GLP‑1 Side Effects Survival Guide (Wegovy, Mounjaro, Ozempic): What Helps, What Usually Settles, and When to Call Your Clinic

Starting (or increasing) a GLP-1 medication can feel like your body is “learning a new normal.” Most side effects are digestive, often strongest in the first 1–4 weeks of a new dose, and usually improve as your system adapts. This guide is a practical, UK-friendly checklist to help you stay safe and more comfortable.

The most common side effects (and why they happen)

GLP-1s slow stomach emptying and reduce appetite signals. That can trigger:

• Nausea / queasiness

• Reflux / heartburn

• Constipation or diarrhoea

• Bloating / “full quickly”

• Fatigue / headaches (often linked to lower intake, dehydration, or low electrolytes)

What helps first (simple, evidence-aligned habits)

1) Nausea

• Eat smaller meals, more often; avoid huge portions.

• Choose bland, low-fat foods when symptoms flare (toast, bananas, rice, soup).

• Sip fluids steadily; try ginger or peppermint tea if it suits you.

• Don’t lie down right after eating.

2) Reflux / heartburn

• Keep evening meals lighter; avoid late-night heavy/spicy/fatty foods.

• Stay upright for 2–3 hours after meals.

• If you use an OTC remedy, follow the label and check with a pharmacist, especially if you’re on other medications.

3) Constipation

• Prioritise fluid + fibre + movement (in that order).

• Add fibre gradually (too fast can worsen bloating).

• Aim for a short daily walk; gentle activity helps gut motility.

4) Diarrhoea

• Focus on hydration: water, clear soups, oral rehydration if needed.

• Temporarily reduce very fatty foods and large portions.

• If diarrhoea is persistent or severe, contact your prescriber.

5) Fatigue / headaches

• A common reason is not eating enough (especially protein) and not drinking enough.

• Try “protein-first” mini-meals (yoghurt, eggs, tofu, lean meats, lentils).

• Consider electrolytes if you’ve had vomiting/diarrhoea (check suitability with a pharmacist).

What NOT to do (common mistakes)

• Don’t double-dose to “catch up.”

• Don’t push through severe symptoms without advice.

• Don’t dramatically increase fibre overnight (hello, bloat).

• Avoid alcohol when symptoms are active, it can worsen nausea and dehydration.

When to contact your clinic urgently

Seek same-day medical advice if you have:

• Severe, persistent abdominal pain (especially if it spreads to the back)

• Repeated vomiting, inability to keep fluids down, or signs of dehydration (dizziness, very dark urine)

• Blood in vomit or stool, black stools, or severe ongoing diarrhoea

• Allergic reaction symptoms (swelling, breathing difficulty)

Mini FAQ

1.      How long do side effects last?
Often a few days to a couple of weeks after starting or increasing a dose.

2.      Should I move up a dose if I feel awful?
Not without clinician guidance, many people benefit from staying longer on a dose.

3.      What’s the #1 survival habit?
Hydration + small meals + slow eating.