GLP-1 medications are weight loss treatments that can be used by some people with obesity and overweight. They work by suppressing appetite – increasing feelings of fullness after eating, slowing down digestion, reducing feelings of hunger and cravings, and helping manage blood sugars – to allow people to focus on improving their diet. Like all medicines, GLP-1 medications can have some side effects. In this article, we’ll take a closer look at some of these.
Side effects of GLP-1 medications
GLP-1 medications are effective and ‘acceptably safe’ when used as directed … but what does this mean?
GLP-1 medications do have side effects, but when you compare these to how effective they are in helping people lose weight, for most people, the benefits are greater than the risks.
As you might expect, many of the side effects are linked to how the medications work, so they affect parts of the digestive system or blood sugar levels. Some of the side effects are related to the levels of weight loss that people have while taking medicines.
The most common side effects are not serious, but people can experience serious side effects that require urgent medical attention, so it’s important to be aware of those.
We won’t talk about every possible side effect here– if you are taking a GLP-1 medication, you should read the information leaflet to get the full details.
If you are taking a GLP-1 medication, and you experience a side effect that you are concerned about, gets worse or does not get better, you should seek medical advice.
Side effects of the digestive system
GLP-1 medications can lead to side effects affecting the digestive system in more than 1 in 10 people who take them. These side effects include nausea, vomiting, diarrhoea and constipation. These usually happen when starting treatment or when increasing the dose, and typically resolve over time.
One way to reduce these side effects is to start with a low dose and increase it gradually, as needed – and this should be done for everyone taking these treatments. If someone is struggling to manage digestive side effects, then the dose should not be increased.
If there is vomiting or diarrhoea, then dehydration could also become an issue, so it is important to stay hydrated.
How can you manage digestive side effects?
What helps you feel better will depend on the symptoms you have and will be different for everyone. You could try:
- Eating smaller meals, slowly, to avoid the stomach becoming too full
- Chewing each mouthful well to help the digestive system and reduce reflux
- Drinking plenty of fluids to help with digestion, as well as preventing dehydration, fatigue and headaches
- Avoiding fatty foods – as high-fat foods take longer to digest, they may add to nausea
- Avoiding high fibre foods – although fibre can help with constipation, too much can worsen nausea, vomiting or diarrhoea, especially if it is increased quickly
- Ginger or peppermint tea, to help with nausea
- Medications to address specific symptoms
If you make changes to your diet to help manage digestive side effects, try to focus on eating healthy, nutritious foods. If you are part of the Genwell weight care programme, your wellbeing coach can help you develop a personalised plan.
Effect of GLP-1s on blood sugars
GLP-1 medications can be used to help manage blood sugar levels in people with type 2 diabetes.
When blood sugar is raised, such as after eating, GLP-1 medications increase insulin production – and they increase insulin sensitivity – so blood sugar levels are reduced. When insulin and blood sugar levels are not well controlled, this can lead to fat being stored in the body, so controlling these can help aid weight loss.
Sometimes, GLP-1 medications can reduce blood sugar to low levels – called hypoglycaemia. This can be more common in people with diabetes who are using other diabetic medications, but it can also happen in people without diabetes.
Signs of low blood sugar include feeling hungry, dizzy, anxious, sweating, shaking, confusion and blurred vision. If you think you have low blood sugar, you should seek urgent medical advice.
Hair loss – a side effect of GLP-1 medications or a side effect of weight loss?
Hair loss is listed as a common side effect, meaning it affects between 1 in 10 and 1 in 100 people taking GLP-1 medications. The hair loss is usually mild and temporary.
The exact reason for hair loss is not fully understood yet, but it could be due to weight loss, rather than the medication itself. When someone loses a lot of weight quickly, the body can respond by shedding hair.
Hair loss could also be linked to changes in the diet that do not deliver enough nutrients to the body.
How can you manage hair loss side effects?
To try to prevent hair loss, you should ideally aim to:
- Lose weight gradually; this is always the healthiest way to lose weight
- Eat a healthy, nutritious diet focusing on eating enough protein and including the micronutrients the body needs for healthy hair growth, such as iron, zinc and omega-3 fatty acids
You could also consider adding a vitamin supplement, if needed.
Effect of weight loss on skin
Although not a side effect of GLP-1 medications as such, rapid or significant weight loss can lead to concerns about the appearance of the skin. There are two main areas of concern: ageing of the face – sometimes termed “Ozempic Face” on social media – and excess skin on the body.
- “Ozempic Face” typically describes someone with sunken eyes, hollow cheeks and sagging skin, resulting in jowls. This is due to the rapid loss of fat from the face, and this can be more pronounced in older people who have naturally lower levels of collagen. However, this explanation might be too simplistic because some also suggest that GLP-1 medications may affect skin elasticity and repair, and that nutrient deficiencies during weight loss might also have a part to play
- Whenever someone loses a lot of weight, there is the risk of excess skin on the body. This happens when the fat and structural proteins that support the skin are lost, and it starts to sag
How can you manage skin changes?
To manage these changes, you can try to:
- Lose weight gradually to give skin time to adjust
- Stay hydrated to keep the skin supple
- Eat a nutritious diet to support healthy muscles and skin
- Introduce regular strength training to help maintain muscle mass
- Use moisturisers or other specialist skin products
- If you think surgery is needed, speak to a healthcare professional for advice
Seeing changes to your skin can be emotional. If you are part of the Genwell care programme, speak to your wellbeing coach for further support.
When to seek urgent medical advice
There are times when having a side effect means you should seek urgent medical advice. These include:
- Severe pain in your stomach or back that does not go away. This could be a sign of a more serious condition affecting the pancreas
- An allergic reaction to the injection, e.g., swelling of the face, lips or tongue, difficulty breathing or swallowing
- Severe or persistent vomiting
- Severe dehydration (very dark urine, dizziness, fainting)
- A sudden change in your eyesight
- Signs of low blood sugar (e.g., dizziness, shaking, sweating)
If you experience any of these side effects, seek urgent medical assistance through your health care provider, 111 (or 999 if there is a severe allergic reaction) or attend an accident and emergency.
Key messages
- The side effects of GLP-1 medications are usually manageable with adjustments to medication, diet and hydration
- Side effects of the digestive system (e.g., nausea, vomiting, diarrhoea, and constipation) are common, especially when first starting treatment or increasing the dose, but usually improve over time
- Some side effects, such as hair loss and face changes, may be related to weight loss rather than GLP-1 medications specifically – a gradual approach to weight loss is always recommended
- Serious side effects, although not common, can happen, and urgent medical advice should be sought. These include signs of low blood sugar, dehydration or allergic reactions, severe stomach or back pain, severe or persistent vomiting and eyesight changes
What our clinical experts say
Starting GLP-1s can be daunting, particularly when we know serious side effects, although rare, can occur. However, obesity and weight-related conditions can also have a significant impact on our long-term health and lifespan. Being aware of both the risks and benefits is essential so you can make a decision about the best treatment option for you. The good news is that most side effects are mild, manageable and transient. At Genwell, our doctors and wellbeing coaches are here to support you if you encounter any side effects and work with you to manage and minimise them.
Dr Caroline Butler
Genwell reflections
Side effects of GLP-1 medications, or of weight loss, can be concerning, but there are steps you can take to manage these.
If you are part of the Genwell care programme, support is always available – you don’t have to decide alone what’s “serious enough” to ask about.
Your doctor or wellbeing coach will be able to provide advice on lifestyle changes, medications, diet, nutrition and more.
At Genwell, we support a healthy approach to weight loss, helping you find a way that works for you.