Glucagon-like peptide-1 (GLP-1) receptor agonists are medications used to manage type 2 diabetes and, in some cases, for weight loss. These drugs, including brands like Ozempic, Wegovy, and Mounjaro, work by mimicking a natural hormone that regulates blood sugar and appetite. They are administered as injections and prescribed for use alongside diet and exercise. While Wegovy and Mounjaro are approved for weight management, Ozempic is licensed for type 2 diabetes but is sometimes used off-label for weight loss. Mounjaro is distinct because it targets two hormone receptors, GLP-1 and GIP, which may contribute to greater weight loss.
Common Gastrointestinal Side Effects
The most frequently reported side effects of GLP-1 receptor agonists are gastrointestinal. These symptoms result from the medication’s primary action of slowing down gastric emptying. This digestive slowdown helps people feel fuller for longer but is also the primary reason for common side effects.
Nausea is the most common adverse effect, with some studies showing it affects up to 50% of patients, especially when first starting the medication or when the dose is increased. Vomiting often accompanies nausea. These side effects are most pronounced at the beginning of treatment and often subside over time.
Diarrhea is another commonly reported issue, which can lead to dehydration if not managed properly. Conversely, some individuals experience constipation as their digestive system adapts. Abdominal pain or discomfort can also occur, linked to the same delay in stomach emptying.
Less Common and Serious Health Risks
While gastrointestinal issues are common, there are less frequent but more serious health risks with GLP-1 agonists. Pancreatitis, an inflammation of the pancreas, has been reported in some patients. Symptoms include severe, persistent abdominal pain that may radiate to the back and require immediate medical attention, though it is not definitively known if the medications directly cause this condition.
Gallbladder problems, including gallstones and inflammation of the gallbladder (cholecystitis), are another potential risk. Rapid weight loss, a common outcome of using these drugs, can contribute to the formation of gallstones. Symptoms may include sharp pain in the upper-right abdomen, nausea, and jaundice.
Acute kidney injury is a rare but possible complication, often linked to severe dehydration from persistent vomiting and diarrhea. The FDA also includes a boxed warning on these medications for a potential risk of thyroid C-cell tumors. This warning is based on rodent studies; however, the risk in humans is considered uncertain, as humans have fewer of the corresponding receptors on their thyroid cells.
Managing and Mitigating Side Effects
Adjusting to GLP-1 medications can be made smoother with several practical strategies. Healthcare providers typically start patients on a low dose and gradually increase it over time. This titration process allows the body to adapt to the medication, which can significantly reduce the intensity of side effects like nausea.
Dietary modifications play a large part in managing symptoms. Eating smaller, more frequent meals rather than large ones can prevent the stomach from feeling overwhelmed. Avoiding high-fat, greasy, or spicy foods is often recommended, as these can irritate the digestive system and worsen nausea.
Staying well-hydrated is important, especially if experiencing vomiting or diarrhea, to prevent dehydration. Sipping water throughout the day is advised, while caffeine and alcohol should be limited as they can contribute to dehydration. If side effects are persistent or severe, it is important to contact a healthcare provider.
Body Composition and Appearance Changes
The significant and often rapid weight loss achieved with GLP-1 agonists can lead to noticeable changes in physical appearance. One widely discussed phenomenon is “Ozempic face,” which describes a gaunt or hollowed look in the face. This occurs due to the rapid loss of subcutaneous fat that provides volume and support to the facial skin, leading to more pronounced lines and sagging.
Beyond fat loss, a portion of the weight reduction can come from lean muscle mass. Some analyses suggest that up to 40% of the weight lost while using these medications could be from muscle if preventive measures are not taken. This loss of muscle can impact body contour, strength, and metabolism, and can further contribute to the appearance of sagging skin.
These aesthetic changes are not caused by the drug itself but are consequences of the rapid weight reduction it facilitates. Maintaining adequate protein intake and incorporating resistance exercise can help preserve muscle mass during treatment, potentially mitigating some of these effects.