If you've noticed changes in your mood, increased anxiety, or feelings of depression since starting Mounjaro, you're not alone.

Mounjaro (tirzepatide) is a once-weekly injection originally developed for type 2 diabetes that has become one of the most prescribed anti-obesity medications in the UK. Mental health side effects aren't prominently featured in the official literature, but reports from people who are overweight or living with obesity and taking GLP-1 (glucagon-like peptide-1) medications have raised questions about the connection between these drugs and mood changes.

The relationship between Mounjaro and depression isn't fully understood. Some people report mood changes whilst taking tirzepatide, though it's often difficult to separate medication effects from the psychological impact of rapid weight loss, dietary changes, and the experience of treatment. If you're experiencing mental health symptoms, they deserve attention regardless of the cause.

Key takeaways

Clinical trials for Mounjaro did not identify depression as a common adverse effect, and the European Medicines Agency found no causal link between GLP-1 medications and suicidal thoughts after a 2024 review

Multiple factors can affect mood during treatment, including reduced calorie intake, hormonal changes from weight loss, and the psychological complexity of major body changes

If you're experiencing persistent low mood, anxiety, or thoughts of self-harm, speak to your GP promptly and don't stop Mounjaro without medical guidance

Mental health support is available through NHS Talking Therapies (self-referral), your GP, or crisis services including Samaritans (116 123)

A person sitting thoughtfully with a warm cup of tea, looking contemplative but calm, in a comfortable setting with soft lighting.

Does Mounjaro cause depression?

The honest answer is: we don't know for certain. Depression isn't listed as a common adverse effect in Mounjaro's clinical trials, but real-world reports and pharmacovigilance data (systems that track medication side effects after approval) have flagged mental health concerns with GLP-1 medications. You can read the full list of reported side effects in the official Mounjaro prescribing information.

Several factors make this complicated:

The evidence is mixed

Clinical trials for Mounjaro didn't show significantly higher rates of depression compared to placebo. The SURMOUNT trials (the main clinical trials for tirzepatide in obesity treatment) actually showed improvements in mental health and quality-of-life measures. However, clinical trials often exclude people with existing mental health conditions and may not capture effects that develop over longer periods or in diverse populations.

Post-marketing surveillance (monitoring after a drug is widely available) has identified reports of depression, anxiety, and suicidal thoughts in some people taking GLP-1 medications. The European Medicines Agency (EMA) launched a review in July 2023 following reports from Iceland.

After evaluating clinical trials, post-marketing surveillance, and published studies, the EMA's Pharmacovigilance Risk Assessment Committee concluded in April 2024 that the available evidence does not support a causal association between GLP-1 medications and suicidal thoughts or self-harm.

Correlation isn't causation

People taking Mounjaro are going through significant changes: rapid weight loss, altered eating patterns, hormonal shifts, and major lifestyle adjustments. Any of these could affect mood independently of the medication itself.

Weight loss, despite being desired, can be psychologically complex. Body image issues, loose skin, changes in how others treat you, and shifts in your relationship with food can all trigger emotional responses.

Individual variation matters

Some people report improved mood on Mounjaro, possibly due to better health, increased confidence, or reduced inflammation (which is linked to depression). Others report worsening mood. Individual responses vary significantly.

Why might Mounjaro affect mental health?

Several mechanisms could theoretically connect Mounjaro to mood changes, though research is ongoing.

An infographic showing six factors that may affect mental health during Mounjaro treatment: brain chemistry, reduced calories, blood sugar changes, sleep disruption, hormonal shifts, and psychological factors.

Effects on brain chemistry

GLP-1 receptors exist not just in your gut and pancreas, but also in your brain, including regions involved in mood regulation such as the prefrontal cortex and amygdala. Mounjaro belongs to a class of medications called incretins (hormones that your body naturally produces to regulate blood sugar and appetite). As a dual GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptor agonist, it works on two appetite-regulating hormones instead of one. Its effects on brain receptors in the stomach and throughout the digestive system could theoretically influence mood and emotional regulation.

Research suggests GLP-1 medications can affect brain regions involved in emotional regulation, though the clinical significance of this isn't well understood.

Reduced calorie intake

Severely restricting calories is a known trigger for low mood, irritability, and cognitive changes. If you're eating significantly less on Mounjaro, this could affect your mental state, particularly if you're not getting adequate nutrition.

Your brain needs fuel to produce neurotransmitters like serotonin and dopamine that regulate mood. Inadequate intake can disrupt this process. Some people also notice changes in taste whilst taking Mounjaro, which can make eating less enjoyable and further reduce intake.

