Semaglutide - Uses, How it Works and Side Effects

How does semaglutide work?  

Semaglutide increases the levels of incretins – hormones – which are naturally produced by the stomach when you eat.   

It works by helping your body to produce more insulin when needed. It also reduces the amount of glucose, or sugar, produced by the liver, and slows down how quickly food is digested. This all helps to lower blood sugar levels and HbA1c.    

Semaglutide can also lead to weight loss. This is because it slows down how quickly food is digested. This means it can help you stay full for longer, which can lead to weight loss. 

How many types of semaglutide are there? 

Semaglutide is available under three different brand names: 

• Ozempic – a type 2 diabetes medication that you inject, which is prescribed to manage blood glucose levels. It should only be prescribed to people with type 2 diabetes.
• Rybelsus – a drug that comes as a tablet that you swallow, which can be used to treat type 2 diabetes.
• Wegovy – a drug that you inject, which is available on the NHS to support weight management.  

  
  Who can take semaglutide? 

  Adults over the age of 18 with type 2 diabetes can take semaglutide. 

  Ozempic and Rybelsus 

  Guidelines from the National Institute for Health and Care Excellence, or NICE for short, recommend that Ozempic and Rybelsus can be prescribed to adults with type 2 diabetes when:

  • Using three medications has not been effective in managing diabetes.
  • Or you have not been able to take the medications. This might be because of side effects or because of other medical conditions.

  Ozempic and Rybelsus are only prescribed when someone has a Body Mass Index, or BMI, of 35kg/m2 or higher, and has additional psychological or other medical conditions that are related to obesity.   

  However, someone with type 2 diabetes can be prescribed Ozempic or Rybelsus if they have a BMI below 35kg/m2 and: 

  • Using insulin would affect their job due to the risk of low blood sugar, also known as hypoglycemia or hypos;
  • Weight loss would lead to improvements in other obesity-related health issues. 

  NICE recommends – due to their risk from obesity-related health problems at a lower BMI – that people from Black African, African-Caribbean, Asian, South Asian, Chinese, and Middle Eastern backgrounds receive Ozempic or Rybelsus at a lower BMI. 

  Wegovy 

  NICE guidelines recommend Wegovy for adults who have a BMI of 30kg/m2 and over, and at least one weight-related health condition, such as prediabetes or type 2 diabetes. 

  
  Who can’t take semaglutide? 

  Some medications might not be suitable for some people, which might be because of medical conditions or other reasons:    

  • Your doctor will tell you to stop taking semaglutide if you develop diabetic ketoacidosis, also called DKA;
  • If you have kidney disease you might not be able to take semaglutide, but this will depend on the stage of your kidney disease;
  • If you have severe liver disease you might not be able to take semaglutide;
  • You might need to temporarily stop semaglutide if you’re going to have an operation;   
  • You should not take semaglutide during pregnancy. It should not be used if you are breastfeeding. If you are planning a pregnancy, it’s very important to speak to a healthcare professional if you are using this medication.    

  When you start a new medication always check with your healthcare team that it’s suitable for you to take. 
  
  

  Semaglutide side effects 

  Common side effects when first starting treatment with semaglutide include: 

  • nausea
  • constipation
  • diarrhoea
  • risk of low blood sugar
  • risk of worsening retinopathy
  • risk of high blood sugar

  Risk of low blood sugar 

  Our pages on the different brands of semaglutide - Ozempic, Wegovy and Rybelsus, have further information about the risk of blood sugar becoming too low when taking these medications.

  Hypos are more likely to happen when you take these drugs with other diabetes medications such as insulin or a sulphonylurea. Speak to your healthcare team if you aren’t sure if the diabetes medication you take increases your risk of hypos.   

  Your healthcare team may advise reducing the dose of your sulphonylurea or insulin medicine when you start taking semaglutide to reduce the risk of hypos. 

  Risk of worsening retinopathy 

  If you have diabetic eye disease, known as diabetic retinopathy, and you’re taking insulin, then your retinopathy could get worse when you start using semaglutide, and this might need treatment.  

  Tell your doctor if you have diabetic eye disease or if you experience eye problems during treatment with semaglutide.   

  Risk of high blood sugar 

  If you take semaglutide with insulin and your insulin dose is reduced too quickly, this can cause high blood sugar, also known as hyperglycaemia, and there is an increased risk of DKA. Your health care team should discuss with you the signs and symptoms of DKA. 

  These are not all the side effects. You will find a full list of known side effects in the Patient Information Leaflet. This comes in the medication box.   

  Like all medications, semaglutide can cause side effects. But when side effects are listed as common in the Patient Information Leaflet, it doesn’t mean that everyone who takes the medication will get them.