Why Do GLP-1 Injections Cause Nausea?

Glucagon-like peptide-1 (GLP-1) receptor agonists like Ozempic, Wegovy and Mounjaro are an effective weight loss tool that can lead to impressive results. But these medications can cause side effects like nausea, vomiting, stomach pain, and other gastrointestinal symptoms.

This family of weight loss injections help you lose weight in three ways.

  1. By acting on the area of the brain responsible for hunger cues

  2. By improving blood glucose regulation

  3. By slowing down gastric emptying (how fast the stomach empties)

It's likely that the way that GLP-1 receptor agonists target the brain and their ability to slow down how quickly the stomach empties both contribute to nausea symptoms.

Usually, you're at an increased risk of experiencing side effects when you first start taking weight loss medication or when your dose is increased. Over time, the body usually adjusts to a higher dose and side effects like nausea or vomiting tend to improve.

How Long Does Nausea Typically Last?

As many as 1 in 10 people taking GLP-1 receptor agonists experience nausea, vomiting, or other gastrointestinal side effects. These symptoms can last for several days and may flair up again when you move up to your next dose. If symptoms proceed for longer than this, it's best to contact your GP.

All side effects are more likely to happen during the first few weeks of starting weight loss treatment as your body gets used to the medication. Everyone's body is different - just because side effects are more common when you start treatment doesn't mean you'll definitely experience them.

Nausea and Related Symptoms

Common Nausea-Related Symptoms from GLP-1 Injections

Alongside feeling sick (nausea) and being sick (vomiting), GLP-1 receptor agonists can also cause:

  • Abdominal discomfort or pain

  • Bloating

  • Loss of appetite

  • Gas

  • Burping

  • Heartburn or acid reflux

  • Diarrhoea

  • Constipation

Some people also experience light-headedness, dizziness, tiredness, weakness, and/or headaches.

Prolonged vomiting or diarrhoea can cause people to lose a lot of fluid and become dehydrated, which may also lead to headaches, dizziness, and tiredness. To avoid this, make sure you're drinking plenty of fluids as dehydration can lead to serious health problems.

When Is Nausea a Sign of Something More Serious?

In rare cases, vomiting and diarrhoea related to weight loss medication can lead to severe dehydration that risks damaging the kidneys.

Severe dehydration needs to be managed in hospital. It's important to make an urgent GP appointment or call 111 if you or someone else is taking a GLP-1 receptor agonist has been vomiting or had diarrhoea and is:

  • Breathing quickly or has a fast heart rate

  • Feeling unusually tired or sleepy

  • Confused or disorientated

  • Peeing less than normal or has very dark urine

  • Dizzy when they stand up for longer than a few seconds

Vomiting may also be a sign of something more serious that's related to medication or another medical problem, such as pancreatitis, low blood sugar, or an allergic reaction.

If you or someone else is experiencing signs of:

  • Pancreatitis - severe, central stomach pain that may come with indigestion, fever, jaundice, stomach swelling, and/or a fast heart beat

  • Low blood sugar - feeling hungry, dizzy, irritable, sweaty, shaky, weak, confused, or feeling your heart beating strangely

  • An allergic reaction- a rash, swelling, skin itching, wheezing, or breathing issues

seek medical advice from your GP, 111, or 999 in an emergency.

The Importance of Consulting a Healthcare Professional

If you experience any side effects after taking a new medication that last longer than a few days, it's best to discuss them with your GP. They'll be able to advise you on whether to continue the medication or not, and whether your symptoms could be caused by an underlying health condition.

In a medical emergency, such as where someone is struggling to breathe, has become confused or unresponsive, has lost consciousness, or is in severe pain, call 999.

For more information about the side effects of the particular medication you're taking, review the patient information leaflet contained in the medication packaging.

Practical Tips to Manage Nausea from GLP-1 Weight Loss Injections

In many cases, nausea or vomiting related to GLP-1 medications gets better by itself with time. There are a few things you can do in the meantime to make things more pleasant.

Adjusting Your Eating Habits

Eat Smaller, More Frequent Meals

Regular smaller meals can help your body get the nutrients it needs without making you feel full and uncomfortable. Try to avoid eating large meals, as these can trigger nausea.

Eat Slowly and Mindfully

Eating food too quickly can trigger bloating and discomfort, which can make things even worse if you're already feeling sick. Take the time to chew every mouthful of food thoroughly before swallowing - this can help slow things down and reduce discomfort.

Incorporate Low-Fat Foods

Fatty, greasy food often makes people feel sick when they eat it, but it can also slow down how quickly the stomach empties, leading to more nausea. Opt for low-fat meals that are high in protein, fruits, and vegetables and try to avoid fried foods or meals high in saturated fat.

Choosing the Right Foods and Drinks

Stay Hydrated with Clear Fluids

Even if you don't feel like eating food, its essential to make sure you're getting enough fluids. Drinking plenty of fluids is even more important if you have vomiting or diarrhoea, as you're losing liquids and can become dehydrated if you don't replace what you've lost.

Water is great, but you can drink any soft drink, hot drink, or soup that you feel like. Clear soups have the added benefit of also providing you with some nutrients. Avoid sugary drinks if you think they may trigger your nausea.

Try Herbal Teas Like Ginger or Peppermint

Ginger and peppermint are natural remedies that may reduce feelings of nausea. Drinking peppermint or ginger tea helps you stay hydrated while naturally working to make you feel less sick.

