Mounjaro Weight Loss Injection

Mounjaro® is primarily used in the NHS to manage type 2 diabetes and to aid weight loss in individuals with obesity or overweight with certain conditions.

Clinical trials have shown weight loss of up to 20% of body weight in some patients, depending on dosage and lifestyle factors.

Yes, Mounjaro® is a prescription-only medication. The supply of Mounjaro is only made if it is safe and appropriate, following assessment by one of our clinical team.

is a once-weekly injection that is injected under the skin (subcutaneous injection) of your stomach area (abdomen) or upper leg (thigh) or upper arm. Further information can be found in the patient information leaflet and video link.

Storing Your Mounjaro Pens 

• Before Use: Keep your pens in the refrigerator to maintain their effectiveness. 
• After Opening: Once opened, you can store the pen at room temperature for up to 30 days.  

 With your first order, you will receive a sharps bin, a special waste bin for storing sharps materials like needles until they can be safely disposed of. After each use, place the needle into the sharps bin. Once you have used all 4 doses and removed the needle, you can dispose of the pen in your household waste or the sharps bin. When the sharps bin is full, your local council can collect it for disposal. After starting treatment, you can purchase additional sharps bins with new orders. 

Each person responds differently to Mounjaro. Your Mounjaro treatment starts with a low dose and increases gradually. This helps your body adjust and minimizes potential side effects. The prescriber may increase the dose by 2.5mg increments every four weeks if well tolerated. A typical schedule may look like this: 

• Weeks 1–4: Start with 2.5 mg 
• Weeks 5–8: Increase to 5 mg (stay on this dose if it’s working well for you) 
• Weeks 9–12: Move up to 7.5 mg 
• Weeks 13–16: Increase to 10 mg (if still effective, you can stay here) 
• Weeks 17–20: Step up to 12.5 mg 
• Weeks 21+: Finally, move to 15 mg (remain on this dose if tolerated and effective) 

Do not change your dose unless your prescribing healthcare professional has told you to. 

Tip: If you notice any persistent side effects when increasing your dose, contact the Happy Pharmacy team for advice—we’re here to guide you

Like all medicines, this medicine can cause side effects, although not everybody gets them. Serious side effects are rare.

These include:

Uncommon
(may affect up to 1 in 100 people) - Inflamed pancreas (acute pancreatitis) which could cause severe pain in the stomach and back which does not go away.
You should see a doctor immediately if you experience such symptoms.

Rare
(may affect up to 1 in 1 000 people) - Severe allergic reactions (e.g. anaphylactic reaction, angioedema). You should get immediate medical help and inform your doctor if you experience symptoms such as breathing problems, rapid swelling of the lips, tongue and/or throat with difficulty swallowing and a fast heartbeat.

Like all medications, Mounjaro, Wegovy, and Saxenda can cause some side effects. Generally, these side effects are mild and are likely to diminish or even disappear after a few weeks of treatment. 

We understand how challenging it can be to cope with these discomforts as your body adjusts to the medication. That’s why we’ve compiled our top tips for managing these potential side effects to help ease any discomfort you may experience. If you need any further assistance please do not hesitate to contact the Clinical Team at Happy Pharmacy.  

The most common side effects include:

- Nausea and/or vomiting 

- Constipation 

- Headache 

- Heartburn 

- Diarrhoea

- Injection site reactions 

- Gallstones and inflammation of the gallbladder 

Nausea and/or vomiting 

Frequency: These side effects are very common (may affect more than 1 in 10 people) and are usually not severe. They are most common when first starting the treatment but decrease over time in most patients.  

Management Tips: 

Stay well-hydrated; aim for at least 8 cups of water daily. 

Eat small, regular meals to avoid an empty stomach. 

Try soothing beverages such as ginger, peppermint, or fennel teas. 

Take anti-sickness medications such as Cyclizine to help manage symptoms of nausea and vomiting as your body adjusts to the treatment. 

Visit the NHS website linked below for more information on dealing with nausea and vomiting.  

 When to Seek Assistance: If vomiting occurs more than three times a day or if you experience symptoms of dehydration (dark urine, dizziness), stop the treatment and consult NHS 111. 

Constipation 

Frequency: This side effect is very common (may affect more than 1 in 10 people) and is usually not severe. It is most common when first starting the treatment but decreases over time in most patients.  

