weight loss injections side effects


Weight loss injections are growing in popularity as a treatment for obesity, and results show that they’re effective, with most patients losing over 5% of their initial starting weight within 12 weeks of treatment. However, it can be easy to forget that they’re prescription medicines and can cause side effects that might not be pleasant.

Side effects are symptoms that are caused by taking certain medications, but it’s important to know that not everybody experiences them. Everyone’s bodies react differently to medicines, but it’s still important to be prepared and know about the side effects of weight loss injections so that you know how to deal with them if you do experience any. However, if the side effects prove too much to handle and they start to outweigh the benefits of the injections, you should talk to your doctor about stopping treatment and look at the alternatives that might be available to you.


Most common weight loss injections side effects

Some of the most common weight loss injections side effects that you might experience when starting treatment include:

  • Nausea
  • Diarrhoea
  • Vomiting
  • Low blood sugar (hypoglycaemia)
  • Indigestion
  • Gastritis
  • Reflux/heartburn
  • Stomach pain
  • Bloating
  • Constipation
  • Burping
  • Gall stones
  • Dizziness
  • Tiredness
  • Flatulence
  • Changes in taste
  • Fast pulse
  • Injection site reactions

Common side effects mean that during clinical trials, a significant amount of patients experienced these symptoms. Side effects can vary wildly with different medicines due to the way that they work in your body, but these symptoms were found to be most common for those taking weight loss injections.

However, there’s still a chance that you could experience other side effects that aren’t listed here or in the patient information leaflet for your injections. If you do notice any changes after you start taking the medication, you can report a new side effect via the MHRA yellow card scheme, which is available as an app on both iOS and android operating systems.

So now that you know the most common symptoms that you might feel, how do you deal with them in order to feel as good as possible whilst using weight loss injections?


Dealing with common weight loss injections side effects

Luckily, some of the side effects do tend to disappear within a couple of weeks of starting treatment, so if you do suffer from them, you shouldn’t have to worry about it for too long, although it’s still a good idea to know how to combat certain symptoms so you can be as comfortable as possible:


Nausea & vomiting:

Nausea is one of the symptoms that tend to get better and even disappear once your body adjusts to the weight loss injections, but it can be one of the most debilitating side effects, especially if you’re feeling or being sick frequently.

Many people find it useful to distract themselves and think about other things rather than focusing on the fact that they feel queasy. There are various ways to distract yourself, such as listening to music, colouring, watching TV, or carrying on with some work that you need to do if you feel up to it.

Eating or drinking products that contain ginger might be another good way to combat nausea and vomiting, as the spice contains chemicals that are thought to work in the digestive system to relieve these symptoms. Many people find that ginger biscuits or cordials work well at keeping nausea at bay. However, if you don’t feel able to eat, it’s important not to force yourself as this could make nausea even worse.

When you do feel that you can stomach some food again, you should eat small amounts of bland foods, avoiding anything spicy, fatty, or greasy.  You may also find that it helps to wear comfortable, loose-fitting clothes that don’t squeeze the stomach.

If these home remedies fail to make you feel any better, you can ask your local pharmacist or GP about anti-emetic medicines. These type of drugs help to relieve nausea, and some may even be available over the counter at most pharmacies.

Above all else, it’s important to stay hydrated even if you don’t feel like eating anything. You should take small sips of water rather than big gulps as this may upset the stomach and make you feel worse. Always see your doctor if you’ve been vomiting for more than 2 days despite trying to combat your nausea.

ginger for nausea



Low blood sugar (hypoglycaemia):

Because the same drug in weight loss injections is also used to regulate blood glucose levels in those with diabetes, there’s a chance that you might experience hypoglycaemia if your blood sugar is usually within a normal, healthy range.

If you experience a number of the following symptoms, it’s possible that your blood sugar is too low:

  • Feeling hungry
  • Sweating
  • Tingling lips
  • Shakiness or trembling
  • Dizziness
  • Feeling tired
  • Fast or pounding heartbeat
  • Irritability
  • Turning pale
  • Blurred vision
  • Difficulty concentrating
  • Confusion

If you think you may be suffering from hypoglycaemia, it’s important to treat it as quickly as possible to avoid it getting worse or becoming dangerous.

Usually, the most effective way to treat low blood sugar is to have something sugary, either a drink or a snack such as full-sugar soft drinks or a few sweets. However, if you find that this happens often, it may be a good idea to carry some glucose or dextrose tablets on you at all times for quick and easy treatment. You may be able to find dextrose tablets in your local pharmacy. You should start to feel better within 10-15 minutes, and if you have access to a blood glucose monitor, it may be a good idea to check your blood sugar levels after this amount of time has passed. If you still feel unwell, you should have some more sugar.

