Can Mounjaro make you tired? If you are feeling tired or sluggish you’re not alone. Fatigue is one of the common Mounjaro side effects, affecting between one in 10 and one in 100 patients.

As it’s still a relatively new medication, we don’t yet know why Mounjaro causes fatigue. However, there are several possible explanations for it. And the good news is there are steps you can take to feel more energised.

To help you feel your best during your treatment, this article explores the possible links between Mounjaro (tirzepatide) and fatigue, and provides practical tips to combat exhaustion, as you lose weight and build long term health gains.

Mounjaro and Fatigue: Why Am I Feeling Drained?

There are currently no clinical studies that explain why you might lack energy on the medication. However, there are some theories that could explain why you feel tired and lethargic while using GIP and GLP-1 receptor agonists, like Mounjaro.

Here are some of possible explanations:

You’re Eating Less

Mounjaro reduces your appetite and makes you feel full sooner, which is why it’s so effective for weight loss. However, if you eat too little on Mounjaro, this might contribute to fatigue.

“Mounjaro often leads to a significant decrease in food intake, which can lead to consuming fewer nutrients, ultimately impacting your energy levels,” Laura Perez, Lead Dietician at Simple Online Pharmacy, explains.

Mounjaro Impacts Your Hormones

Mounjaro injections affect your metabolism by influencing hormones that regulate blood sugar and appetite. These metabolic changes might make you feel tired, especially during the initial adjustment period.

Side Effects Can Cause Fatigue

Potential side effects include diarrhoea, being sick and nausea, which can increase the risk of dehydration and electrolyte imbalances. Both of which can cause tiredness and fatigue.

Mounjaro Might Affect Your Sleep Cycle

Mounjaro works by sending signals to the hypothalamus, an area of your brain that produces hormones that control hunger, body temperature and mood.

The hypothalamus also regulates sleep and wakefulness, so it’s possible the medication could be impacting your sleep-wake cycle.

Your Blood Sugar is Low

While Mounjaro doesn’t directly cause hypoglycaemia (low blood sugar), there is some association between GLP-1 medications and low blood sugar.

If you’re using GLP-1 pens to treat type 2 diabetes alongside sulphonylurea and/or insulin medication, low blood sugar is a common drug interaction. Malnutrition can also lead to low blood sugar, so you could experience hypoglycaemia if you’re undereating on Mounjaro.

Symptoms of low blood sugar may include feeling tired or weak, as well as headaches, dizziness and feeling cold and hungry. If you suspect you have low blood sugar, get in contact with your healthcare provider.

Tips to Fight Fatigue on Mounjaro

If you’re experiencing Mounjaro fatigue, focus on making small adjustments to support your overall wellbeing. As you incorporate the following strategies, you’ll likely begin to feel better. 

Eat Nutrient-Dense Food

Eating enough nutrient-dense foods is one of the best ways to combat fatigue.

“Even if you aren’t able to eat large portions, prioritise nutrient-dense foods to provide essential vitamins and minerals that help maintain your energy levels,” Laura advises.

“Incorporate a variety of fruits, vegetables, whole grains, lean proteins and healthy fats into your meals. This way you can ensure you’re getting the necessary nutrients to support your body.”

These foods will provide a steady energy source throughout the day. Avoid simple sugars and highly processed foods. They can cause rapid spikes and crashes in energy, which is exactly what we want to avoid.

Exercise Regularly

As well as boosting energy levels, improving your mood and promoting better sleep, some studies have found that gentle exercise can help combat fatigue.

Of course, exercise might seem like the last thing you want to do when feeling tired. But some light exercise every day can make you feel more awake and energised. 

Pushing yourself too hard can make you even more tired. Listen to your body and avoid overly intense workouts.

Start small, with gentle exercises like walking, yoga or swimming, and gradually increase the intensity and duration of your workouts as your energy levels improve.

Build a Sleep Routine

“Prioritise rest and make sure you’re getting enough sleep as recovery is vital for maintaining your overall wellness,” Laura says.

