Colonoscopy & Screening

01 October 2026

Is Colonoscopy Painful? What to Expect Before, During, and After

Medically reviewed by Dr Sim Hsien Lin, Colorectal & General Surgeon at Sincere Surgery Centre. Information is accurate at the time of publication and will be reviewed periodically.
Date: 1 October 2026

Introduction

It is common to feel concerned about discomfort before a colonoscopy. The procedure involves passing a flexible camera through the anus to examine the lining of the colon and rectum, so patients often want to know what they will feel and how the procedure is managed.

A colonoscopy may cause some pressure, bloating or discomfort. Sedation may be used to help patients relax, depending on the individual and the planned procedure. HealthHub Singapore notes that colonoscopy may cause some discomfort and may be performed with sedation, which your doctor will discuss with you beforehand. ^[R1]

This guide explains what to expect before, during and after a colonoscopy, including bowel preparation, sedation, possible sensations during the procedure and recovery afterwards.

Why Is a Colonoscopy Performed?

A colonoscopy allows the doctor to examine the inner lining of the large intestine, including the colon and rectum.

It may be used:

To investigate symptoms such as rectal bleeding
To assess persistent changes in bowel habits
To investigate unexplained abdominal symptoms
To follow up an abnormal screening result
For colorectal cancer screening in appropriate patients
To identify and remove certain colon polyps
To obtain tissue samples when needed

During colonoscopy, polyps can often be removed and abnormal tissue can be biopsied. Removing certain polyps may reduce the risk of them progressing to colorectal cancer. ^[R2]

In Singapore, colorectal cancer screening for average-risk individuals is recommended from age 50. FIT is recommended annually, while colonoscopy may be used as a screening option or recommended based on a person’s risk profile. ^[^R3^,^R4^]

Before the Colonoscopy: Preparing for the Procedure

Good bowel preparation is important because stool remaining in the colon can prevent the doctor from assessing the bowel lining clearly. ^[^R2^,^R5^]

Your healthcare team will provide specific instructions based on the bowel preparation prescribed to you.

Discuss Your Medical History and Medicines

Before the procedure, tell your doctor about:

Your medical conditions
Previous reactions to sedation or anaesthesia
Drug allergies
Prescription medicines
Over-the-counter medicines
Vitamins and supplements
Blood-thinning medication
Diabetes medication
Iron supplements

Some medicines or supplements may need to be adjusted before colonoscopy, but do not stop prescribed medication on your own. Follow the instructions given by your doctor or clinical team. ^[^R2^,^R5^]

This is particularly important for blood thinners, diabetes medication and iron products, as the instructions may differ depending on your health and the type of procedure planned. ^[^R5^]

Follow the Dietary Instructions Provided

Patients are usually given dietary instructions before colonoscopy.
Depending on the bowel-preparation protocol, this may involve:

Omitting certain high-fibre foods before the procedure
Following a clear-liquid diet for a period before colonoscopy
Avoiding certain coloured drinks or foods
Stopping food and fluids at the instructed time

Your exact diet and fasting instructions may vary, so follow the written instructions provided by your healthcare team rather than relying on general online advice. ^[^R2^,^R5^]

Complete the Bowel Preparation

The medication causes frequent loose or watery bowel movements. A well-prepared bowel allows the doctor to inspect the colon lining more clearly and reduces the chance that small abnormalities are obscured by residual stool. ^[^R5^]

Some bowel-preparation regimens use a split dose, with part of the preparation taken the evening before and the remaining portion closer to the procedure. The exact timing depends on your prescribed regimen. ^[^R5^]

By the end of the preparation, the output is generally expected to become watery and relatively clear.

If you cannot complete the preparation, are vomiting repeatedly or are unsure whether the bowel preparation has worked adequately, contact your healthcare team for advice rather than changing the regimen yourself.

During the Colonoscopy: What Happens?

Preparation and Sedation

Before the procedure, you may be asked to change into a gown and an intravenous line may be inserted.

Sedation may be offered to help you relax and improve tolerance of the procedure. The appropriate type and level of sedation depend on your medical condition, preferences and the planned procedure. ^[R1^,^R6]

During sedated endoscopy, clinical staff monitor your condition, including vital signs such as heart rate, blood pressure and oxygen levels.^[^R6]

How the Colonoscope Is Used

During the procedure, you will usually lie on your side.
The doctor gently inserts a flexible colonoscope through the anus and advances it through the rectum and colon. The camera at the end of the scope allows the doctor to inspect the bowel lining.