Keeping a Food Diary

Certain foods may be triggering or worsening your symptoms without you realising. A food diary can help with this. Write down what you eat in a day along with any nausea, vomiting, or other gastrointestinal symptoms you experience. That way, it'll be easier to identify if any foods or drinks are making your symptoms worse.

Lifestyle Changes to Reduce Nausea

Get Fresh Air and Gentle Exercise

Some people find that going outside and getting a bit of fresh air helps with their nausea, although we don't know precisely why. It may be helpful to stretch your legs and take a walk or other type of gentle exercise, but be careful not to over exert yourself.

Resting in an Elevated Position

Laying down flat can increase acid reflux symptoms and may lead you to experience nausea. Avoid laying flat after meals especially, as this can make these symptoms worse.

Can Over-the-counter Medications Help?

Over the counter medications are available and can help to relieve mild nausea symptoms. You can discuss the different options with a pharmacist and they can advise you which products may be suitable for your symptoms.

Avoid self-medicating without seeking help from a professional. A healthcare provider can check whether medicines are suitable for you, determine whether your symptoms are caused by something more serious, and may even consider changing your weight loss medication if your symptoms are severe.

When Might a Doctor Adjust Your Medication?

If your symptoms continue for a long time, if they're really affecting your daily life, or your health is at risk, your healthcare provider may suggest adjusting your dose or stopping the medication altogether.

All dose adjustments should be discussed with your healthcare provider - never change your dose unless advised to do so by a healthcare professional.

Other Medications That May Affect Nausea

It's not just GLP-1 agonists that cause nausea. Many other prescription and non-prescription medications can cause nausea and vomiting as side effects, and these side effects may be worse when they're taken alongside weight loss medication.

Before starting a GLP-1 agonist or if you're suffering from side effects, you should discuss all your current medications with a healthcare professional. This will help them ensure it's safe for you take your current medication safely with weight loss injections.

Factors That Can Make Nausea Worse

Higher Doses and Rapid Dose Increases

Side effects like nausea and vomiting are more common after a dose increase. Increasing doses too quickly doesn't give your body enough time to adjust to the medication, which can lead to side effects.

By following the dosing schedule for your weight loss drug, you can gradually increase up to the maintenance dose at a speed that allows your body to adjust. Schedules vary between different drugs and your healthcare provider can go into the specifics for the medication you're taking.

Other Health Conditions That Can Contribute

If you already have underlying health problems that affect your digestive system, this may increase the likelihood of experiencing weight loss medication side effects like nausea and vomiting.

Some people are more at risk of becoming dehydrated or seriously unwell if they experience nausea and vomiting over several days, such as people with kidney problems or older people. If you know you have an underlying health condition and become unwell, it's even more important for you to seek medical advice early so you can avoid things getting worse.

Summary: Managing Nausea on Your Weight Loss Journey

Experiencing side effects like nausea or vomiting when taking GLP-1 agonists can be frustrating, but usually these symptoms improve once your body gets used to the medication.

Most of the time, nausea and vomiting can be managed at home by eating plain foods, staying hydrated, and not overexerting yourself. If symptoms continue for more than a few days or are severe, seek medical advice.

FAQs

How long will the nausea last when starting GLP-1 injections?

Nausea and other side effects typically last for a few days after starting GLP-1 injections or after a dose increase. If symptoms continue for longer than this or you become seriously unwell, seek medical attention.

Are there specific foods I should avoid while using weight loss injections?

Weight loss injects don't interact with particular foods, but high-fat, calorie-dense, and ultra-processed foods may counteract your weight loss efforts. Rich, fatty, or acidic foods can also make side effects worse so may be best to avoid.

Is it safe to continue my injections if I feel nauseous?

Yes, as long as you're eating and drink plenty of water, it's usually safe for you to continue your medication if you feel nauseous. If your symptoms get worse or continue for more than a few days, you should talk to your healthcare provider.

Can nausea indicate a serious problem like thyroid cancer or pancreatitis?

In some cases, nausea may be an indicator of something more serious, however it's unlikely to be the only symptom. Nausea and vomiting are common side effects of weight loss injections, affecting up to 1 in 10 people who take the medications, and serious side effects are much rarer.

However, if you're worried about your symptoms and think it could be something more serious, it's best to seek medical advice.

What should I do if my nausea gets worse after increasing my dose?

Usually the nausea will improve again after a few days as your body adjusts to the dose increase. In the meantime, it may help to eat smaller meals of plain foods and try natural remedies like ginger or peppermint tea. If symptoms continue for a week or more, you may want to talk to a healthcare professional.

Can herbal remedies like ginger really help with nausea?

Some studies have found that ginger and peppermint can naturally reduce symptoms of nausea, and many people find that these natural remedies offer relief from mild nausea.

When should I seek emergency medical care for nausea?

Nausea itself isn't usually a reason to seek emergency medical care, however ongoing vomiting or diarrhoea can be if it leads to dehydration or you're unable to keep any food or drink down over several days.

If nausea is accompanied by severe pain, fever, jaundice, confusion, loss of consciousness, or any other concerning symptoms, seek medical advice by calling 111 or 999 in an emergency.


Written by

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Aliysha Parveen

Pharmacist Independent Prescriber

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