Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist prescribed for type 2 diabetes and weight management in the UK. Whilst mounjaro sexual side effects are not commonly listed in official prescribing information, patients sometimes report changes in sexual function during treatment. These changes may relate to rapid weight loss, gastrointestinal symptoms, metabolic adjustments, or the underlying condition itself rather than direct drug effects. Understanding the potential mechanisms and knowing when to seek medical advice can help you manage your sexual health whilst benefiting from Mounjaro's metabolic effects.

What Is Mounjaro and How Does It Work?

Mounjaro (tirzepatide) is a prescription medicine authorised in the UK for the treatment of type 2 diabetes and for weight management in adults with obesity (BMI ≥30 kg/m²) or overweight (BMI ≥27 kg/m²) with at least one weight-related comorbidity. It belongs to a class of medications known as dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonists.

The drug works by mimicking two naturally occurring incretin hormones that play crucial roles in glucose regulation and appetite control. By activating both GIP and GLP-1 receptors, Mounjaro enhances insulin secretion when blood glucose levels are elevated, suppresses glucagon release (which reduces glucose production by the liver), and slows gastric emptying. These combined actions help improve glycaemic control in people with type 2 diabetes.

Additionally, tirzepatide acts on areas of the brain involved in appetite regulation, leading to reduced food intake and weight loss. Clinical trials have shown reductions in HbA1c levels and body weight. For weight management, Mounjaro should be used as an adjunct to a reduced-calorie diet and increased physical activity.

Mounjaro is administered as a once-weekly subcutaneous injection, typically starting at a low dose (2.5 mg) and gradually increasing over several weeks to minimise gastrointestinal side effects. The maintenance dose varies depending on individual response and tolerability, with maximum doses reaching 15 mg weekly.

Importantly, Mounjaro is not indicated for type 1 diabetes or diabetic ketoacidosis. When used with insulin or sulfonylureas, dose reductions of these medications may be needed to reduce the risk of hypoglycaemia. As with all prescription medications, Mounjaro should only be used under the supervision of a healthcare professional, and patients should be monitored regularly.

Why Might Mounjaro Affect Sexual Function?

Sexual side effects are not listed as common adverse reactions in the official prescribing information for Mounjaro, and there is no established direct pharmacological link between tirzepatide and sexual dysfunction. However, patients and healthcare professionals have raised questions about potential impacts on sexual health, and it is important to understand the possible indirect mechanisms.

Weight loss and metabolic changes associated with Mounjaro may influence sexual function in complex ways. Significant weight reduction can improve cardiovascular health, insulin sensitivity, and self-esteem—all factors that may enhance sexual wellbeing. Some patients may experience fatigue or reduced energy levels during periods of caloric restriction or rapid weight loss, which could temporarily affect interest in sexual activity, though evidence for direct hormonal effects on libido is limited.

Gastrointestinal side effects—including nausea, vomiting, diarrhoea, and abdominal discomfort—are among the most frequently reported adverse reactions with GLP-1 receptor agonists. These symptoms, particularly if persistent or severe, can understandably reduce interest in sexual activity and impact overall quality of life. Additionally, dehydration resulting from gastrointestinal upset may contribute to fatigue and reduced physical wellbeing.

It is also worth noting that type 2 diabetes itself is strongly associated with sexual dysfunction in both men and women. Erectile dysfunction, reduced libido, and difficulties with arousal or orgasm are common in people with poorly controlled diabetes due to vascular damage, neuropathy, and hormonal imbalances. Therefore, any changes in sexual function during Mounjaro treatment may reflect the underlying condition rather than the medication itself. Improved glycaemic control and weight loss may, in fact, lead to improvements in sexual health over time for many patients.

Important note for women of childbearing potential: Tirzepatide can reduce the exposure to oral contraceptives, particularly during initiation and after dose increases. Consider using a non-oral contraceptive method or additional barrier contraception for 4 weeks after starting Mounjaro and after each dose increase.

