Concerns about sexual side effects are common when starting new medications, particularly those affecting metabolism and weight. Mounjaro (tirzepatide) is a dual GIP/GLP-1 receptor agonist licensed in the UK for type 2 diabetes treatment. Whilst erectile dysfunction is a significant concern for many men with diabetes, current clinical evidence does not establish a direct link between Mounjaro and impotence. Understanding the relationship between tirzepatide, metabolic health, and sexual function requires careful consideration of the available evidence, the multifactorial nature of erectile dysfunction, and the potential benefits of improved glycaemic control and weight loss on overall sexual health.

Understanding Mounjaro and Its Primary Effects

Mounjaro (tirzepatide) is a prescription medication licensed in the UK for the treatment of type 2 diabetes mellitus. It belongs to a novel class of medicines known as dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonists. By activating both of these incretin hormone receptors, Mounjaro works through multiple complementary mechanisms to improve glycaemic control and promote weight loss.

The medication functions primarily by enhancing insulin secretion in response to elevated blood glucose levels, whilst simultaneously suppressing glucagon release when it is not needed. Clinical trials such as SURPASS-2 have shown that tirzepatide achieves greater HbA1c reductions and weight loss compared to semaglutide 1 mg. Additionally, tirzepatide slows gastric emptying, which prolongs the feeling of fullness after meals, and acts on appetite centres in the brain to reduce hunger and food intake.

Mounjaro is administered as a once-weekly subcutaneous injection. Treatment starts with 2.5 mg weekly for 4 weeks (initiation dose only), then increases to 5 mg. The dose can be increased by 2.5 mg every 4 weeks or more to 7.5 mg, 10 mg, 12.5 mg, or 15 mg based on individual response and tolerability. Common adverse effects include gastrointestinal symptoms such as nausea, vomiting, diarrhoea, and constipation, which tend to be most pronounced during dose escalation. Patients should be aware of symptoms of pancreatitis (severe abdominal pain that may radiate to the back), which warrant urgent medical review, and the risk of hypoglycaemia when used with insulin or sulfonylureas. Understanding the medication's primary mechanisms is essential when considering any potential effects on other body systems, including sexual function.

Does Mounjaro Cause Impotence? Examining the Evidence

When considering whether Mounjaro causes impotence (erectile dysfunction), it is important to examine the available clinical evidence carefully. There is no official, established link between tirzepatide and erectile dysfunction based on the current body of research. In the pivotal clinical trials that led to Mounjaro's approval—including the SURPASS programme for type 2 diabetes and the SURMOUNT trials for weight management—erectile dysfunction was not identified as a common or significant adverse effect of the medication.

The Summary of Product Characteristics (SmPC) approved by the Medicines and Healthcare products Regulatory Agency (MHRA) does not list impotence or erectile dysfunction among the known side effects of tirzepatide. This regulatory document comprehensively details adverse reactions observed during clinical development, and sexual dysfunction has not been reported at frequencies that would warrant inclusion. It is worth noting that clinical trials systematically monitor and record adverse events, and any signal suggesting a causal relationship would typically be investigated and documented.

However, the absence of evidence is not absolute proof of no effect, and post-marketing surveillance continues to monitor for rare or previously undetected adverse reactions. Individual patients may experience a wide range of effects when taking any medication, and it remains theoretically possible for isolated cases to occur. If erectile dysfunction develops during Mounjaro treatment, it is essential to consider the multifactorial nature of sexual function and explore other contributing factors, rather than immediately attributing the symptom to the medication itself. Healthcare professionals should take any concerns seriously and conduct a thorough assessment to identify the underlying cause.

How Weight Loss and Metabolic Improvements May Affect Sexual Function

Interestingly, the metabolic improvements and weight loss associated with Mounjaro treatment may actually have a positive impact on erectile function rather than a detrimental one. Erectile dysfunction is strongly associated with obesity, type 2 diabetes, and cardiovascular disease—conditions that Mounjaro is designed to address. Research has consistently demonstrated that men with obesity and metabolic syndrome experience higher rates of erectile dysfunction due to endothelial dysfunction, reduced nitric oxide availability, hormonal imbalances (particularly low testosterone), and psychological factors related to body image.

Significant weight loss, such as that achieved with tirzepatide therapy, can lead to improvements in erectile function through several mechanisms. Reducing adipose tissue decreases systemic inflammation and improves vascular health, which is crucial for achieving and maintaining erections. Weight loss is also associated with increased testosterone levels in men with obesity, as excess adipose tissue converts testosterone to oestrogen through the enzyme aromatase. Improved glycaemic control reduces the microvascular and macrovascular complications of diabetes that contribute to erectile dysfunction.

