Why GLP-1 Drugs Cause Certain Side Effects
Common side effects of GLP-1s include nausea, vomiting, and diarrhea. These are due to the delayed gastric emptying, the same mechanisms that make them effective for weight loss and blood sugar control, Duah says.
“These medications also interact with areas of the brain involved in appetite regulation and nausea,” Duah says. “In some people, that signaling can temporarily trigger nausea, particularly during the first few weeks of treatment.” Diarrhea and constipation can also happen because GLP-1 can affect bowel movements, she adds.
“Side effects are most common during the first several weeks of treatment and after dose increases, and they often improve as the body adapts,” Duah says. That’s why the drugs are typically started at a low dose and increased over several months, Kothari says.
Side effects tend to be the same whether you’re taking an oral or injectable form of GLP-1s, Kothari says.
