Retatrutide side effects: what the research says so far
Retatrutide is still in clinical trials, so the full range of possible side effects isn’t yet known – especially in the long term. However, early studies have begun to show patterns. Discover what the research says so far.
If approved, retatrutide may be used as a treatment for type 2 diabetes and as a weight loss medication. It would always need to be taken under medical supervision to manage any side effects.
If you’re looking for professional support, and have a BMI over 35, you may be eligible for Oviva’s NHS-funded weight management programme. You’ll receive care from healthcare professionals, guidance to build sustainable healthy habits, and, if appropriate, access to weight loss injections.
Key Takeaways
- Retatrutide is still in trials – early studies show gastrointestinal symptoms and mild injection site reactions.
- Less common side effects may include pancreatitis and changes to heart rhythm.
- Always take weight loss medication under medical supervision to keep treatment safe.
Table of Contents
What is retatrutide and how does it work?
What are the common side effects of retatrutide?
Are there long-term side effects?
Could retatrutide impact sleep or cause fatigue?
What to do if you experience side effects of weight loss medication
Who shouldn’t take retatrutide?
Worried about side effects? You’re not alone, and support is available
What is retatrutide and how does it work?
Retatrutide is a medication currently being tested for type 2 diabetes and weight management. It’s still in clinical trials, which means it isn’t yet available as an approved treatment.
The drug works through a “triple action” mechanism, targeting three key receptors and hormones in the body:
- GLP-1 – helps regulate blood sugar and appetite
- GIP – supports insulin production and metabolism
- Glucagon – influences energy use and fat burning
Because of this, retatrutide is sometimes nicknamed “Triple G.”
By working on these pathways, the medication may help to:
- Control blood glucose levels
- Reduce appetite
- Increase feelings of fullness after meals
- Support fat burning
What I love about Oviva is that I can eat what I want.
What are the common side effects of retatrutide?
Like other GLP-1 medications, such as Wegovy or Mounjaro, the most widely reported side effects with retatrutide so far are gastrointestinal. These include:
- Nausea
- Vomiting
- Diarrhoea
- Constipation
- Bloating
- Abdominal pain
Some gastrointestinal side effects likely happen because the medication slows digestion.
Side effects are most common at higher doses, when increasing the dose or at the start of treatment. They are usually mild and tend to improve over time.
Phase 2 trials have also highlighted other possible side effects, like injection site reactions.
It’s important to only take weight loss injections under medical supervision. This allows healthcare professionals to monitor your reaction to the medication. They may also adjust the dosing schedule based on the severity of side effects.
Can retatrutide affect the heart?
In phase 2 clinical trials, some participants experienced a slight increase in heart rate. This effect was generally mild and more noticeable at higher doses.
A small number of people also reported changes to their heart rhythm (arrhythmias), though none of these were considered serious.
This underlines the importance of only taking weight loss medications under medical supervision, and avoiding unauthorised sources.
What skin-related side effects have been reported?
In clinical testing, around 7% of participants reported skin sensitivity. This included:
- Tenderness
- Pain when being touched
- Sensitivity to pressure or heat
The effects were generally mild to moderate and temporary.
Are there long-term side effects?
Because retatrutide is still in clinical trials, its long-term side effects are not yet fully known.
So far, phase 2 trial results have shown that:
- Around 1% of participants saw temporary increases in liver enzymes, which may signal liver irritation or damage.
- One participant developed pancreatitis (inflammation of the pancreas).
Over time, researchers will gain a clearer picture of the potential long-term risks.
Can it affect hormones?
Retatrutide affects the hormones in your body responsible for appetite regulation and metabolism.
So far, there’s no evidence that retatrutide directly impacts reproductive or thyroid hormones. In fact, it may improve insulin sensitivity.
It should be noted that GLP-1 weight loss treatments have the potential to increase fertility through weight loss and improving insulin resistance. However, it’s not considered safe to become pregnant while taking the medication.
GLP-1 treatments can also reduce the effectiveness of oral contraceptives. If you are prescribed retatrutide, you may need to use another form of contraception, such as a coil or condoms.
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Does retatrutide cause hair loss?
There’s no evidence so far that retatrutide directly causes hair loss, though more research is needed.
There are a small number of hair loss reports for similar weight loss medications. In Wegovy trials, 3.3% of participants experienced hair loss compared with 1% in the placebo group.
Any hair loss is usually temporary and more likely linked to rapid weight loss than to the weight loss medication specifically. When the body loses weight quickly, it can:
- Release more cortisol — the stress hormone.
- Your body may interpret the weight loss as a form of stress.
- Studies show that higher cortisol levels may slow hair growth.
Diet can also play a role – if you’re eating less, you may not be getting all of the nutrients you need, which can affect hair health.
Pairing weight loss medication with professional support, like Oviva’s programme, helps you build healthy habits and protect your overall wellbeing.
Could retatrutide impact sleep or cause fatigue?
Fatigue has been reported as a side effect of retatrutide. Like other common side effects, this tends to ease over time.
The fatigue may be the result of reduced calorie intake while taking the medication – it may ease as your body adapts.
With the right diet and nutrients, you may be able to manage fatigue more effectively as you adjust your eating habits.
So far, clinical trials have not shown any specific impact on sleep.
What to do if you experience side effects of weight loss medication
Retatrutide isn’t available as a weight loss treatment yet, but medications with similar mechanisms are available, including Wegovy (semaglutide) and Mounjaro (tirzepatide).
If you experience side effects while taking any weight loss medication, speak with your doctor or the healthcare professionals supervising your treatment. They may suggest:
- Lowering the dose or slowing the dosing schedule
- Avoiding foods that may trigger side effects (e.g., fatty foods triggering nausea)
- Managing symptoms through hydration, dietary changes, or injection timing
Who shouldn’t take retatrutide?
Retatrutide hasn’t been licensed for use yet, so the contraindications are unclear. However, like other weight loss injections, it may not be suitable for everyone.
Assuming it follows similar patterns, retatrutide most likely won’t be recommended for people with:
- A history of pancreatitis
- Thyroid cancer or multiple endocrine neoplasia syndrome
- Severe kidney problems
- Severe liver issues
Worried about side effects? You’re not alone, and support is available
Retatrutide isn’t currently available to support weight loss, but if you have a BMI over 35, you may be eligible for Oviva’s NHS-accredited and funded weight loss programme.
With Oviva, you don’t just receive medication — you gain a complete support system designed to help you succeed. This includes:
- 1:1 access to dietitians and health coaches through the Oviva app, so you’re never on your own.
- Tools to stay on track, including meal logging, progress tracking, and practical resources.
- Support for lasting change, helping you build healthy habits that make weight loss sustainable long term.
- Weight loss injections delivered to your door, if appropriate.
Lose weight safely, manage side effects effectively, and feel confident about your long-term health.
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