Blood sugar fluctuations

Whilst Mounjaro generally stabilises blood sugar (which is why it's also used in type 2 diabetes management), the adjustment period can involve fluctuations. Low blood sugar (hypoglycaemia) can cause symptoms that mimic anxiety or depression, including irritability, confusion, headache, and mood swings.

Sleep disruption

Some people experience insomnia or sleep changes on Mounjaro. Poor sleep is strongly linked to depression and anxiety, as outlined by NHS guidance on mental wellbeing. If the medication is affecting your sleep, this could indirectly impact your mental health.

Hormonal changes

Rapid weight loss affects hormone levels, including oestrogen (which is produced by fat tissue) and cortisol (the stress hormone). These hormonal shifts can influence mood, particularly in women who may also experience menstrual changes.

The psychological weight of weight loss

Weight loss isn't purely physical. Your weight loss journey can bring up complex emotions that affect your mental health, even when you're achieving your weight loss goals. Many people experience:

Grief for your former self or former eating habits
Anxiety about regaining weight
Complicated feelings if weight loss doesn't solve the problems you expected it to
Difficulty adjusting to a changing body and identity
Stress from managing side effects and treatment

These psychological factors can contribute to low mood even when the medication itself isn't directly causing depression.

Signs to watch for

Being aware of mental health changes helps you address them early. Watch for:

A checklist showing four categories of mental health symptoms to monitor: depression symptoms, anxiety symptoms, mood swings, and brain fog, each with an identifying icon.

Depression symptoms

Persistent sadness or emptiness lasting more than two weeks
Loss of interest in activities you usually enjoy
Changes in sleep (too much or too little)
Fatigue or loss of energy beyond normal Mounjaro tiredness
Feelings of worthlessness or excessive guilt
Difficulty concentrating or making decisions
Thoughts of death or suicide (seek immediate help)

Anxiety symptoms

Excessive worry that's hard to control
Feeling restless or on edge
Difficulty concentrating
Irritability
Muscle tension
Sleep problems
Physical symptoms like racing heart, sweating, trembling

Mood swings

Unpredictable emotional shifts
Irritability that seems disproportionate
Feeling emotionally "flat" or numb
Crying more easily than usual

Brain fog

Difficulty concentrating
Memory problems
Feeling mentally "slow" or cloudy
Trouble finding words

What to do if you're experiencing mental health changes

Mental health symptoms deserve attention, whether or not they're directly caused by Mounjaro.

A process diagram showing seven steps for managing mental health changes: acknowledge your experience, talk to your provider, focus on nutrition, prioritise sleep, stay connected, move your body, and seek professional support.

Don't dismiss your experience

It's easy to tell yourself you're overreacting or that you should just be grateful for the weight loss. Your mental health matters. If something feels wrong, take it seriously.

Talk to your healthcare provider

Let your prescriber know about any mental health changes. They can:

Assess whether symptoms might be medication-related
Check for other contributing factors (thyroid issues, nutritional deficiencies)
Adjust your treatment plan if needed
Refer you for mental health support

Be honest about what you're experiencing. Mental health symptoms aren't a sign of weakness or failure.

Ensure adequate nutrition

If you're eating very little, try to increase your intake. Focus on:

Adequate protein: aim for 1.0–1.2g per kilogram of body weight daily during weight loss to support neurotransmitter production (for someone weighing 80kg, this means roughly 80–100g daily)
Complex carbohydrates (help with serotonin production)
Omega-3 fatty acids (linked to mood regulation)
Regular meals rather than skipping food
Adequate hydration: aim for at least 2 litres of water daily, as dehydration can worsen fatigue and mood

Sometimes mood improves simply by eating more, even if you're not hungry.

Prioritise sleep

Poor sleep significantly worsens mood. If you're struggling with sleep:

Maintain consistent sleep and wake times
Create a relaxing bedtime routine
Limit screens before bed
Avoid caffeine after midday
Keep your bedroom cool and dark

If insomnia persists, speak to your doctor.

Stay connected

Social isolation worsens depression. Even when you don't feel like it, try to:

Maintain contact with friends and family
Engage in activities you usually enjoy
Join support groups (online or in-person) for people on weight loss medication
Talk to someone you trust about how you're feeling

Move your body

Exercise is one of the most effective interventions for depression. A 2024 systematic review and meta-analysis of 218 studies found that walking, jogging, yoga, and strength training showed significant benefits for depression, with effects comparable to psychotherapy and antidepressants.

Even gentle activity like walking can help. Aim for some form of movement most days, even if it's brief.

