Mounjaro and anhedonia: why some people feel flat, and what the evidence says

Reports of low mood and suicidal thoughts in people using GLP-1 medicines prompted formal safety reviews in 2023. The European Medicines Agency’s safety committee concluded in April 2024 that the available evidence did not support a causal association between GLP-1 receptor agonists and suicidal or self-injurious thoughts and actions.^[4] The MHRA reached the same conclusion for the UK in September 2024, extending it to depression, and said no change to the product information was warranted while it continued to monitor.^[3]

Two caveats. First, both reviews examined exenatide, lixisenatide, liraglutide, dulaglutide and semaglutide. Mounjaro’s active ingredient, tirzepatide, acts on the GLP-1 receptor too, but it was not named in those reviews. Second, an absence of proven causation is not proof of no effect for every individual; that is why the regulators keep watching, and why a pharmacovigilance analysis published in 2026 still found depression, anxiety and suicidal ideation among the most frequently reported psychiatric events for this class while noting that regulators have not confirmed a causal relationship.^[5] If you think Mounjaro has affected your mood, you can report it through the MHRA Yellow Card scheme, which is exactly how these signals are picked up.^[6]

Food was doing more than feeding you

For many people, eating is comfort, reward, celebration and a way of getting through a hard day. Mounjaro removes much of the drive to eat and, for some, the pleasure of it. If food was your main source of reward, losing it can leave a gap that feels like flatness until other sources of pleasure fill it. Our emotional eating guide covers this in depth.

You may be eating too little

Very low intake leaves the body short of energy and the brain short of fuel. The result can be low motivation, poor concentration and a blunted mood that is really under-eating. Skipping meals because you are not hungry, rather than eating small regular amounts, is one of the most common patterns on treatment. See eating well on Mounjaro.

Fatigue and poor sleep

Tiredness is a listed side effect of Mounjaro,^[1] and persistent tiredness can be hard to separate from low mood. Disturbed sleep, whether from reflux, needing the toilet or simply a changed routine, compounds it. Read why you feel tired on Mounjaro.

Alcohol has dropped away

Many people find they want to drink less on Mounjaro. If evenings used to be structured around a drink, the absence can feel like a loss even when it is good for you. See Mounjaro and alcohol.

The change itself

Rapid weight loss changes how you look, how people treat you, how clothes fit and how you think about yourself. Big changes, even wanted ones, take emotional adjustment. Some people also carry the weight of other people’s comments; our stigma guide is written for that.

Something unrelated

Low mood and anhedonia have many causes that have nothing to do with a weight-loss medicine: thyroid problems, low iron or vitamin levels, other medicines, life events, and depression itself. Starting a new treatment does not make these less likely. This is why a GP review matters if the feeling persists.

• Keep a two-week note of mood out of 10, what you ate, how you slept and whether the flatness is about food only or wider.
• Eat regularly even without appetite. Small meals with protein at each one are the usual advice; a prescriber or dietitian can tailor it.
• Rebuild reward deliberately. Plan things that used to give you pleasure that are not food, and notice whether they still land.
• Talk to your prescriber and tell them exactly what you have noticed and when it started relative to your doses. They can review dose, titration pace, nutrition and other medicines.
• See your GP if the flatness is persistent, spreading beyond food, or affecting work, relationships or sleep. NHS talking therapies can be self-referred without a GP.^[7]

Is anhedonia a known side effect of Mounjaro?

No. It is not listed in the UK patient leaflet or the Summary of Product Characteristics. People do report a flat feeling, particularly around food, and reports are how regulators monitor safety, but it is not a recognised adverse effect at present.

Does Mounjaro cause depression?

Regulators in the UK and Europe reviewed GLP-1 medicines in 2023 and 2024 and concluded the evidence does not establish a causal link with depression, suicidal thoughts or self-harm. Those reviews did not name tirzepatide specifically, and monitoring continues. If your mood has changed, take it seriously and speak to your GP regardless of the cause.

Why does food not give me any pleasure any more?

Mounjaro reduces appetite and, for many people, the pull towards food. If eating was also comfort or reward, losing that can feel like a loss until other sources of enjoyment replace it. Eating too little can make everything feel flatter as well.

Will it pass?

Many people say the food-related flatness settles as they adjust and find new routines, but there is no reliable evidence on timing and no guarantee. A flat feeling that persists, spreads beyond food or worsens should be reviewed rather than waited out.

Should I stop Mounjaro if I feel flat?

Not on your own. Speak to your prescriber, who can look at dose, pace, nutrition and other causes, and to your GP if the feeling is persistent. If you and your clinicians decide a pause or a change is right, they can guide it.