GLP-1 Side Effects: What to Expect and How to Manage Them

# Glucagon-like peptide-1 (GLP-1) side effects: What to expect and how to manage them Glucagon-like peptide-1 (GLP-1) medications have helped millions of people lose weight and manage blood sugar—but the side effects can catch you off guard if you don't know what's coming. Nausea, changes in appetite, and digestive shifts are part of the adjustment process for most people, and they're usually temporary. This guide covers the most common GLP-1 side effects, which ones are serious, and practical strategies to manage symptoms while your body adapts. ## What are GLP-1 medications and how do they work Knowing how GLP-1 agonists work in your body helps explain why certain side effects happen in the first place. If you're already familiar with GLP-1 medications and want to jump straight to side effects, skip to the next section. GLP-1 stands for glucagon-like peptide-1, a hormone your body naturally makes after you eat. This hormone tells your brain you're full, slows down how fast food leaves your stomach, and helps keep blood sugar steady. GLP-1 agonists are medications that mimic this hormone, amplifying its effects to support weight loss and blood sugar control. Here's what happens when you take a GLP-1 medication: * **Slows stomach emptying:** Food stays in your stomach longer, which helps you feel full but can also cause nausea * **Signals fullness to the brain:** Reduced hunger cues mean you naturally eat less * **Regulates blood sugar:** Improved metabolic function supports overall health Most GLP-1 medications come as weekly or daily injections, though oral versions are currently available. The FDA has approved GLP-1 receptor agonists for both type 2 diabetes and weight management in people with a BMI of 30 or higher, or 27 or higher with weight-related health conditions. Because GLP-1s slow digestion, gut-related side effects are extremely common. Once you understand the mechanism, the side effects make a lot more sense. ## Common side effects of GLP-1 medications GLP-1 side effects primarily involve the gut. Nausea, vomiting, diarrhea, and constipation are by far the most common, and they usually ease as your body adjusts. However, side effects can temporarily worsen when doses increase. This section covers what most people experience. For serious or rare side effects, see "Serious GLP-1 side effects and risks" below. ### Nausea and vomiting Nausea is often the first thing people notice. Because GLP-1s slow gastric emptying, food sits in your stomach longer than usual, which can feel uncomfortable after meals. For most people, nausea is strongest during the first few weeks and fades over time. Eating smaller, lower-fat meals tends to help. ### Diarrhea and constipation It might seem odd that both diarrhea and constipation can happen, but GLP-1s affect gut motility in complex ways. Both can occur at various points during treatment, with timing varying between individuals. Staying hydrated and gradually adding fiber can help with both. Individual responses vary quite a bit depending on diet and biology. ### Loss of appetite Reduced appetite is actually the intended effect, not just a side effect. Your brain receives stronger fullness signals, so you naturally want to eat less. The key is telling the difference between healthy appetite reduction and concerning food aversion. Even with a smaller appetite, balanced nutrition still matters. If eating enough to meet basic nutritional needs becomes difficult, that's worth bringing up with a clinician. ### Injection site reactions Mild redness, swelling, or itching where you inject is common and usually goes away on its own. Rotating injection sites between your abdomen, thigh, and upper arm can help minimize irritation. ### Headaches and dizziness Headaches and dizziness may relate to blood sugar changes or simply eating fewer calories than before. Both are usually mild and tend to fade as your body adjusts. Staying well-hydrated often helps. ### Fatigue and low energy Feeling tired during the first few weeks isn't unusual. When you're eating less, your body is adjusting to different energy intake. Prioritizing protein and balanced nutrition can help maintain energy levels. Fatigue that sticks around beyond the initial adjustment period is worth mentioning to your clinician. ### How long GLP-1 side effects typically last Most common side effects improve within the first four to eight weeks of treatment. They may temporarily return when your dose increases, which is why most treatment protocols use gradual dose escalation. Timelines vary from person to person. Some people experience minimal side effects from the start, while others take longer to adjust. If side effects persist or significantly impact daily life, a clinician can help troubleshoot. ## What is Ozempic face You may have heard "Ozempic face" used to describe facial changes some people notice during significant weight loss. The term refers to a hollowed or gaunt appearance, with more visible cheekbones, deeper lines, or sagging skin around the face and neck. Here's what's important: this isn't a direct medication side effect. It's related to rapid weight loss from any cause. When weight drops quickly, facial fat decreases, and skin may not retract as fast as the underlying tissue changes. Signs sometimes