Mounjaro (tirzepatide) is a dual GIP/GLP-1 receptor agonist licensed in the UK for type 2 diabetes management, whilst corticosteroid injections are widely used to treat joint inflammation and musculoskeletal conditions. Patients taking Mounjaro may require steroid injections for conditions such as arthritis or tendonitis, raising important questions about safety and blood glucose management. Although there is no absolute contraindication to receiving a cortisone shot whilst taking Mounjaro, the combination requires careful consideration due to opposing effects on glycaemic control. This article examines the clinical considerations, monitoring requirements, and practical guidance for UK patients managing both treatments concurrently.

Understanding Mounjaro (Tirzepatide) and Steroid Injections

Mounjaro (tirzepatide) is a prescription medicine licensed in the UK for the treatment of type 2 diabetes mellitus. It belongs to a class of medications known as dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonists. Tirzepatide works by mimicking the action of incretin hormones, which stimulate insulin secretion in response to food intake, suppress glucagon release, slow gastric emptying, and reduce appetite. This dual mechanism helps improve glycaemic control and promotes weight loss. For weight management, tirzepatide is marketed in the UK under the brand name Zepbound.

Administered as a once-weekly subcutaneous injection, Mounjaro is typically started at a low dose (2.5 mg) and gradually increased to minimise gastrointestinal side effects such as nausea, vomiting, and diarrhoea. Common adverse effects also include decreased appetite, constipation, and injection site reactions. Patients taking Mounjaro should be aware of potential risks including pancreatitis, gallbladder problems (cholelithiasis/cholecystitis), and diabetic retinopathy complications (particularly in those with pre-existing retinopathy when glycaemic control improves rapidly). The risk of hypoglycaemia increases when Mounjaro is used with insulin or sulfonylureas, and doses of these medications may need to be reduced.

Steroid injections, also known as corticosteroid injections, are anti-inflammatory treatments commonly used to manage joint pain, inflammation, and certain musculoskeletal conditions such as arthritis, bursitis, tendonitis, and frozen shoulder. These injections deliver a synthetic corticosteroid (such as methylprednisolone or triamcinolone) directly into the affected joint or soft tissue, providing localised relief by reducing inflammation and suppressing the immune response. Steroid injections are widely used in UK clinical practice and are often administered by GPs, rheumatologists, or orthopaedic specialists. While generally safe, corticosteroid injections can have systemic effects, particularly on glucose metabolism, which is an important consideration for individuals with diabetes or those taking glucose-lowering medications like Mounjaro.

Can You Have a Steroid Injection While Taking Mounjaro?

There is no absolute contraindication to receiving a steroid injection while taking Mounjaro. The MHRA-approved Summary of Product Characteristics (SmPC) for tirzepatide does not explicitly prohibit the concurrent use of corticosteroid injections with GLP-1 receptor agonists, and current NICE guidance does not specifically restrict this combination. However, this does not mean the combination is without considerations. Healthcare professionals must evaluate each patient individually, taking into account their diabetes control, overall health status, and the clinical indication for the steroid injection.

The primary concern when combining these treatments relates to the opposing effects on blood glucose levels. While Mounjaro works to lower blood sugar and improve glycaemic control, corticosteroids—even when administered locally—can raise blood glucose levels by increasing insulin resistance and promoting hepatic glucose production. This counteractive effect may temporarily reduce the effectiveness of Mounjaro in controlling blood sugar, particularly in the days following the injection.

It is essential to inform your prescribing clinician or diabetes specialist if you are taking Mounjaro before receiving a steroid injection. Your healthcare provider can assess whether the benefits of the corticosteroid injection outweigh the potential risks and can provide guidance on monitoring your blood glucose more closely during the period following the injection. In most cases, the metabolic impact of a single steroid injection is transient and manageable with appropriate monitoring and, if necessary, temporary adjustments to diabetes management. If your blood glucose levels repeatedly exceed 15 mmol/L despite your usual measures, contact your diabetes team promptly. Patients should never decline medically necessary treatment due to concerns about drug interactions without first discussing these concerns with a qualified healthcare professional.

How Steroid Injections May Affect Blood Sugar Control

Corticosteroids, including those administered via injection, are known to cause hyperglycaemia (elevated blood glucose levels). This effect occurs through several mechanisms. Corticosteroids increase hepatic gluconeogenesis (the production of glucose by the liver), reduce peripheral glucose uptake by tissues, and promote insulin resistance, making the body's cells less responsive to insulin. Even localised injections can have systemic effects, as some of the corticosteroid is absorbed into the bloodstream.

The magnitude and duration of blood glucose elevation following a steroid injection vary depending on several factors:

• Type and dose of corticosteroid: Longer-acting preparations and higher doses are more likely to cause significant hyperglycaemia.

• Site of injection: Intra-articular (into the joint) injections may have less systemic absorption than intramuscular injections, though both can affect blood sugar.

• Individual patient factors: People with diabetes or prediabetes are more susceptible to corticosteroid-induced hyperglycaemia. Baseline glycaemic control, body weight, and insulin sensitivity all influence the response.

