Mounjaro Side Effects
Posted on September 30, 2026 by Sally-Anne Turner
Does This GLP-1 Worsen Depression?
Have you been on social media and seen reports about Mounjaro side effects relating to mental health?
There has been a lot of talk online about how weight loss medications can allegedly worsen pre-existing mental health issues. Indeed, this is often why many online pharmacies and even clinical trials will not give the green light for people who have mental health issues to take these medications.
However, given that as many as 1.8 million people in England experience depression (Adult Psychiatric Morbidity Survey, 2023/2024), this denial of access to treatment can be rather restrictive.
When you come to the Bodyline Clinic, our team will take the time to assess both your physical and mental wellbeing. We will not dismiss you outright for treatment with Mounjaro, or any of our other GLP-1s. Our clinical team is always eager to help those who have a complex medical history to reach their weight loss goals.
Here, we will take a look at the weight loss medication Mounjaro and assess whether or not it may worsen pre-existing mental health issues like depression or even cause them to occur. We will also consider what this may mean for people exploring weight loss medication UK options when they already have a mental health condition.
What is Depression?
Let’s start with a quick definition of depression.
“Depression is a mental health condition that involves a persistent low mood or loss of interest and enjoyment in activities. It can affect daily life, relationships, and overall well-being.”
Antidepressants, like selective serotonin reuptake inhibitors (SSRIs), are a widely prescribed medication in England, with around 5.47 million people receiving an SSRI prescription in 2024/25. SSRIs are commonly used to treat depression, but the NHS prescribing data does not specify the condition for which each prescription was issued.
Key symptoms of depression to keep an eye on include:
- A persistent low mood or sadness that lasts more than two weeks.
- Loss of pleasure or interest in activities you once enjoyed (anhedonia).
- Changes in appetite or sleep patterns. Sleeping too much or too little, with appetite fluctuations.
- Fatigue, feeling slow or having low energy levels.
- Struggling with indecision.
- Feeling worthless, feeling excessively guilty or hopeless about the future.
- Recurrent thoughts of death or self-harm.
As always, if you note at any time during your GLP-1 treatment with Mounjaro that you are experiencing depression, you should contact your prescriber. If you are having thoughts of hurting yourself or of ending your life, please seek emergency medical treatment. Call 999 or go to A&E.
Weight Loss Meds and Worsening Mental Illness
So, why does Mounjaro have such a link to mental health issues?
There are a few reasons for this. Some are potential misunderstandings. Others may have a more medical basis and may require clinical review and further treatment.
Adjustment and Blood Sugar
When you start taking any GLP-1, and especially Mounjaro, you will need to consider an adjustment period. This can happen as you adapt to the new medication, as well as the lifestyle changes needed to maintain Mounjaro weight loss.
If you keep a mood diary or use online screening tools like the PHQ-9 for depression, this can help you keep track of mood changes over time. It can also help you distinguish between temporary and longer-lasting mood changes. Remember that the PHQ-9 is a screening tool. It is not a diagnostic instrument.
When you are taking Mounjaro alongside insulin or sulfonylureas, it may be wise to keep a combined mood diary alongside a blood glucose diary. Hypoglycaemia can sometimes look like anxiety or even trigger anxiety symptoms.
Brain Gut Connection
As mentioned in our Mounjaro for Weight Loss piece, tirzepatide (Mounjaro) mimics two gut hormones, GLP-1 and GIP. These regulate blood sugar and appetite.
This makes for an immense physical impact on appetite. However, the GLP-1 receptors which are being targeted are not restricted to the stomach. Research has found them scattered in the brain, in areas like the parietal cortex, hypothalamus, and medulla. These are regions involved in appetite signalling but also mood regulation and reward processing.
So, when GLP-1 pathways are targeted in the body, researchers are also interested in whether these treatments could have effects on processes within the brain. However, the presence of GLP-1 receptors in the brain does not by itself establish that Mounjaro causes changes in mood.
Comfort Eating
Our team at the Bodyline Clinic have already written a blog on comfort eating and its role in mental health.
Remember that, as GLP-1s like Mounjaro silence food noise, the underlying psychological issues hidden by this behaviour may come to light. This can lead to depression appearing to get worse. Simply put, if food has previously been used as a coping mechanism, changes in eating behaviour may mean that underlying emotional difficulties become more noticeable.
Does Mounjaro Cause Depression?