Despite the fact that weight loss injections reduce your appetite, it’s still important to eat at regular intervals, though you don’t need to eat a meal if you don’t feel like it. Even a piece of fruit can be enough to stop your blood sugar levels from dropping.

The key to treating hypoglycaemia and recovering from it quickly is to notice the symptoms early enough, so it’s important to familiarise yourself with them in order to help yourself as soon as possible.



Diarrhoea is another side effect of weight loss injections that should disappear once your body is used to the new drug. However, untreated diarrhoea can be unpleasant, frustrating, and even painful, so it’s always a good idea to try to treat it as soon as it starts.

One of the most important things to remember when suffering from diarrhoea is to stay hydrated. You can lose a lot of fluid with watery stools, and dehydration can cause a whole host of other problems. However, you should avoid fizzy drinks and fruit juices wherever possible as these can actually make diarrhoea worse. It’s a good idea to stick to water, or you can add sugar-free cordials for flavour. Alternatively, you can use rehydration sachets such as dioralyte to replace salts and minerals that might have been lost through watery stools. This is especially important if you have frequent loose or watery bowel movements.

In terms of medication, one of the fastest and most effective ways to combat diarrhoea is to take loperamide – a medicine that’s available in supermarkets, pharmacies, or even from your doctor for larger quantities. It’s common to take two 2mg loperamide tablets or capsules to start with, and then one tablet or capsule after each loose bowel movement. Loperamide generally starts to take effect within half an hour of taking it and can make your stools firmer as well as reducing the number of times that you need to visit the toilet. Loperamide treats diarrhoea, but not the cause (in this case, weight loss injections), however, it might not be suitable for some people, for example, those with an inflammatory bowel condition.

If your diarrhoea lasts for more than two days, you should speak to a healthcare professional for advice and rule out any other causes.

loperamide for diarrhoea

Gastritis and stomach pain: 

Gastritis is a medical term for inflammation of the lining of the stomach. It can be painful and frustrating, causing symptoms such as:

  • Indigestion
  • Gnawing stomach pain
  • Nausea
  • Vomiting
  • Feeling full after eating

However, as many of these symptoms are side effects of weight loss injections themselves, it can be difficult to tell whether you’re suffering from gastritis or not.

As a general rule when it comes to stomach pain, it’s important to avoid taking NSAIDs such as ibuprofen or naproxen, as these can irritate the stomach even further and make the pain and inflammation worse.

Antacids can also be used to relieve some of the symptoms of gastritis, but be careful not to use any non-prescription medicines for longer than advised without seeing your doctor for advice.

Gastritis and stomach pain do usually subside on their own in time, but if you need to take pain relief, paracetamol is the safest option as it isn’t known to irritate the stomach or cause any gastrointestinal problems. It’s also a good idea to avoid spicy or rich foods as these can also irritate the lining of the stomach.


Bloating, flatulence and burping:

These side effects are usually caused by excess air in your stomach or intestines and can be quite uncomfortable as well as embarrassing. Luckily, there are things that you can do at home to reduce the symptoms, such as cutting down on certain foods that cause excess wind such as beans, sprouts and cabbage etc. You may even know that some other foods trigger you to feel bloated, so it may be a good idea to avoid these whilst you’re suffering.

You should also avoid fizzy drinks and chewing gum wherever possible, as these can contribute to excess air in the stomach and intestines, causing more bloating, flatulence and burping, but still, drinks such as water and cordials are a safe option to keep you hydrated.

There are also remedies for bloating and trapped wind that is available to buy in supermarkets and pharmacies, for example, wind-eze and Andrew’s salts. It may be worth trying these if you feel really uncomfortable or home remedies aren’t helping. However, it’s important to remember that bloating may be a sign of constipation, so it’s worth keeping your eye out for any changes in bowel habits.


Indigestion, reflux, and heartburn:

These side effects can cause chest pain and burning, making you feel quite unwell at times. However, there are some ways to combat it and to prevent them from happening in the first place.

One of the key pieces of advice to avoid indigestion, reflux and heartburn when taking weight loss injections is to eat smaller portions. You can always add more to your plate afterwards if you still feel hungry, but many people find that they’re satisfied after eating smaller amounts.