Seek professional support

If symptoms are significant or persistent, consider:

Speaking to your GP about mental health support
Self-referring to NHS Talking Therapies (formerly known as IAPT) for free NHS counselling and therapy
Private counselling or therapy
Support groups for people managing weight or using GLP-1 medications

You don't have to manage this alone.

When to seek urgent help

Some symptoms require immediate attention. Seek urgent help if you experience:

Thoughts of suicide or self-harm
Thoughts of harming others
Severe anxiety or panic attacks
Psychotic symptoms (hallucinations, delusions, paranoia)
Complete inability to function
Call 999 if you're in immediate danger
Call Samaritans: 116 123 (free, 24/7)
Text SHOUT to 85258 (free crisis text line)
Go to A&E if you need immediate support

In a crisis:

Crisis support contacts displayed clearly: 999 for emergencies, Samaritans at 116 123, and text SHOUT to 85258.

Don't wait to see if things improve on their own if you're having thoughts of suicide or self-harm.

Should you stop Mounjaro if you feel depressed?

Don't stop any medication without discussing it with your prescriber. Suddenly stopping Mounjaro could affect your blood sugar control and weight management.

If you're experiencing significant mental health symptoms, your prescriber might recommend:

Continuing Mounjaro whilst adding mental health treatment
Adjusting your dose
Pausing treatment temporarily to see if symptoms improve
Switching to an alternative medication

The right approach depends on your individual situation, the severity of your symptoms, and your overall health goals.

Mental health support alongside weight loss

Weight loss treatment works best when it addresses the whole person, not just the number on the scale. If you're struggling emotionally, this isn't a failure of willpower or a sign you shouldn't be on medication.

Many people benefit from mental health support alongside weight loss treatment. This might include:

Therapy to address emotional eating patterns
Support for body image concerns
Help adjusting to physical changes
Treatment for underlying depression or anxiety
Support groups with others on similar journeys

Your mental health is as important as your physical health. Both deserve care and attention.

The bottom line

The connection between Mounjaro and mental health isn't fully understood, but some people do experience mood changes whilst taking the medication. These could be caused by the drug itself, by reduced calorie intake, by the hormonal and psychological effects of rapid weight loss, or by a combination of factors.

If you're experiencing depression, anxiety, or other mental health symptoms, take them seriously. Speak to your healthcare provider, ensure you're eating adequately, prioritise sleep, and seek mental health support if needed.

Your mental wellbeing matters as much as your physical health.

Finding the right provider

If you're struggling with mood changes, having a provider who actually checks in on you matters. Some UK providers include regular clinical reviews and proactive mental health screening, while others offer little beyond the prescription itself — and switching is easier than most people think.

Frequently asked questions

Should I tell my doctor about mood changes on Mounjaro?

Yes, always. Your prescriber needs to know about any mental health changes to provide appropriate care. They can assess whether symptoms might be medication-related and ensure you get support.

Will stopping Mounjaro help my depression?

It depends on the cause. If symptoms are directly medication-related, they might improve after stopping. If they're related to weight loss, dietary changes, or other factors, stopping Mounjaro might not help. Don't stop medication without medical guidance.

Can Mounjaro cause anxiety?

Some people report increased anxiety on GLP-1 medications. This could relate to the medication itself, blood sugar changes, reduced food intake, or the stress of managing treatment and body changes. Discuss anxiety symptoms with your healthcare provider.

Why do I feel sad about losing weight?

Weight loss can bring complex emotions, including grief for former eating habits, fear of regaining weight, identity changes, and disappointment if weight loss doesn't solve the problems you expected. These feelings are valid and don't mean something is wrong with you.

Can not eating enough cause depression?

Yes. Severe calorie restriction can cause low mood, irritability, brain fog, and depression-like symptoms. Your brain needs adequate fuel to function properly. If you're eating very little on Mounjaro, try to increase your intake.

Where can I get mental health support in the UK?

Options include your GP, NHS Talking Therapies (you can self-refer for free NHS counselling), private counselling, Samaritans (116 123), and crisis text line (text SHOUT to 85258). The NHS mental health hub has further information on conditions and support available. Don't hesitate to reach out if you're struggling.

How long do mood changes last on Mounjaro?

If mood changes are related to the medication, many people find symptoms improve within 2–4 weeks as your body adjusts to each dose. However, if changes are related to the psychological aspects of weight loss or inadequate nutrition, they may persist until those underlying factors are addressed. Speak to your GP if low mood continues for more than two weeks.

Is it safe to take antidepressants with Mounjaro?

There are no known significant interactions between Mounjaro (tirzepatide) and most antidepressants. Many people successfully take both medications together. However, always inform your prescriber about all medications you're taking so they can monitor you appropriately and adjust doses if needed.