Common GLP-1 side effects
Because GLP-1 slows digestion, the most common side effects affect the stomach and gut. They are usually worst when you start or increase a dose and improve over a few weeks.
- Nausea (the most common)
- Constipation or diarrhea
- Bloating, gas and burping
- Feeling full very quickly
- Mild headache
- Tiredness
- Mild injection-site redness (for injections)
Tips to reduce GLP-1 side effects
- Eat smaller meals and stop when you feel satisfied, not stuffed.
- Slow down – eat slowly and chew well.
- Limit greasy, fried and very sugary foods, which often trigger nausea.
- Drink plenty of water through the day to help constipation and headaches.
- Add fiber gradually from vegetables, fruit and whole grains.
- Don't lie down right after eating.
- Follow your dose schedule and never increase faster than prescribed.
- Message your care team if side effects don't settle – your clinician may adjust the dose.
When to contact your clinician
- Side effects that stop you eating or drinking normally
- Stronger or persistent headaches
- Signs of low blood sugar (shakiness, sweating, confusion), especially if you take other diabetes medicines
- Trouble sleeping or mood changes
- Vomiting or diarrhea lasting more than a day or two
Serious risks and warnings
Prescribing information for GLP-1 medicines lists warnings including pancreatitis, gallbladder problems, kidney problems (often linked to dehydration), serious allergic reactions and low blood sugar when combined with some diabetes medicines. Brand-name GLP-1 medicines also carry a warning about thyroid C-cell tumors seen in rodents. This is why a full health history review by a licensed clinician matters.
Who should not use GLP-1
- People who are pregnant, breastfeeding or planning pregnancy
- Anyone with a personal or family history of medullary thyroid carcinoma or MEN2
- People with a history of pancreatitis
- People with certain serious gallbladder, kidney or liver conditions (discuss with a clinician)
- Anyone under 18
This page does not list every possible side effect. Always read the information provided with your medication and ask your clinician or pharmacist about anything you're unsure of.
Frequently Asked Questions
What is the most common GLP-1 side effect?
Nausea is the most common side effect. It usually improves within a few weeks and is often worse right after a dose increase.
Do GLP-1 side effects go away?
For most people, digestive side effects ease as the body adjusts. If they don't, a clinician may slow down or adjust your dose.
Is GLP-1 safe?
Brand-name GLP-1 medicines have been studied in large clinical trials, but they can cause side effects and aren't right for everyone. A licensed clinician should review your health history before you start.