You shouldn’t eat around bedtime, as lying down whilst your stomach is trying to digest food can aggravate the symptoms and make them much worse. In fact, many people find that it helps to have their head slightly raised when they’re in bed, sleeping in a reclined position instead of being lay flat. This discourages any stomach acid from making its way up the oesophagus.

If these symptoms persist, you should see your GP, as you may be at risk of developing GORD – gastro-oesophageal reflux disease. They may suggest to you that you start taking an antacid medicine such as omeprazole or lansoprazole in order to reduce the amount of acid that your stomach produces, and in turn, this should relieve the symptoms. Other medicines such as ranitidine and some strengths of esomeprazole are available in supermarkets or pharmacies if you only suffer from heartburn occasionally and want fast relief.

weight loss injections side effects



Constipation is usually caused by your stools being too dry, making them harder to pass. When you’re constipated, it’s important to drink plenty of fluids in order to hydrate your stools. You should also increase your fibre intake to encourage softer stools. Constipation can cause other problems such as haemorrhoids or anal fissures through straining, so it’s important to try and treat the problem as soon as you notice it.

If you find that increasing your fluid and fibre intake isn’t helping, there are several types of laxatives that might help, some of which are available in supermarkets or over the counter in pharmacies. The main four types of laxatives include:

  • Bulk-forming laxatives
  • Osmotic laxatives
  • Stimulants
  • Poo-softeners

One of the most popular and effective laxatives is Senna, which can be bought easily. It usually works within 6-12 hours and is great for fast relief of short-term constipation. If you can’t take Senna, or if it doesn’t help to relieve your constipation, talk to your local pharmacist for advice.

Don’t take laxatives if you aren’t constipated. It won’t speed up weight loss and can be dangerous, putting you at risk of dehydration.


Gall stones:

Gall stones themselves don’t usually cause any symptoms unless they’re blocking the bile duct and causing problems. They’re hard lumps that are usually made up of cholesterol, and are found in the gallbladder.

You may have gall stones that are causing problems if you experience any of the following:

    • Sudden and severe abdominal pain
    • Excessive sweating
    • Nausea
    • Vomiting
    • Temperature of 38 or above
    • Rapid heartbeat
    • Itchy skin
    • Diarrhoea
    • Chills
    • Confusion
    • Loss of appetite

If you think you may be suffering from gall stones, you really should make an appointment to see your doctor. Whilst treatment isn’t always necessary, they might be able to prescribe medication for you based on your symptoms, or even refer you for surgery if they feel as though you need it.



Whilst it's a common feeling, dizziness can leave us feeling sick and unwell. It can be caused by dehydration, low blood sugar, not eating enough, or any other number of reasons. The main way to combat dizziness is to avoid making fast movements as this can make it much worse. Keep yourself well hydrated with water if you suspect that it may be due to dehydration, and stay aware of the symptoms of hypoglycaemia in case you need a sugar boost. Travel sickness tablets may help with nausea brought about by dizziness, and most of these are available over the counter in pharmacies. If you’re at home, it may help to lie in a semi-reclined position and to close your eyes to stop any spinning sensations you might feel.



Tiredness is something we all feel, but when you’re taking a new medicine such as weight loss injections, it can seem more extreme than normal whilst your body adjusts.

It’s important to make sure that you’re getting enough sleep through the night – usually around 8-9 hours, but if you’re still tired after this, you may need medical help to stay or feel more awake.

Tiredness can be caused by low energy or even low blood sugar levels, so it’s important to make sure that you’re eating enough for your body to function, even if you aren’t eating a full meal every 4 hours. Small but healthy snacks are often the best way to stay satisfied whilst keeping awake.

If your fatigue is getting in the way of daily life and you’re struggling with work, you should make an appointment with your doctor to discuss medicines that might be suitable for you. Modafinil is a drug that’s usually prescribed to people with narcolepsy – a condition that causes excessive sleepiness. If your doctor thinks it may help with short-term tiredness that’s affecting the rest of your life, they may prescribe it to you to help you feel more awake.

modafinil for tiredness


Injection site reactions:

Injection site reactions are common with these types of medicines. If it’s your first time using subcutaneous injections, it’s always a good idea to ask a pharmacist or practice nurse to show you how to do it properly and minimise the risk of reaction.

It’s also important to keep changing the spot where you inject to avoid damage to that area. It might be helpful to keep a note of where you most recently injected so you can choose a different spot next time.

If you have an allergic skin reaction to the weight loss injections, you should seek medical help by calling 111 (or 999 if you’re showing signs of severe allergic reaction or anaphylaxis). You may need to stop taking the injections if this happens.