-oral option or backup contraception.
If you notice changes in your cycle or are thinking about becoming pregnant, it’s a good idea to bring it up with your healthcare provider. They can help you decide what’s safest and talk through your next steps.
Semaglutide injection site reactions
For injectable semaglutide medications like Ozempic® and Wegovy®, mild skin reactions at the injection site are fairly common. These side effects are usually temporary and tend to improve with a few simple adjustments to your injection routine.
Here’s what you might experience:
- Redness or swelling: A small red or raised area may appear where you were injected, often within the first few hours. This typically fades on its own within a day or two.
- Itching or irritation: Some people notice mild itching around the injection site. While it can feel uncomfortable, it usually doesn’t last long. Avoid scratching to prevent further irritation.
- Tenderness or bruising: Mild pain or bruising can happen, often depending on needle placement. Rotating injection spots can help reduce the chances of this happening repeatedly in the same area.
A few tips from medication guides for Ozempic® and Wegovy® include:
- Change injection sites each week, rotating between common spots, including the abdomen, thigh, or upper arm.
- Clean the skin with an alcohol swab and let it dry completely before injecting.
- Use a new needle each time and make sure to dispose of it properly.
- Inject slowly and avoid rubbing the area right after your shot.
If you notice redness or swelling that sticks around, pain that gets worse, or any signs of infection like warmth, pus, or spreading redness, check in with your healthcare provider. Otherwise, these reactions are typically mild and manageable with a few minor adjustments.
Side effects of stopping semaglutide
Semaglutide is meant to support long-term weight or blood sugar management, so stopping it without a plan can bring some unexpected changes. Here’s what may happen if you pause or discontinue treatment:
- Hunger will increase: Appetite and thoughts about food often return once the medication is stopped.
- Some weight regain is possible: If healthy habits like balanced eating and regular movement aren’t firmly in place, regaining weight is common.
- Tapering may help: Slowly easing off the medication with your provider’s guidance can make the transition smoother.
- Habits still matter: Staying active and having accountability tools like Noom can help maintain progress after stopping.
Before making any changes, check in with your healthcare provider to plan the best approach for your long-term success.
Severe side effects and warnings for semaglutide
Semaglutide can be a helpful tool for managing weight or blood sugar, but it comes with some risks. Serious side effects aren’t common, but knowing what to watch for can help you stay informed and prepared.
First, semaglutide carries an FDA boxed warning about a possible risk of thyroid C-cell tumors found in animal studies. While it’s unclear if this applies to humans, you should avoid semaglutide if you or your family has a history of medullary thyroid carcinoma (MTC) or MEN 2. Always share this with your healthcare provider before starting treatment.
Here are some other potential rare side effects. If you experience any signs of these, get immediate medical attention:
- Pancreatitis: Ongoing stomach pain that spreads to your back, especially with nausea or vomiting, could signal pancreatitis. Stop the medication and get medical care right away.
- Gallbladder issues: Pain in the upper right abdomen, fever, nausea, or yellowing of the skin or eyes may point to gallstones or gallbladder inflammation.
- Kidney problems: Vomiting or diarrhea can lead to dehydration, which may strain your kidneys. Look out for fatigue, swelling, or less frequent urination.
- Severe allergic reactions: Though rare, symptoms like facial swelling, trouble breathing, or a full-body rash need emergency attention.
- Low blood sugar (hypoglycemia): This reaction is more likely if you’re also on insulin or sulfonylureas for type 2 diabetes. Signs of hypoglycemia include shakiness, sweating, confusion, or fainting.
- Heart rate changes: If your heart feels unusually fast or pounding while at rest, let your provider know.
Most people will not experience these side effects, but it’s important to stay aware. If something feels wrong or you think you’re having a serious reaction, get medical care immediately.
Who shouldn’t take semaglutide?
Semaglutide isn’t right for everyone. Certain health conditions and risk factors may make this medication unsafe.
You should not take semaglutide if:
- You or a family member has a history of medullary thyroid carcinoma (MTC) or MEN 2.
- You have a known allergy to semaglutide or any of its ingredients.
Your doctor will decide if semaglutide is right for you if you have a history of:
- Pancreatitis.
- Serious digestive issues like gastroparesis, since semaglutide slows stomach emptying and may worsen symptoms.
You should also not take semaglutide if you are pregnant or breastfeeding.
Always talk with your healthcare provider about your medical history before starting semaglutide. They can help you decide if it’s the right option based on your needs and goals.
For more information, visit the safety pages for Wegovy®, Ozempic®, and Rybelsus®.
Comparing semaglutide to other GLP-1 drugs
If you’re exploring GLP-1 medications, it’s helpful to understand how semaglutide stacks up against other options like tirzepatide, liraglutide, and dulaglutide. While all these medications can have similar side effects, they differ in how often they are experienced.
Side-effect frequency comparison
Here’s a quick look at how often people report common side effects at the highest studied doses of each medication:
| Medication (dose) | Nausea | Vomiting | Diarrhea | Constipation | Dyspepsia | Key differences |
|---|---|---|---|---|---|---|
| Semaglutide (2.4 mg) | 44% | 24% | 30% | 24% | 9% | Higher rates of nausea, vomiting, diarrhea, and constipation, especially at full weight-loss doses. |
| Tirzepatide (15 mg) | 28% | 13% | 23% | 11% | 10% | Lower nausea and constipation; nausea and diarrhea are more commonly reported. |
| Liraglutide (3 mg) | 39% | 16% | 21% | 19.4% | 10% | Fewer GI side effects than semaglutide; less nausea and vomiting. |
| Dulaglutide (4.5 mg) | 16% | 9% | 11% | Not reported | 3% | Lowest GI side effect rates; less constipation and abdominal discomfort. |
No GLP-1 medications are free from side effects, but they can be managed. The right choice often depends on your health history, how your body responds, and what feels sustainable for your lifestyle. Talking it through with your healthcare provider can help you find the medication that best fits your plan.
Stay informed, supported, and on track
Semaglutide medications can be powerful tools for long-term weight management, but understanding how they work—and what to expect along the way—makes a big difference. Many people experience side effects like nausea, constipation, or fatigue early on, though these often ease as the body adjusts to the medication. If something doesn’t feel right, checking in with your healthcare provider can help you stay comfortable and keep your plan on track.
While serious side effects are rare, knowing the risks and staying aware of any changes in how you feel helps you stay ahead. Semaglutide isn’t the right fit for everyone, especially for people who are pregnant, breastfeeding, or have certain health conditions, so having the right guidance from the start is key.
If you qualify for Noom Med, you’ll work directly with a clinician who can help you explore medication options, manage side effects, and adjust your plan as needed. With the proper support in place, you can feel more confident in your journey toward your health goals.
Note: Ozempic® and Rybelsus® are not FDA-approved for treating obesity or weight loss.
