Managing Common GLP-1 Side Effects: A Pharmacist's Guide
Practical, pharmacist-written ways to ease nausea, constipation and tiredness on a GLP-1 medicine like Mounjaro or Wegovy, and clear guidance on when to contact your prescriber.
Most people starting a GLP-1 medicine get some side effects in the early weeks. They are usually mild, they usually settle, and most of them respond well to a few simple habits. This guide covers the common ones and what actually helps, plus the small number of symptoms that need a prompt call to your prescriber.
Nausea
Nausea is the most common early side effect, especially in the first weeks and for a day or two after a dose increase. It happens because the medicine slows how quickly your stomach empties.
What tends to help:
- Eat smaller meals, more slowly, and stop when you feel comfortable rather than full.
- Choose plainer food while it settles. Grilled rather than fried, and lighter sauces.
- Keep fatty, greasy and very rich meals for later. They sit in the stomach longest.
- Sip fluids through the day rather than drinking a lot with meals.
- Ginger tea or ginger biscuits help some people, and a short walk after eating often settles things.
If you find a particular meal reliably triggers it, note it down. A simple food and symptom diary makes the pattern obvious within a week or two, and gives your prescriber something useful to work with. This is exactly what a food diary is for in the early weeks.
Constipation
Slower digestion plus eating less means less moving through your system, and often less fibre and fluid too. Constipation is very common and very fixable.
- Drink more water than feels natural. Reduced appetite quietly reduces fluid intake, which makes constipation worse. Our hydration guide has simple targets.
- Eat fibre deliberately: vegetables, fruit, beans, lentils, wholegrains, or a spoonful of linseed on yoghurt.
- Keep moving. Even daily walking helps your gut do its job.
- If it persists, ask your pharmacist about a gentle laxative that suits you. This is a routine conversation and nothing to put up with in silence.
Tiredness
Some tiredness in the early weeks is common. Your body is adjusting, and you are eating less than it is used to. Two things make it worse: eating too little protein and drifting into dehydration. Both are easy to correct. Aim for enough protein at each meal, keep your fluids up, and be a little patient with yourself while your body adapts.
If tiredness is severe, or it is getting worse rather than better after the first few weeks, speak to your prescriber.
Heartburn and reflux
A slower stomach can mean acid hangs around longer. Smaller meals help, as does not lying down for a couple of hours after eating. If you get regular heartburn, your pharmacist can advise on short-term options and whether anything needs a closer look.
When to contact your prescriber promptly
Most side effects are a nuisance rather than a danger. A few things are different. Contact your doctor, pharmacist or prescriber promptly, or seek urgent care, if you have:
- Severe or persistent abdominal pain, especially if it spreads to your back
- Vomiting that will not settle, or signs of dehydration such as dark urine, dizziness or confusion
- A very rapid heartbeat, chest pain or difficulty breathing
- Severe pain in the upper right of your tummy
- A spreading, hot or swollen injection-site reaction
These are uncommon, but they matter. When in doubt, always check. NHS 111 is there for exactly this.
Side effects are a phase for most people, not the price of admission forever. Handle the basics, keep notes, and let your prescriber know what you are experiencing at each review.
Sources: NHS medicines guidance and the patient information leaflets for semaglutide and tirzepatide.