described as Ozempic face include: * Hollowed or sunken appearance around cheeks and eyes * More visible lines and wrinkles * Sagging or loose skin on the face and neck * Thinning lips Whether someone notices facial changes depends on age, genetics, how much weight is lost, and how quickly. Many people don't experience significant changes at all. Adequate protein intake, hydration, sun protection, and more gradual weight loss may help. ## Other physical changes from GLP-1 treatment Beyond gut-related effects, some people notice changes in their skin or hair during treatment. Most of the time, the changes relate to weight loss itself rather than the medication directly. | Physical change | Likely cause | Supportive approaches | | --- | --- | --- | | Hair thinning | Rapid weight loss, possible nutritional gaps | Adequate protein, discuss with clinician | | Dry skin | Reduced fat intake, dehydration | Hydration, moisturizing, balanced nutrition | | Loose skin | Significant weight loss | Gradual weight loss, strength training | Hair thinning, sometimes called telogen effluvium, can occur with any significant weight change. It's usually temporary and stabilizes once weight loss slows and nutrition is optimized. If you notice concerning changes, discussing them with your clinician can help identify whether nutritional adjustments or other approaches might help. ## Long-term side effects of GLP-1 medications Many people wonder about GLP-1 long-term side effects, especially as more people use the medications for weight management. If you're weighing the decision to start GLP-1 treatment, here's what current evidence suggests. GLP-1 receptor agonists have been used for type 2 diabetes management for over a decade, which provides some long-term safety data. For weight loss specifically, the research timeline is shorter, and studies continue to track outcomes over extended periods. One area of ongoing attention is muscle mass preservation. Because GLP-1s reduce appetite significantly, adequate protein intake and strength training become especially important for maintaining muscle during weight loss. Some people may experience persistent GI symptoms, though this varies considerably. Regular check-ins with a health care provider during extended use help catch any concerns early. Long-term experiences differ significantly between individuals. ## Serious GLP-1 side effects and risks Serious side effects are uncommon, but knowing the warning signs helps you recognize when to seek medical attention. ### Pancreatitis Pancreatitis is inflammation of the pancreas. Warning signs include severe abdominal pain that may radiate to your back and persistent vomiting. This is rare but requires immediate medical attention. People with a history of pancreatitis may want to discuss individual risk with a clinician before starting treatment. ### Gallbladder problems Rapid weight loss from any cause increases the risk of gallstones. GLP-1s may also affect gallbladder function independently. Warning signs include severe abdominal pain (especially in the upper right area), nausea, and fever. A lower-fat diet may help reduce risk. ### Thyroid tumors GLP-1 medications carry an FDA boxed warning based on animal studies showing thyroid C-cell tumors in rodents. This hasn't been confirmed in humans, but monitoring is important. Warning signs include a lump or swelling in the neck, difficulty swallowing, or persistent hoarseness. People with personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) are advised not to take GLP-1 receptor agonists. ### Severe allergic reactions Signs of a serious allergic reaction include swelling of the face or throat, difficulty breathing, and severe rash. Allergic reactions are rare but require immediate emergency care. Mild injection site reactions are different from systemic allergic reactions. ### Kidney problems Dehydration from vomiting or diarrhea can affect kidney function, particularly for people with pre-existing kidney conditions. Staying hydrated, especially when experiencing GI side effects, is important. Warning signs include decreased urination, swelling in legs or ankles, and unusual fatigue. ## Who may not be a candidate for GLP-1 medications While GLP-1 medications work well for many people, certain health histories may make them unsuitable. A thorough medical evaluation helps determine whether GLP-1s are appropriate for you. ### Personal or family history of medullary thyroid carcinoma Due to the thyroid tumor findings in animal studies, people with personal or family history of medullary thyroid carcinoma are advised not to take GLP-1 receptor agonists. The same applies to people with MEN 2. ### History of pancreatitis People with a history of pancreatitis may have elevated risk. Clinicians can help weigh risks and benefits on an individual basis, and close monitoring is essential if treatment is considered. ### Pregnancy and breastfeeding GLP-1 medications aren't recommended during pregnancy. People who may become pregnant benefit from discussing timing and contraception with their clinician. Limited data exists on breastfeeding, so discussing options with a health care provider is important. ### Severe gastrointestinal conditions Conditions like gastroparesis (delayed stomach emptying) may worsen with GLP-1 treatment. Inflammatory bowel disease