What to expect
Most side effects from GLP-1 medications affect the stomach and gut. They're usually mild to moderate, show up most often when you start or increase a dose, and ease as your body adjusts over a few days to weeks. That's why doses start low and go up slowly.
Common side effects and what helps
Eat smaller meals, stop at the first sign of fullness, and eat slowly. Bland foods like crackers, rice, and toast help. Skip greasy, fried, and very sweet foods.
Drink plenty of water, add fiber slowly (vegetables, fruit, whole grains), and stay active. Ask your provider before using a laxative.
Sip fluids through the day, including drinks with electrolytes. Avoid high-fat foods and sugar alcohols.
Pause food for a few hours, then sip clear fluids. If you can't keep fluids down for a day, contact your provider.
Eat smaller portions, avoid lying down for 2 to 3 hours after eating, and limit spicy food, carbonation, and alcohol.
Often from eating less. Eat enough protein, stay hydrated, and keep a regular sleep schedule.
Usually linked to dehydration or eating very little. Drink water and don't skip meals entirely.
Mild redness, itching, or a small bump can happen. Rotate sites and let alcohol dry before injecting.
Habits that make a difference
- Protein first. Aim for protein at every meal to help protect muscle while you lose weight.
- Strength training. Two or three sessions a week helps you keep muscle.
- Hydrate. Eating less food means taking in less water. Keep a bottle with you.
- Go easy on alcohol. It can worsen nausea and low blood sugar.
- Don't rush dose increases. If side effects are hard to manage, your prescriber can hold your dose a little longer.
Some people notice hair thinning a few months into rapid weight loss. It's usually temporary and tied to the weight loss itself.
When to get medical help
Swelling of the face, lips, tongue, or throat, trouble breathing, or a severe rash (signs of an allergic reaction).
Contact your provider right away if you have:
- Severe stomach pain that won't go away, with or without vomiting, sometimes spreading to your back. This can be a sign of pancreatitis.
- Pain in the upper right belly, fever, yellowing of the skin or eyes, or clay-colored stools. These can be gallbladder problems.
- Signs of dehydration: very little urine, dark urine, dizziness when standing, or being unable to keep fluids down.
- Low blood sugar if you also take insulin or a sulfonylurea: shakiness, sweating, confusion, or a fast heartbeat.
- A lump or swelling in your neck, hoarseness, or trouble swallowing.
- Changes in your vision if you have diabetes.
- New or worsening depression, or thoughts of harming yourself.
Peptide side effects
Side effects vary by peptide, and many have limited human research. Commonly reported effects include:
- Any injected peptide: redness, itching, or a small bump at the injection site.
- Growth-hormone-releasing peptides (Sermorelin, Ipamorelin / CJC-1295, Tesamorelin): flushing, headache, increased hunger, mild water retention, or tingling in the hands.
- PT-141: nausea (common, especially with the first doses), flushing, headache, and a brief rise in blood pressure. Use no more than once in 24 hours.
- NAD+: a warm or flushed feeling, nausea, or discomfort at the injection site.
Tell your provider about any side effect that's bothersome or doesn't go away.