Air or carbon dioxide may be introduced to inflate the colon so that the lining can be seen more clearly. This can contribute to pressure, bloating or cramping in some patients.
HealthHub states that insertion of the colonoscope may cause some discomfort, while sedation may be used to help patients relax. ^[R1 ^]

Will I Feel Pain During a Colonoscopy?

The experience varies from person to person.

Some patients may feel:

Pressure
Bloating
Cramping
An urge to pass gas
Brief discomfort as the scope moves through the bowel

Sedation can reduce anxiety and discomfort, but it is better not to promise that every patient will be completely pain-free.

If you are worried about discomfort, discuss the available sedation options with your doctor before the procedure.

What Happens If a Polyp Is Found?

If a polyp is identified, the doctor may be able to remove it during the same colonoscopy.

Polyps are tissue growths in the colon. Most are not cancerous, but some types can develop into cancer over time. Removing appropriate polyps can therefore help reduce colorectal cancer risk. ^[^R2^]

If abnormal tissue is found, a biopsy may also be taken and sent for laboratory examination. Patients generally do not feel the removal of a polyp or biopsy itself. ^[^R2^]

How Long Does a Colonoscopy Take?

HealthHub Singapore states that a screening colonoscopy generally takes around 20 to 30 minutes. ^[^R3^]

The total appointment will be longer because time is also needed for:

Registration and preparation
Sedation, if used
The procedure itself
Recovery and observation afterwards

The actual duration may vary depending on what is found and whether additional procedures such as biopsy or polyp removal are required.

After the Colonoscopy: What to Expect During Recovery

Recovery After Sedation

After the procedure, you will rest while the effects of sedation begin to wear off.

NIDDK notes that patients are commonly observed for around 30 to 60 minutes after colonoscopy, although recovery time may vary. ^[^R2^]

If you received sedation, arrange for someone to accompany you home.

HealthHub advises that it is unsafe to drive or travel home alone after sedation, while NIDDK similarly recommends arranging transport because sedative effects take time to wear off. ^[R1^,^R2]

Follow the discharge instructions given by your healthcare team regarding driving, work, important decisions and other activities after sedation.

Bloating and Mild Cramping

It is common to experience some bloating or abdominal cramping after colonoscopy because air or gas is introduced into the bowel during the examination.Walking gently and passing gas may help relieve this discomfort.

NIDDK notes that bloating or cramping may occur during the first hour after colonoscopy, and many patients return to their usual diet by the following day unless their doctor advises otherwise. ^[^R2^]

Eating and Taking Medication Afterwards

Your healthcare team will advise when you may resume eating and drinking.

Many patients can gradually return to their usual diet after the procedure, although individual instructions may differ depending on sedation, biopsy, polyp removal or other factors.

Ask your doctor when to restart medicines that were stopped or adjusted before the procedure, particularly blood-thinning medication.

When Should You Seek Medical Attention After Colonoscopy?

A small amount of rectal bleeding may occur after a biopsy or polyp removal. ^[^R2^]
However, seek medical attention promptly if you experience symptoms such as:

Heavy or persistent rectal bleeding
Severe or worsening abdominal pain
Fever
Persistent vomiting
Severe dizziness or fainting
Difficulty breathing
Other symptoms that concern you after the procedure

Although complications are uncommon, recognised risks of colonoscopy include bleeding, perforation of the colon and reactions related to sedation. ^[^R2^]

Follow the emergency and aftercare instructions provided by your clinical team.

Colonoscopy for Colorectal Cancer Screening in Singapore

For people at average risk and without symptoms, Singapore's current colorectal cancer screening recommendation begins at age 50. ^[^R3^,^R7^]

FIT is recommended annually for average-risk individuals. Colonoscopy is another screening option, with the appropriate interval depending on the person’s risk profile and previous findings. HealthHub lists an interval of approximately 5 to 10 years for average-risk individuals undergoing colonoscopy. ^[^R3^]

People with higher-risk factors—such as certain family histories or a personal history of colorectal polyps—may be advised to begin colonoscopy earlier or undergo it more frequently. ^[^R3^]

If you already have symptoms such as blood in the stool or persistent changes in bowel habits, this is different from routine screening. You should discuss the symptoms with a doctor rather than waiting for your next screening date. ^[^R3^,^R7^]

You can learn more about SSC’s colorectal cancer screening and treatment services.