A consistent sleep routine can regulate your body’s natural sleep-wake cycle, which is “necessary to replenish and heal the body to ensure that it can function properly”. This will help you recharge and feel energised the next day.

Here are some steps you can take for better sleep:

  • Go to sleep and wake up at the same time every day.
  • Get seven to nine hours of sleep every night.
  • Create a relaxing bedtime routine that includes, for example, reading a book or meditating.
  • Avoid bright screens, especially blue screens such as smartphones and laptops.
  • Avoid consuming caffeine within four to six hours before bedtime.

Manage Stress Levels

When stress becomes chronic, it can drain your energy and intensify fatigue.

Techniques like meditation, deep breathing exercises, hobbies or gentle exercise can help you manage stress levels.

Stay Hydrated

Common side effects of Mounjaro like nausea, vomiting and diarrhoea can cause dehydration. A symptom of dehydration is tiredness, this happens because your tissues aren’t getting the amount of fluid they need to function.

So drink plenty of water to prevent dehydration-related fatigue. If you have persistent vomiting and/or diarrhoea, let your healthcare provider know.

Key Takeaways

  • What Causes Fatigue on Mounjaro? While the exact cause is unknown, potential reasons may include reduced food intake, hormonal changes, side effects like nausea and dehydration, sleep cycle disruptions and lower blood sugar levels.
  • Eat Enough Nutrient-Dense Food: Prioritising nutrient-dense foods and a balanced diet is essential for maintaining energy levels, as reduced food intake and blood sugar fluctuations can lead to fatigue.
  • Exercise Regularly and Manage Stress: Gentle exercise can help boost energy, improve mood and promote better sleep. Chronic stress can drain your energy and worsen fatigue but techniques like meditation can help you manage stress.
  • Prioritise Rest: Get enough sleep and maintain a consistent sleep schedule. Going to bed at the same time each night, minimising screen time before bed and avoiding caffeine late in the day can help regulate your sleep cycle and reduce fatigue.
  • Stay Hydrated: Side effects like nausea, vomiting and diarrhoea, can cause dehydration, which can worsen fatigue. Make sure you drink plenty of water and stay hydrated throughout the day.
  • Get Support: If you suspect you have low blood sugar or are experiencing persistent vomiting and diarrhea, get advice from your healthcare provider. If you’re a patient with Simple, call us on 0141 774 5023.

References 

Mendoza, F., Parsiani, R., 2019. Impact of tirzepatide in a patient with type 1 diabetes and obesity: A case report. Journals of the American Pharmacists Association. 63(6), pp.1821-1825. [online]. Available from: https://pubmed.ncbi.nlm.nih.gov/37604405/.

Whyte, M. (2023). Mounjaro has been authorised for weight loss in the UK – here’s how it compares to Wegovy. [online] The Conversation. Available at: https://theconversation.com/mounjaro-has-been-authorised-for-weight-loss-in-the-uk-heres-how-it-compares-to-wegovy-217413.

National Institute of Neurological Disorders and Stroke (2024). Brain basics: Understanding sleep. [online] National Institute of Neurological Disorders and Stroke. Available at: https://www.ninds.nih.gov/health-information/public-education/brain-basics/brain-basics-understanding-sleep.

Reddy, S., Sharma, S. and Reddy, V. (2023). Physiology, Circadian Rhythm. [online] Nih.gov. Available at: https://www.ncbi.nlm.nih.gov/books/NBK519507/.

Puetz, TW., Flowers, SS., O’Connor, PJ., 2008. A randomized controlled trial of the effect of aerobic exercise training on feelings of energy and fatigue in sedentary young adults with persistent fatigue. Psychotherapy and Psychosomatics. 77(3), pp.167-74. [online]. Available at: https://pubmed.ncbi.nlm.nih.gov/18277063/

Kranz, R. (2024). Symptoms of dehydration: What they are and what to do if you experience them. [online] Harvard Health. Available at: https://www.health.harvard.edu/staying-healthy/symptoms-of-dehydration-what-they-are-and-what-to-do-if-you-experience-them.