Starting Mounjaro raises practical questions about how you might feel in the first weeks. This week by week guide explains common side effects, simple ways to reduce them, when to speak to a doctor and how to plan dose increases. Everyone is different, so use this as a supportive framework alongside your doctor’s advice.
Week 1 to 4 on low dose Mounjaro: settling in and nausea management
The first dose is usually low so you can adapt. Nausea, burping, reduced appetite, constipation or diarrhoea are common at the start. Eat slowly, keep water intake steady and choose smaller meals. Many people find soup, yoghurt, porridge, eggs, beans, fish or chicken with vegetables easier than heavy meals.
Spacing coffee, spicy foods and alcohol away from the injection day can help. If reflux or constipation appears, ask a pharmacist about suitable over the counter options. If vomiting, dehydration or severe tummy pain occurs, contact a doctor promptly.
Week 5 to 8: increasing the dose and preventing reflux
As your dose rises, reflux or a feeling of fullness can return. Keep portions small, avoid very high fat meals and try to eat earlier in the evening. Consider planning the next day’s meals so choices stay gentle while you adjust.
Bring questions to your review and share patterns you have noticed. If symptoms flare with each increase, ask whether pausing at the current dose for longer is a safer plan before moving up.
Week 9 to 12: listening to appetite and protecting hydration
Appetite usually falls further. Focus on protein, fibre and fluids rather than very low calories. Add beans, lentils, eggs, fish or chicken and plenty of vegetables. If you are losing weight quickly or feel lightheaded, raise this with your doctor.
Note any medicines that can irritate the stomach and take them with food if appropriate. If you develop persistent severe tummy pain, black stools or repeated vomiting, stop treatment and seek urgent care.
Beyond week 12: maintenance dose and long term comfort
Once you find a comfortable dose, side effects often settle. Continue gentle activity, steady sleep routines and a simple meal plan. Book regular reviews to check comfort, goals and any other medicines that might need dose changes.
If you plan to order Mounjaro online see our step by step guide to ordering with a doctor review.
Practical tips to reduce Mounjaro side effects
- Eat slowly, stop before you feel very full and avoid heavy late meals.
- Choose lean protein, whole grains, fruit and vegetables; keep water intake steady.
- Plan injection day meals to be simple and easy to digest.
- Keep a note of symptoms and bring it to reviews.
- Rest and choose light foods if you feel unwell. Seek medical advice if symptoms are severe or persistent.
When to contact a doctor during treatment
Speak to a doctor if you have severe or persistent tummy pain, repeated vomiting, signs of dehydration or black stools. Discuss planned surgery or deep sedation in advance due to delayed stomach emptying on GLP-1 treatment.
Supports available in Ireland
- HPRA, authorised medicine record: Mounjaro
- HSE, medicines for obesity
- HSE, obesity treatment overview
FAQs
How long do Mounjaro side effects last?
They usually settle within days to weeks at each dose. If symptoms remain or are severe, contact a doctor to review dose pacing or supportive treatment.
Can I drink alcohol on Mounjaro?
Alcohol can worsen nausea and reflux. If you choose to drink, keep amounts small and avoid drinking near your injection day while you adjust.
What should I eat if I feel nauseous?
Light choices such as soup, yoghurt, porridge, crackers, bananas or eggs are usually easier than fried or spicy meals.
Where can I see current prices of Mounjaro in Ireland?
Visit Mounjaro for our up to date pricing.
If you would like to check suitability, you can fill in a quick questionnaire with our online doctor partner, Zava.
Need pharmacist advice today? Ask a Pharmacist.
