If you’re reading this, chances are you’re either thinking about starting Mounjaro or you’ve already got that little injection pen in your fridge and you’re preparing for what comes next. First off—welcome. Whether you’re here for weight management or to better control type 2 diabetes, you’ve made a decision that could genuinely change your life. But let’s be real. It’s not always smooth sailing. One of the biggest reasons people give up on Mounjaro isn’t because it doesn’t work—it’s because the side effects can catch you off guard. I’ve been on the same rollercoaster, and while I’m not a doctor or scientist, I’ve learned a lot from trial, error, and listening to others who are also on this journey. This post is simply about sharing what I’ve learned, in the hope it might help you manage your side effects better—and stick with a treatment that, for many of us, is proving to be life-changing.
Let’s start by looking at the most common side effects people report when taking Mounjaro. According to the official patient information leaflet from the NHS, typical side effects include nausea, diarrhoea, constipation, reduced appetite, indigestion, and fatigue. Less common but still reported by many users online include burping (a lot), feeling bloated, headaches, and a sort of “Mounjaro fog”—where concentration and mental clarity seem a bit off, especially in the first few days after an injection.
I remember wondering if some of what I felt was just in my head, but when you dig into the clinical trials published in The Lancet or real-world user forums like Reddit’s Mounjaro community, you quickly realise—nope, it’s not just you. The good news? Most of these side effects ease off as your body adjusts to the medication, especially if you increase doses slowly and follow some simple strategies to help manage the symptoms.
Let’s break them down and look at what might actually help.
- Nausea and Reduced Appetite
This is probably the most talked-about effect of Mounjaro. For some, it’s mild and manageable. For others, it’s enough to ruin a whole day. Personally, this hit me hardest after moving to a higher dose. Based on my experience and what I’ve heard from other users, here’s what can help:
- Stick to small meals and eat slowly. Really slowly. Mounjaro slows digestion, so large meals can feel like a brick in your stomach.
- Avoid high-fat or greasy foods. These seem to trigger nausea more than carbs or protein.
- Ginger tea, peppermint oil, or even travel sickness bands can provide some relief.
Some people swear by anti-nausea medications, but that’s something you’d need to discuss with your GP. What helped me most was adjusting the timing of my injection. Some find doing it at night means they sleep through the worst of the nausea. For others, a morning jab works better so they can manage symptoms during the day.
- Constipation and Diarrhoea
Yes, frustratingly, you might get both—just not at the same time. Mounjaro can mess with your digestive rhythm. One week you’re bloated and sluggish, the next you’re rushing to the loo after a meal you used to digest fine.
To manage constipation:
- Drink lots of water. This one sounds obvious, but when you’re not eating much, it’s easy to forget to stay hydrated. Aim for at least 2–3 litres a day.
- A fibre supplement like psyllium husk can gently help. I use one that dissolves into water without any flavour—makes it easier to get down.
- Gentle movement after eating, even just a walk around the block, can get things going.
For diarrhoea, again hydration is key. Some people recommend the BRAT diet (bananas, rice, applesauce, toast) when things are unsettled. Personally, I just cut back to very simple foods like plain chicken, rice, or crackers for a day or two.
- Burping, Bloating and Indigestion
This one caught me off guard. I wasn’t expecting to feel like I had a balloon in my gut after a salad. But again, it’s surprisingly common, especially in the early stages. I found that fizzy drinks, chewing gum, and eating too quickly made it worse. Switching to herbal teas instead of anything carbonated and spacing meals apart helped a lot. Some users also find relief from over-the-counter indigestion remedies like Gaviscon or Rennie, but it’s worth checking these are safe to take alongside your other medications. - Fatigue and Brain Fog
This is harder to measure but no less frustrating. On days when your energy dips, it can feel like your brain is stuck in first gear. I found this was more common on injection days or when I hadn’t eaten enough. I started keeping track of how I felt in a simple notes app, and patterns started to emerge. Eating a small, balanced meal around the same time each day helped. A short nap, or just resting with your eyes closed, was sometimes all I needed to reset.
If you’re working, I’d say avoid scheduling anything too demanding on your jab day—especially for the first few weeks. Your body is adjusting to a medication that’s changing how you process food, energy, and insulin. Give yourself a bit of grace.
- Emotional Wobbles
Here’s something that’s not talked about enough. Changing your body’s chemistry can affect your mood. Some people feel anxious, weepy, or just a bit “off.” If that’s you, you’re not alone. The sudden appetite suppression can also trigger emotional eating patterns or make you confront your relationship with food in a new way. Journaling helped me work through some of those feelings. So did chatting with others going through the same thing, either in online groups or by reading stories from fellow users.
Top Tips for Managing Mounjaro Side Effects
- Start low, go slow. If you’re increasing your dose, give your body a couple of weeks to adjust before moving up again.
- Keep a symptom tracker. It helps you spot patterns and gives you useful info to share with your GP if needed.
- Eat simply and avoid trigger foods, especially during the first few days after an injection.
- Don’t suffer in silence. There are loads of supportive communities out there, like the Mounjaro UK Facebook group or dedicated Reddit threads.
- Rest when you need to. Your body is doing something big – give it the support it needs.
Of course, everyone’s different. What works for one person might not work for the next. And as always, anything new or worrying should be discussed with your doctor or diabetes nurse. This post isn’t medical advice, just shared experience from someone in the same boat.
To wrap up – Mounjaro can be a brilliant tool, but it’s not without its bumps in the road. I know many people who’ve nearly given up on it because of the side effects, only to find that with a few tweaks and a bit of patience, those same issues eased up. If you’re struggling now, just know that it does get easier. You’re not doing it wrong. Your body’s just adjusting. And you’re not alone.