Conclusion

Concern about discomfort is a common reason patients feel anxious about colonoscopy. The procedure can cause pressure, bloating or cramping, but sedation may be used to improve comfort and help patients relax. The experience varies between individuals, and your doctor can discuss what type of sedation and preparation is appropriate for you.

Good bowel preparation is an important part of a successful examination, and following the instructions provided by your clinical team helps the doctor obtain a clearer view of the colon.
If you have been advised to undergo colonoscopy or are unsure whether the procedure is appropriate for your symptoms or screening needs, a medical consultation can help clarify the next step.

Frequently Asked Questions

Is colonoscopy painful?

Some patients experience pressure, bloating, cramping or discomfort during colonoscopy. Sedation may be offered to help you relax and improve tolerance of the procedure. ^[R1^,^R6]

Individual experience varies, so discuss any concerns about pain or sedation with your doctor beforehand.

How long does a colonoscopy take?

A screening colonoscopy generally takes approximately 20 to 30 minutes, according to HealthHub Singapore. ^[^R3^]

Additional time is needed for preparation and recovery, particularly if sedation is used.

What should I expect during the appointment?

Your appointment may involve registration, preparation, sedation if appropriate, the colonoscopy itself and a recovery period afterwards.

The total duration varies between patients and depends on whether biopsy or polyp removal is performed.

How long does it take to get colonoscopy results?

Your doctor may be able to discuss the visual findings after you have recovered sufficiently from sedation.

If tissue or a polyp is sent to a laboratory, the result will take additional time. NIDDK notes that pathology results may take several days or longer. ^[^R2^]

Your clinical team will advise when and how your results will be reviewed.

Is it normal to see blood after a colonoscopy?

A small amount of rectal bleeding may occur after a biopsy or polyp removal. ^[^R2^]

Seek medical advice if the bleeding is heavy, persistent, associated with large clots or occurs together with severe pain, dizziness or other concerning symptoms.

Why is bowel preparation important?

Residual stool can obstruct the doctor's view of the bowel lining.

Completing the prescribed bowel preparation helps provide a clearer view of the colon and improves the quality of the examination. ^[^R5^]

What if a polyp is found?

Some polyps can be removed during colonoscopy and sent for laboratory analysis.
Most polyps are not cancerous, but certain polyps have the potential to become cancerous over time. Removing appropriate polyps may therefore help reduce colorectal cancer risk. ^[^R2^]

Is sedation safe?

Sedation is commonly used during gastrointestinal endoscopy, but like any medication it has potential risks.

The appropriate sedation approach depends on your health, medical history and procedure. During sedated endoscopy, patients are monitored for changes in vital signs and clinical condition. ^[^R6]

Discuss any previous reactions, medical conditions or concerns about sedation with your doctor before the procedure.

How often should I have a colonoscopy?

There is no single interval suitable for everyone.

For average-risk individuals in Singapore, HealthHub lists colonoscopy screening from age 50 at an interval of approximately 5 to 10 years. People at increased or high risk may require earlier or more frequent screening. ^[^R3^]

Your doctor can recommend an appropriate interval based on your risk factors and previous findings.

Discuss Whether Colonoscopy Is Appropriate for You

If you have been advised to undergo colonoscopy, have persistent colorectal symptoms or would like to understand your screening options, a clinical assessment can help determine what is appropriate for you.

You may book a consultation with a colorectal specialist at Sincere Surgery Centre to discuss your symptoms, risk factors and whether colonoscopy or another investigation is appropriate.

Sincere Surgery Centre – Singapore
📞 Call: +65 6665 6639
💬 WhatsApp: +65 9088 0620
📅 Book online: https://www.sinceresurgery.com.sg/contact-us

This appointment service is not intended for medical emergencies.

General Medical Information Disclaimer

This article provides general medical information and is not intended to diagnose a condition or replace consultation with a qualified healthcare professional. Seek medical advice for symptoms that concern you. Seek urgent medical attention for severe symptoms or a medical emergency.