Risks and side effects – feeling sick and being sick

About this leaflet

This leaflet is about feeling sick (nausea) or being sick (vomiting) after an operation. This is a side effect that you might experience if you have a general anaesthetic. It explains the causes of sickness and what can be done about it. 

General anaesthetics are medicines that give a deep sleep-like state. They are essential for some operations and procedures. During a general anaesthetic, you are unconscious and feel nothing.

You can read about different types of anaesthetics in our Patient information leaflets and video resources section.

What does it feel like?

• You might feel like you are going to be sick (nausea).
• You might be sick (vomit).
• You might retch (trying to be sick but nothing comes up).
• Usually the sensation of sickness lasts an hour or two and stops after treatment. More rarely it can be prolonged and last for more than a day.

How likely is it to happen?

These numbers come from research studies. You can find out about the research we used in our Anaesthesia and risk evidence table.

What causes sickness after a general anaesthetic?

• The drugs used in anaesthesia and some pain relief medicines can make you feel sick. Some regional anaesthetics, such as spinals and epidurals, can also cause sickness.
• Anaesthetics can lower your blood pressure. Low blood pressure can make you feel sick. 
• Fasting (not eating or drinking) before the operation can make you feel sick afterwards, but it is necessary to keep you safe during the anaesthetic. You should follow carefully any instructions you are given about stopping eating and drinking before surgery.
• You are more likely to feel sick if you suffer from travel sickness or have felt sick after anaesthesia before.
• Some operations are more likely to make you feel sick:
  • operations in your abdomen (stomach) or genital area
  • gynaecological (female reproductive system) operations
  • operations in your ‘ear, nose and throat’, such as removing tonsils
  • operations to correct a squint of the eye
  • operations that are more than two or three hours long.
• Anxiety can increase the risk of feeling sick. If you are worried or anxious, tell your anaesthetist. They can talk to you about your worries. Sometimes they can offer medicines to help with anxiety.

The RCoA offers resources to help patients prepare mentally before an operation.

What if I feel sick?

There are things that the team looking after you can do to make you feel better if you feel sick. They will: 

• monitor your blood pressure and heart rate to make sure that your blood pressure is not too low 
• give you fluids and anti-sickness medicines either through a vein or as a tablet to swallow.

What can help prevent sickness?

The type of anaesthetic

Your anaesthetist might use different types of anaesthetics. Some are less likely to make you feel sick. Your anaesthetist will explain which type of anaesthetic is most suitable for you and the type of surgery that you are having. 

Eating and drinking as soon as possible after an operation

You will be advised to stop eating and drinking before your operation. However, going too long without food and drink can make you feel sick after the operation. Try to eat and drink as soon as you are able to after the operation. 

The team looking after you will advise you on when you can start eating and drinking again. They might give you small sips of water soon after the operation and build you up to other drinks and light meals.

What can I do myself?

Act sooner rather than later

Ask your nurses or anaesthetist as soon as you start feeling sick. It is better to treat the feeling of nausea before it gets too bad, because feeling very sick or being sick can affect your recovery. 

Talk to your anaesthetist if you have had an anaesthetic in the past and felt sick afterwards. There are things that they can do to reduce the risk of it happening again.

Do not sit up or get out of bed too quickly after your operation. Your blood pressure can change when you sit up or get up quickly. This can make you feel sick. 

If you are in pain, talk to your anaesthetist or nurses. Severe pain can make you feel sick. They can give you more, or different, pain relief.

Take slow deep breaths if you feel sick. 

You might consider alternative therapies. Acupuncture, acupressure or aromatherapy might help prevent nausea. There is not enough research to say whether these techniques work or how well they work. You will need to arrange a trained professional yourself if you want to try these.

Good to know

Travel sickness 

If you are going home the same day as your operation, you might experience travel sickness. This is because you will be more sensitive to movement.

Disclaimer

We try very hard to keep the information in this leaflet accurate and up-to-date, but we cannot guarantee this. We don’t expect this general information to cover all the questions you might have or to deal with everything that might be important to you. You should discuss your choices and any worries you have with your medical team, using this leaflet as a guide. This leaflet on its own should not be treated as advice. It cannot be used for any commercial or business purpose. For full details, please click here.

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Sixth Edition, November 2024
This leaflet will be reviewed within three years of the date of publication.

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