Side Effects

GLP-1 Side Effects: What to Actually Expect (and What Helps)

Most GLP-1 side effects are manageable and improve significantly after the first month.

GLP-1 medications work — but they come with a adjustment period that catches a lot of people off guard. Knowing what's normal versus what's a warning sign can make the difference between pushing through and quitting too early.

Common Side Effects (What's Normal)

The most frequently reported side effects, especially in the first 4–8 weeks:

• Nausea — the most common, affects 30–40% of users. Usually worst after injection and improves within a few hours. Tends to decrease significantly after the first month.
• Constipation or diarrhea — GLP-1 medications slow gastric emptying, which can disrupt your normal digestion pattern
• Fatigue — especially early on, as your body adjusts and you're eating significantly less
• Reduced appetite — this is the mechanism, not a side effect per se, but can feel extreme at first
• Mild headaches — often related to reduced calorie intake rather than the medication itself

How to Minimize Nausea

Most people who quit GLP-1 medications do so because of nausea in the first few weeks. These strategies make a real difference:

• Eat smaller portions — the drug slows gastric emptying; large meals exacerbate nausea significantly
• Inject at night before bed — the worst nausea hits ~4–6 hours post-injection; sleeping through it helps
• Avoid high-fat foods — fat slows digestion further; greasy food + GLP-1 is a rough combination
• Stay hydrated — nausea is worse when dehydrated
• Give it 4 weeks — the body adapts; most people report significant improvement after the first month

Side Effects That Need Medical Attention

These are not normal and require contacting your provider:

• Severe abdominal pain — especially if it radiates to the back (pancreatitis warning sign)
• Persistent vomiting — unable to keep fluids down for more than 24 hours
• Signs of allergic reaction — rash, difficulty breathing, swelling of face/lips/throat
• Vision changes — rapid changes in blood sugar can affect vision in some patients
• Gallbladder pain — rapid weight loss increases gallstone risk; right-side abdominal pain should be evaluated

The Muscle Loss Problem (and How to Avoid It)

One underreported issue with GLP-1 medications: rapid weight loss can include significant muscle mass loss — in some studies, up to 40% of weight lost was lean mass. This matters for long-term metabolic health.

How to protect muscle while on GLP-1:

• Prioritize protein — aim for 0.7–1g per pound of body weight daily
• Resistance train at least 2–3x per week
• Don't cut calories too aggressively beyond what the medication already does

This is one reason programs like Found and Calibrate that include coaching are worth considering — they actively address this with their members.

Bottom Line

Side effects are real but manageable for most people. The first 4 weeks are the hardest. If you can push through with the right strategies, the long-term results are well documented.

The best programs give you provider access when side effects hit — so you're not googling symptoms at 2am wondering if something is wrong.