• Duration of effect: Blood glucose elevation typically peaks within 24-72 hours after injection and usually lasts for a few days, occasionally persisting for up to 1-2 weeks depending on the steroid preparation used.

For patients taking Mounjaro, this temporary rise in blood glucose may partially counteract the glucose-lowering effects of tirzepatide. While Mounjaro continues to work through its incretin-based mechanisms, the corticosteroid-induced insulin resistance may result in higher-than-usual blood glucose readings during the post-injection period. This does not mean Mounjaro has stopped working, but rather that the metabolic challenge posed by the corticosteroid requires additional vigilance and possibly temporary adjustments to diabetes management. Most patients will see their blood glucose levels return to baseline once the corticosteroid effect wanes.

Precautions and Monitoring When Combining These Treatments

If you require a steroid injection while taking Mounjaro, enhanced blood glucose monitoring is strongly recommended. Patients with type 2 diabetes should check their blood glucose levels more frequently than usual—ideally several times daily—for at least 1–2 weeks following the injection. This allows early detection of hyperglycaemia and enables timely intervention if blood sugar levels rise significantly.

Key precautions include:

• Pre-injection discussion: Inform the healthcare professional administering the steroid injection that you are taking Mounjaro. They may choose a lower dose or shorter-acting corticosteroid if clinically appropriate.

• Diabetes team consultation: Contact your GP, diabetes nurse, or endocrinologist before or shortly after receiving the injection. They can provide personalised advice on monitoring and may recommend temporary adjustments to your diabetes management plan.

• Blood ketone testing: Check blood ketones if your glucose level exceeds 15 mmol/L or if you feel unwell, especially if you are also taking an SGLT2 inhibitor. Seek urgent medical help if ketones are elevated.

• Dietary vigilance: Maintain a consistent, balanced diet and avoid excessive carbohydrate intake during the period of potential hyperglycaemia.

• Hydration: Drink plenty of water, as elevated blood glucose can increase urination and risk of dehydration.

• Medication adherence: Continue taking Mounjaro as prescribed unless specifically advised otherwise by your healthcare provider. Do not stop or adjust your dose without medical guidance. If pancreatitis is suspected, discontinue Mounjaro immediately and seek urgent medical assessment.

• Additional medication: In some cases, your diabetes team may temporarily adjust insulin doses or consider short-term sulfonylurea therapy (e.g., gliclazide) to manage steroid-induced hyperglycaemia. Initiating SGLT2 inhibitors during periods of steroid use is generally not recommended due to the increased risk of euglycaemic diabetic ketoacidosis.

NICE guidance on diabetes management emphasises individualised care and regular monitoring, particularly when factors that may affect glycaemic control are introduced. While there is no specific NICE guidance on the combination of tirzepatide and steroid injections, the principles of careful monitoring and patient-centred decision-making apply. Contact your diabetes team if your blood glucose levels persistently exceed 15 mmol/L despite your usual management strategies. Patients should feel empowered to ask questions and seek clarification from their healthcare team about any concerns regarding their treatment plan.

When to Seek Medical Advice

Prompt medical advice should be sought if you experience any concerning symptoms after receiving a steroid injection while taking Mounjaro. While most patients tolerate the combination well with appropriate monitoring, certain warning signs require urgent attention.

Contact your GP or diabetes team if you notice:

• Persistently elevated blood glucose levels: Readings consistently above 15 mmol/L despite usual management.

• Symptoms of hyperglycaemia: Increased thirst, frequent urination, unusual fatigue, blurred vision, or unexplained weight loss.

• Elevated ketones: If blood ketones are present when testing (particularly if glucose is >15 mmol/L or you feel unwell). This is especially important if you are also taking an SGLT2 inhibitor.

• Signs of diabetic ketoacidosis (DKA): Although rare with type 2 diabetes, seek immediate medical attention if you experience nausea, vomiting, abdominal pain, rapid breathing, fruity-smelling breath, or confusion.

• Severe gastrointestinal symptoms: Worsening nausea, vomiting, or diarrhoea, particularly if these prevent adequate food or fluid intake, as dehydration can complicate blood glucose management.

• Injection site problems: Unusual pain, swelling, redness, or signs of infection at either the Mounjaro or steroid injection site.

• Symptoms of pancreatitis: Severe, persistent abdominal pain (often radiating to the back), nausea, and vomiting. This is a rare but serious side effect of GLP-1 receptor agonists that requires immediate medical assessment. Stop taking Mounjaro if pancreatitis is suspected and seek urgent medical care. Only restart if pancreatitis has been ruled out.

Seek emergency care (call 999 or attend A&E) if you experience:

• Severe symptoms of hyperglycaemia with altered consciousness or inability to manage symptoms at home.

• Signs of severe allergic reaction (anaphylaxis) to either medication, including difficulty breathing, facial swelling, or widespread rash.

Routine follow-up with your diabetes team is advisable within 2–4 weeks of receiving a steroid injection to review your blood glucose patterns and ensure your diabetes management remains optimised. Open communication with your healthcare providers is essential for safe, effective treatment and helps ensure that both your musculoskeletal condition and diabetes are managed appropriately.

If you suspect you have experienced a side effect from Mounjaro or a steroid injection, you can report this through the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk).

Frequently Asked Questions