Worsening underlying mental states temporarily is one thing. Causing them is another. And we know that if you are already worried about embarking on your weight loss journey, the last thing you want to think about is becoming depressed.
As we mentioned earlier, social media contains many reports from people saying that taking Mounjaro caused them to become depressed.
These are, of course, anecdotal. So, what does the data say? Available evidence from clinical research does not currently support a causal association between GLP-1 medicines and depression, suicidal ideation or suicide.
Let’s look at one of the largest relevant analyses. A 2026 post-hoc analysis of SURMOUNT-1, -2 and -3 involved 4,056 people. At 72 weeks, depressive symptom scores were slightly lower with tirzepatide than with placebo, suggesting that Mounjaro did not increase depressive symptoms in this study population. Importantly, participants with known major psychopathology were excluded, so these Mounjaro results cannot automatically be applied to people with significant pre-existing psychiatric illness.
An observational study from 2026 noted that GLP-1 medications as a class had higher rates of depression compared to some other diabetes medications. In particular, HR 1.19 versus SGLT2 inhibitors. Again, this doesn’t exclusively say that Mounjaro causes depression, as this looked at GLP-1 medicines as a broader class.
Pharmacovigilance research using the World Health Organisation (WHO) VigiBase has also investigated reporting signals for depressed mood and suicidal thoughts involving GLP-1 medicines, including tirzepatide. However, spontaneous reporting signals cannot establish that a medication caused the reported event.
Based on the available data, there is currently no established causal link showing that taking Mounjaro causes depression. However, each person is different, and each weight loss experience is too.
Bodyline and Mounjaro Side Effects
What sets our team at the Bodyline Clinic apart is that we don’t simply write you a quick prescription after a quick consultation.
Our team will take the time to get to know you and, if you have underlying mental health issues, we will offer you support with your weight loss journey.
Your treatment plan may also depend on factors including your starting health, NHS BMI classification, existing medications and whether you have previously used another GLP-1. These considerations can also influence which Mounjaro doses may be appropriate and how your treatment is monitored.
People considering Mounjaro vs Wegovy may also be concerned about their different safety profiles. Looking at Wegovy vs Mounjaro side effects with a clinician can help put potential risks into the context of your individual medical and mental health history.
We cannot comment on exactly how we may manage your treatment but generally, we may recommend steps such as:
- Increased monitoring. This may be more suited to symptoms of depression that are mild, or if we identify other factors that may be contributing to a worsening of symptoms.
- Psychological support. We cannot offer this directly. However, we can recommend external services that may offer cognitive behavioural therapy (CBT). This may be available through NHS Talking Therapies, with self-referral possible in many areas.
- Antidepressants (SSRIs). These will be managed by your GP. Your wider medication history can be considered as part of your clinical assessment and ongoing monitoring.
- Dose adjustment. If you experience significant side effects, your clinical team can assess whether your treatment or dose needs reviewing.
- Referrals. If your case is more complex, referral to an appropriate healthcare professional or specialist service may be recommended.
Clinical support can also be important when coming off Mounjaro, particularly if you are concerned about maintaining weight loss or managing changes in appetite after treatment.
When you come to the Bodyline Clinic, we will take the time to work with you to assess your health. This will allow us to establish a baseline and to better monitor your health throughout your GLP-1 treatment. Our dedicated clinical team has over 18 years of experience and has helped over 100,000 people across the UK to lose weight, as well as having a 95% 5 star reviews on Trustpilot. We always aim to help as many people as possible who may have complex health conditions and want to lose weight medically.
So, please contact our team today to start your weight loss journey.
FAQs
When do Side Effects of Mounjaro Start?
Mounjaro side effects often start soon after treatment starts or following a dose increase. Common side effects include gastrointestinal issues (nausea, vomiting, diarrhoea) as your body adjusts. Some people have noted an increase in depressive symptoms and, if you note these, you should talk to your prescriber.
Can Mounjaro Cause Mood Swings?
The current evidence has not stated that Mounjaro directly causes mood swings or depression. However, there is some data that suggests that depression may become more apparent if you have a pre-existing diagnosis of depression.
Does Mounjaro Depression go Away?
There is no clinical data that states that Mounjaro causes depression. So, it is hard to say if and when Mounjaro depression goes away. If you note depression during this GLP-1 treatment, you should talk to your prescriber, as they may be able to offer additional support.
