As do most all medications, there are some possible side effects. Most are mild and generally improve quickly. Most are seen at higher doses until your body adjusts. carry a risk of potential side effects. Any side effects of GLP-1s are typically mild and often improve within the first few weeks of treatment. Some of these are: Fatigue, Headaches, Dizziness, Belching and gas, Acid reflux, Heartburn, Diarrhea, Stomach pains, Upset stomach, Vomiting, Nausea.