Having a gastroscopy: what really happens

If you’ve been referred for a gastroscopy, it’s normal to feel nervous. Most people tell us afterwards that it was much quicker and easier than they expected. This guide walks you through what happens before, during and after the test, the choices you’ll have, and what your results mean.

What is a gastroscopy?

A gastroscopy (also called an upper GI endoscopy or OGD) is a test where a thin, flexible tube with a light and camera on the end, called an endoscope, is passed through your mouth and down into your stomach. It lets the team see the lining directly, take small samples (biopsies) and sometimes treat problems at the same time.^[1,4]

It’s used to look for the cause of symptoms such as indigestion, reflux, difficulty swallowing, anaemia or bleeding, and to check on known conditions such as Barrett’s oesophagus.^[1,5]

Why you might need a gastroscopy

Common reasons include:^[1,5]

• indigestion or upper tummy pain that hasn’t settled, or gastritis that needs checking
• reflux that hasn’t responded to treatment, or regular checks for Barrett’s oesophagus
• iron deficiency anaemia, often alongside a colonoscopy
• to take biopsies to confirm coeliac disease
• difficulty swallowing, persistent vomiting, or weight loss
• signs of bleeding from the upper gut

What can a gastroscopy find?

Often the test is normal, which is reassuring and helps rule things out. Common findings include inflammation of the food pipe (oesophagitis), gastritis, a hiatus hernia, ulcers, and signs of coeliac disease. Biopsies can also check for H. pylori. Cancer is an uncommon finding, but a gastroscopy is the best way to find it early.^[1,4]

Before your test

Eating and drinking

Your stomach needs to be empty so the camera can see clearly and the test is safe. Most units ask you to:

• stop eating at least 6 hours before your appointment
• drink only clear fluids, such as water, until about 2 hours before (no milk)

Always follow the instructions in your own appointment letter, as times vary between hospitals.^[1,3]

Your medicines

• Acid-reducing tablets (omeprazole, lansoprazole and similar): some units ask you to stop these for 2 weeks before a first gastroscopy, so that inflammation and H. pylori aren’t hidden. Check your letter.
• Blood thinners (warfarin, apixaban, rivaroxaban, edoxaban, dabigatran, clopidogrel and others): contact the endoscopy unit as soon as you get your appointment. You may need to pause them, or you may not. Don’t stop them on your own.
• Diabetes medicines, especially insulin: you’ll need advice on adjusting doses while you’re fasting. Contact the unit or your diabetes team.
• Weight-loss injections such as semaglutide or tirzepatide slow stomach emptying. Tell the unit you take them, as they may give you different instructions.

These instructions follow NHS patient information. Your own unit’s letter always takes priority.^[2,3]

Keep taking everything else as normal with a sip of water, unless you’re told otherwise.

Throat spray or sedation?

You’ll usually be offered a choice. There’s no right answer: it depends on what matters most to you.

	Throat spray	Sedation
What it is	A local anaesthetic spray that numbs the back of your throat	A medicine given through a small tube in your hand or arm to help you relax
How you’ll feel	Fully awake and alert	Relaxed and drowsy. Many people remember little of the test
Going home	Straight away, and you can drive	You’ll rest for an hour or so, and must be collected
For the next 24 hours	No restrictions, apart from waiting about an hour before eating or drinking	No driving, alcohol, operating machinery or signing important documents, and someone must stay with you
Good for	People who want to get back to normal quickly, or can’t arrange a lift	People who feel very anxious, or have struggled with a previous test

The rules about driving and having someone with you after sedation come from NHS guidance.^[1,2]

Some people choose both. You can talk it through with the nurse on the day.

What happens during the test

1. A nurse checks your details, medicines and allergies, explains the test and asks you to sign a consent form. This is a good time to ask questions.
2. In the procedure room, you lie on your left side. A small plastic mouthguard protects your teeth and the endoscope.
3. You have the throat spray, the sedation, or both. A small clip on your finger monitors your oxygen level.
4. The endoscope is passed over your tongue and you’ll be asked to swallow as it goes down. This is the part most people find hardest, and it only lasts a few seconds.
5. Air is gently blown in to open up your stomach so the lining can be seen. You may feel bloated and burp. That’s normal and fine.
6. Biopsies may be taken. You won’t feel these.
7. The endoscope is removed. The test itself usually takes 5 to 10 minutes.

Transnasal endoscopy: another option in some hospitals

Some units offer transnasal endoscopy (TNE), where a thinner camera is passed through the nose instead of the mouth. It usually needs only a numbing spray for the nose and throat, doesn’t make you gag as much, and you can talk during the test. It isn’t suitable for everyone or every reason for a gastroscopy. Read more in our guide to transnasal endoscopy.^[4]

After the test

• If you had throat spray, wait about an hour before eating or drinking, until your swallow feels normal again.
• A mild sore throat and feeling bloated are common for a few hours.
• If you had sedation, rest at home for the rest of the day, and follow the 24-hour rules above.

Your results

The person who did the test can usually tell you what they saw before you go home, and you’ll get a written report. If you had sedation, bring someone with you to hear the results, as sedation can affect your memory.^[1]

If biopsies were taken, the results usually take a few weeks and will be sent to you or your GP, or discussed at a follow-up appointment. Results are usually much quicker if there’s any concern about cancer.^[3]

Risks

A gastroscopy is a very common and safe test, but no procedure is completely risk-free. Your team will discuss the risks with you before you consent. They include:^[1,2,3]

• a sore throat (common, and settles quickly)
• a reaction to the sedation, such as breathing problems (uncommon, and the team monitors you closely)
• bleeding, usually only if biopsies are taken or treatment is given (rare)
• a tear (perforation) in the food pipe or stomach, which may need surgery (rare: around 1 in 5,000 or fewer for a standard gastroscopy, according to NHS patient information)
• damage to teeth or dental work (rare)

Frequently asked questions

Does a gastroscopy hurt?

It’s usually uncomfortable rather than painful. Most people find the moment of swallowing the camera the hardest part, and it’s over in seconds.

Will I be able to breathe?

Yes. The endoscope goes down your food pipe, not your windpipe, and doesn’t block your breathing. Breathing slowly through your nose helps.

Can I wear dentures?

You’ll be asked to remove them just before the test. Bring a pot to keep them in.

Can I go back to work?

After throat spray only, usually yes. After sedation, plan to take the rest of the day off and the next day too if your work involves driving or safety-critical tasks.

References

1. NHS. Gastroscopy. https://www.nhs.uk/tests-and-treatments/gastroscopy/
2. NHS 111 Wales. Gastroscopy. https://111.wales.nhs.uk/gastroscopy/
3. Sandwell and West Birmingham NHS Trust. Having a gastroscopy (patient leaflet). 2023. https://www.swbh.nhs.uk/wp-content/uploads/2023/12/Having_a_Gastroscopy_ML64581.pdf
4. Beg S, Ragunath K, Wyman A, et al. Quality standards in upper gastrointestinal endoscopy: a position statement of the British Society of Gastroenterology (BSG) and Association of Upper Gastrointestinal Surgeons of Great Britain and Ireland (AUGIS). Gut 2017;66:1886–1899.
5. NICE. Gastro-oesophageal reflux disease and dyspepsia in adults (CG184). https://www.nice.org.uk/guidance/cg184