Clinical studies examining lifestyle interventions and bariatric surgery have shown that substantial weight reduction can restore erectile function in many men who previously experienced difficulties. A systematic review published in the Journal of Sexual Medicine found that weight loss interventions were associated with significant improvements in erectile function scores. However, it's important to note that not everyone will experience improvement, and other causes of erectile dysfunction may coexist. Overall, patients taking Mounjaro may experience enhanced sexual function as their metabolic health improves, cardiovascular risk factors diminish, and body composition changes favourably. This potential benefit should be considered when evaluating the overall impact of treatment on quality of life and sexual health.

Other Factors That May Influence Erectile Function During Mounjaro Treatment

When erectile difficulties arise during Mounjaro treatment, it is crucial to consider the multifactorial nature of sexual dysfunction rather than attributing symptoms solely to the medication. Several concurrent factors may influence erectile function in individuals taking tirzepatide:

Underlying health conditions: Type 2 diabetes itself is a major risk factor for erectile dysfunction, affecting 35–75% of men with the condition. Diabetic neuropathy, vascular disease, and endothelial dysfunction all contribute to impaired erectile function. Endocrine disorders such as hypogonadism, hyperprolactinaemia, and thyroid disease can also cause erectile dysfunction. The progression of diabetes or its complications may coincide with starting Mounjaro, creating a temporal association that does not reflect causation.

Concurrent medications: Many patients taking Mounjaro are also prescribed other medications that have established links to erectile dysfunction. These include certain antihypertensives (particularly non-vasodilating beta-blockers and thiazide diuretics), antidepressants (especially selective serotonin reuptake inhibitors), and medications for benign prostatic hyperplasia (particularly 5-alpha-reductase inhibitors, while alpha-blockers have less effect). A comprehensive medication review is essential to identify potential contributors.

Psychological factors: Starting a new medication, concerns about health conditions, and the stress of managing chronic disease can all impact sexual function. Additionally, rapid weight loss and changes in body image may affect self-confidence and sexual desire during the adjustment period. Relationship dynamics and mental health conditions such as depression and anxiety are significant contributors to erectile dysfunction.

Lifestyle factors: Smoking, excessive alcohol consumption, lack of physical activity, and poor sleep quality all negatively affect erectile function. Patients beginning Mounjaro treatment may be addressing multiple health concerns simultaneously, and these lifestyle factors should be evaluated as part of a holistic assessment of sexual health.

When to Seek Medical Advice About Sexual Health Concerns

Patients experiencing erectile dysfunction or other sexual health concerns whilst taking Mounjaro should not hesitate to discuss these issues with their GP or healthcare provider. Sexual health is an important component of overall wellbeing and quality of life, and healthcare professionals are accustomed to addressing these concerns in a sensitive, confidential manner. Early consultation allows for proper assessment and appropriate management.

Seek medical advice if you experience:

• New or worsening erectile dysfunction after starting Mounjaro

• Sudden loss of sexual desire or other changes in sexual function

• Erectile difficulties accompanied by other symptoms such as chest pain, shortness of breath, or leg pain (which may indicate cardiovascular issues)

• Psychological distress or relationship difficulties related to sexual function

• Concerns about whether Mounjaro or other medications may be contributing to sexual problems

Seek urgent medical attention by calling 999 if you experience chest pain or symptoms of a heart attack whilst taking medication for erectile dysfunction. Seek same-day medical assessment for an erection lasting more than 4 hours (priapism), sudden neurological symptoms, or painful penile deformity.

Your healthcare provider will conduct a comprehensive assessment that includes reviewing your medical history, current medications, lifestyle factors, and psychological wellbeing. They may perform a physical examination and order blood tests to evaluate testosterone levels, HbA1c, lipid profile, and thyroid function. According to NICE Clinical Knowledge Summary (CKS) guidance on erectile dysfunction, assessment should include cardiovascular risk stratification using tools such as QRISK, as erectile problems often precede cardiovascular events.

Treatment options for erectile dysfunction are varied and effective, ranging from lifestyle modifications and psychological support to phosphodiesterase-5 (PDE5) inhibitors (such as sildenafil) and other therapeutic interventions. PDE5 inhibitors are contraindicated in patients taking nitrates or riociguat and should be used with caution in those taking alpha-blockers. Do not discontinue Mounjaro without medical advice, as the metabolic benefits of continued treatment likely outweigh any potential concerns. Your healthcare team can work with you to optimise your overall treatment plan whilst addressing sexual health concerns appropriately.

Patients and healthcare professionals should report suspected side effects of Mounjaro or any other medication via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk or in the Yellow Card app).

Frequently Asked Questions