5-10% of those taking GLP-1 agonists discontinue treatment citing nausea, diarrhea, indigestion, vomiting, and abdominal pain. Patients often must change not just how much they eat but what they eat, especially, reducing fat intake, eating smaller meals, and staying active right after eating.

"What are the gastrointestinal adverse effects of the glucagon-like peptide 1 receptor agonists, and how should they be managed?"

https://illinoisadvance.com/what-are-gastrointestinal-advers...

"Risk of Gastrointestinal Adverse Events Associated With Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss"

https://jamanetwork.com/journals/jama/fullarticle/2810542

The main bad side effect is that you need to be really conscious about food. It’s easy to eat not enough or not to eat at all. Then unavoidably you feel really weak and metabolism slows down. You need to be really conscious to eat enough healthy foods, especially if you want to exercise.

They're modified hormones. Normal glutide made by the body has a 5 minute half life and makes you feel full. Semaglutide has a 1 week half life.

If you’ve ever had pancreatitis you can’t take this (me) because it increases overall risk of having an episode. If you’re unlucky like me and have a predisposition for pancreatitis or gallbladder issues, this can push you over the edge into the worst pain of your life and possible life threatening complications. But the percentage of folks at risk is relatively low so this is not a concern for most. Heavy alcohol consumption is a leading cause of pancreatitis so for folks with AUD and diabetes, if this cuts down both diabetes and the causal factor (drinking), maybe it’s a net positive if they’ve never had pancreatitis before. Unfortunately severe pancreatitis increases the risk of Type 2 and 3 diabetes and unfortunately this great treatment won’t be available.

I had to stop taking it because it increased my resting heart rate by about 25 bpm.

Basically a magic pill (well, injection). Some mild nausea and indigestion at first, but nothing ginger tea and some over-the-counter antacids couldn't handle. Some people get severe nausea, and have to stop taking them. Only real issue at the moment is the high cost: $1k/month in the US, $500 rest-of-the-world, or cheaper in countries that subsidise them.