 Management Tips: 

Stay well-hydrated; aim for at least 8 cups of water daily. 

Eat high-fiber foods such as prunes, figs and oats in your diet.  

Consider increasing your activity as this can stimulate bowel movements. 

Try a mild laxative.  

Visit the NHS website linked here for more information on dealing with constipation.  

When to Seek Assistance:  If you’ve tried the management tips above but are still constipated or notice blood in your stool, consult your GP or NHS 111 for advice. 

 

Headache 

Frequency: This side effect is very common (may affect more than 1 in 10 people) and is usually not severe.  

Management Tips: 

Stay well-hydrated; aim for at least 8 cups of water daily. 

Try to rest and relax. 

Take a simple painkiller like paracetamol.  

Visit the NHS website linked here for more information on managing headaches. 

When to Seek Assistance: If you’ve tried the management tips above but your headaches persist or worsen consult your GP or NHS 111 for advice. 

Heartburn

Frequency: This side effect is very common and often accompanied by nausea. 

Management Tips: 

Stay well-hydrated; aim for at least 8 cups of water daily. 

Eat small, regular meals can help. 

Avoid high-fat food that triggers your heartburn or makes it worse. 

Take a simple acid reflux medication such as Gaviscon or your pharmacist may recommend a proton pump inhibitor (PPI) that reduces how much acid your stomach makes such as Omeprazole or Lansoprazole.  

Visit the NHS website linked here for more information on managing heartburn. 

When to Seek Assistance: If you’ve tried the management tips above but your heartburn persists or worsens, you have difficulty swallowing, are vomiting blood, or feel unwell, contact your GP or NHS 111 for advice.

Diarrhoea 

Frequency: This side effect is very common (may affect more than 1 in 10 people) and is usually not severe. It is most common when first starting the treatment but decreases over time in most patients.  

Management Tips: 

Drink plenty of clear fluids, such as water or diluted squash. 

Rest and eat small meals.  

Consider oral rehydration salts, which can be obtained from your pharmacy. 

Visit the NHS website linked here for more information on managing diarrhoea. 

When to Seek Assistance: Persistent diarrhoea, the presence of blood, or an inability to stay hydrated warrants immediate contact with NHS 111. 

Injection Site Reactions 

Frequency: This side effect is common and may affect up to 1 in 10 people and often resolves as your body adjusts to the treatment.  

 

Symptoms: Redness, bruising, itching, swelling, or pain. 

Management Tips: Use a non drowsy antihistamine cream or take an antihistamine tablet.  

When to Seek Assistance: If the reaction worsens, spreads, or becomes unbearable, discontinue the medication and consult your GP or NHS 111. 

Gallstones and Gallbladder Inflammation 

Frequency: Affects up to 1 in 10 users of Wegovy and Saxenda; up to 1 in 100 users of Mounjaro. 

Management Tips: 

Avoid rapid weight loss by maintaining a steady pace (no more than 1.5 kg or 3 lbs per week). 

Stay hydrated and eat smaller, frequent meals. 

When to Seek Assistance: Severe pain under the ribs, vomiting, fever, or other signs of gallbladder issues require immediate attention. Contact NHS 111 or visit A&E. 

Adjusting Dosages to Minimise Side Effects 

Mild Side Effects: Remain on your current dose for another week before increasing. 

Moderate Side Effects: Reduce your dose for up to a week, then increase it gradually. 

Severe Side Effects: Stop the medication immediately and seek medical advice. 

Rare but Serious Side Effects 

Pancreatitis: Symptoms include severe abdominal pain radiating to the back, nausea, or vomiting. Seek urgent medical attention via NHS 111 or A&E. 

Anaphylaxis: Difficulty breathing, facial swelling, or severe allergic reactions necessitate calling 999 immediately. 

Dehydration: Symptoms include urine being dark in colour, you can’t keep fluids down, you are passing urine less often than usual, or you are feeling light-headed. Drink more fluids and seek medical attention via NHS 111 or A&E. 

Additional Information 

Our pharmacy team is available to assist with any concerns or side effects. Additionally, you can report side effects via the Yellow Card Scheme or consult your healthcare provider for advice. 

The Happy Pharmacy Team are at hand to provide accurate support and advice as needed throughout your weight loss journey. 

For further inquiries, please do not hesitate to contact us at info@happypharmacy.co.uk