or severe GI disorders require careful evaluation. Clinicians can assess whether GLP-1s are appropriate based on GI health history. ## How to manage GLP-1 side effects Most GLP-1 side effects can be effectively managed with practical adjustments. If you're already taking a GLP-1 and dealing with side effects, here are approaches that can help. ### 1\. Eat smaller meals more frequently Large meals can overwhelm a digestive system that's processing food more slowly. Smaller, more frequent meals reduce the burden on your stomach while helping you maintain adequate nutrition. Focus on nutrient-dense foods, and consider keeping meals lower in fat, which tends to be easier to digest. ### 2\. Stay hydrated and prioritize fiber Adequate hydration helps with both diarrhea and constipation. For constipation, gradually adding fiber-rich foods can support regularity. For diarrhea, bland foods initially, then slowly reintroducing fiber, often helps. Sipping fluids throughout the day rather than drinking large amounts at once tends to be gentler on the stomach. ### 3\. Avoid foods that trigger symptoms Common triggers include fried foods, very spicy dishes, and carbonated beverages. Keeping a simple food diary can help identify personal triggers, since what bothers one person may be fine for another. Foods to consider limiting: * Fried and greasy foods * Very spicy dishes * Carbonated drinks * Large portions of high-fat foods ### 4\. Time GLP-1 injections strategically Some people find that taking their injection at certain times, like before bed, helps minimize daytime nausea. Consistency in timing can also help your body adjust. Your clinician can help determine optimal timing based on your schedule and symptoms. ### 5\. Start low and increase doses gradually The "start low, go slow" approach gives your body time to adjust, minimizing side effects. Patience often leads to better tolerance. Rushing to increase doses can intensify side effects unnecessarily. Clinicians can adjust the titration schedule if side effects are significant. ### 6\. Give your body time to adjust Many side effects improve within the first several weeks. Avoid the temptation to stop too quickly if side effects are manageable. Consistent communication with your health care provider helps navigate the adjustment period. ## When to contact your health care provider While most side effects are manageable at home, certain symptoms warrant prompt attention. **Seek immediate medical attention for:** * Severe abdominal pain that doesn't go away * Signs of allergic reaction (swelling of face or throat, difficulty breathing) * Symptoms of pancreatitis (severe pain radiating to back, persistent vomiting) * Signs of severe dehydration **Contact your clinician soon for:** * Side effects that don't improve after several weeks * Side effects that significantly impact daily life or ability to eat adequately * New or worsening symptoms after a dose increase * Any concerning changes you're unsure about Reaching out is always appropriate if something feels wrong. Adjusting doses or timing can often resolve persistent issues. ## How expert support can help you navigate GLP-1 treatment Having access to clinicians who specialize in weight care can make a meaningful difference in managing side effects and achieving sustainable results. Medication works best as one part of comprehensive weight care, combined with lifestyle guidance and ongoing support. Clinicians trained in weight management understand how to adjust treatment based on individual response. They can help troubleshoot side effects, optimize dosing, and ensure you're getting the nutrition and support you need throughout your journey. Found is among the largest medically-supported telehealth weight care platforms in the country, having served more than 250,000 members to date. To discover your MetabolicPrint™ and start your journey with Found, [take our quiz](https://clinic.joinfound.com/health-assessment-survey/welcome). _Individual results may vary._ ## FAQs about GLP-1 side effects ### What happens when you stop taking GLP-1 medications for weight loss? When GLP-1 treatment stops, appetite typically returns to previous levels and weight regain is common without ongoing lifestyle changes. This is why many clinicians recommend combining medication with sustainable habit changes for lasting results. ### Do side effects differ between specific GLP-1 medications? While all GLP-1 receptor agonists share similar side effect profiles, individual experiences can vary between specific medications based on dosing schedule and formulation. A clinician can help determine which medication may be best tolerated based on personal health history. ### Can GLP-1 medications interact with other prescription medications? GLP-1 medications can interact with certain other medications, particularly those affected by delayed stomach emptying. Always share a complete medication list with your clinician before starting treatment. ### Does taking GLP-1 medication cause hair loss? Hair thinning reported by some people taking GLP-1s is typically related to rapid weight loss rather than the medication itself. This phenomenon, called telogen effluvium, can occur with any significant weight change. Adequate protein intake and balanced nutrition can help support hair health during weight loss.