Managing Sexual Health While Taking Mounjaro

If you experience changes in sexual function while taking Mounjaro, there are several practical steps you can take to support your sexual health and overall wellbeing.

Optimise your general health: Maintaining good glycaemic control, staying well-hydrated, and ensuring adequate nutrition are fundamental. If gastrointestinal side effects are troublesome, discuss dose titration or symptomatic management strategies with your healthcare team. Eating smaller, more frequent meals and avoiding high-fat foods may help reduce nausea and improve energy levels.

Address lifestyle factors: Regular physical activity, adequate sleep, stress management, and avoiding excessive alcohol can all positively influence sexual function. Weight loss achieved through Mounjaro may improve cardiovascular fitness and self-confidence, which can enhance sexual wellbeing over time.

Consider the role of diabetes management: Improved blood glucose control often leads to better vascular and nerve function, which are critical for sexual health. If you have been experiencing sexual difficulties related to diabetes, continuing with Mounjaro and achieving better metabolic control may ultimately improve these symptoms.

Communicate openly with your partner: Sexual health is an important aspect of quality of life and relationships. Discussing any concerns or changes with your partner can reduce anxiety and help you both adapt to any temporary challenges during treatment.

Review other medications: Some drugs commonly prescribed for diabetes-related complications or other conditions—such as certain antidepressants (SSRIs/SNRIs), blood pressure medications (beta-blockers, thiazides), spironolactone, finasteride, opioids, or antipsychotics—can affect sexual function. A medication review with your GP or pharmacist may identify other contributing factors.

Contraception and pregnancy planning: If you are using oral contraceptives, use additional barrier contraception or consider non-oral methods during the first 4 weeks of treatment and after each dose increase. Mounjaro is not recommended during pregnancy or breastfeeding. If you are planning pregnancy, discuss the timing of discontinuation with your healthcare provider.

Be patient with your body: Adjusting to a new medication, particularly one that causes significant metabolic and weight changes, takes time. Many side effects, including fatigue and gastrointestinal symptoms, improve as your body adapts to treatment.

When to Speak to Your GP About Sexual Side Effects

While sexual side effects are not commonly reported with Mounjaro, any persistent or distressing changes in sexual function warrant a conversation with your GP or diabetes specialist nurse. Do not stop taking Mounjaro without medical advice, as this may lead to worsening glycaemic control or weight regain.

You should contact your GP if:

• Sexual difficulties are causing significant distress or affecting your relationship

• You experience new or worsening erectile dysfunction, loss of libido, or difficulties with arousal or orgasm

• Symptoms persist beyond the dose escalation period (often within the first 4-12 weeks) or develop later in treatment

• You have concerns about whether Mounjaro is the right treatment for you

• You are experiencing other troublesome side effects alongside sexual changes

Seek urgent medical attention if you experience:

• An erection lasting more than 4 hours (priapism)

• Chest pain or breathing difficulties during sexual activity

• Severe genital pain, ulcers, unusual discharge, or bleeding

• Sudden genital numbness or new neurological symptoms

Your GP can conduct a thorough assessment to identify potential causes, which may include:

• Reviewing your medication regimen to identify other drugs that may contribute to sexual dysfunction

• Assessing diabetes control and complications such as neuropathy or vascular disease

• Checking hormone levels if clinically indicated, based on your symptoms and medical history

• Evaluating psychological factors such as depression, anxiety, or relationship issues

• Considering referral to specialist services, such as endocrinology, urology, sexual health clinics, or psychosexual therapy, if appropriate

It is important to remember that sexual health is a legitimate medical concern and an integral part of overall wellbeing. Healthcare professionals are accustomed to discussing these issues and can provide evidence-based advice, reassurance, and treatment options tailored to your individual circumstances.

If you suspect Mounjaro may be causing side effects, you can report these through the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk or via the Yellow Card app.

Frequently Asked Questions