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Colonoscopy Anesthesia Side Effects

author image Patricia Nevins, RN, MSN
Patricia Nevins is a registered nurse with nearly 20 years of nursing experience. She obtained her Master of Science in nursing with a focus in education from the University of Phoenix. Nevins shares her passion for healthy living through her roles as educator, nursing consultant and writer.
Colonoscopy Anesthesia Side Effects
Colonoscopy anesthesia may be oral or intravenous.

The type of anesthesia typically used during a colonoscopy is conscious sedation. Conscious sedation uses sedatives and pain relievers to reduce pain sensations and anxiety during medical procedures. Mild conscious sedation occurs through administration of either oral or intravenous medications. Side effects usually prove mild; however, some are serious and require medical intervention. People who receive colonoscopy anesthesia should learn about side effects and sign an informed consent before receiving sedation.

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Respiratory Depression

Kathleen Ouimet Perrin, PhD, author of “Understanding the Essentials of Critical Care Nursing”, emphasizes the dangers of respiratory depression during anesthesia because many sedatives inhibit the function of brain neurotransmitters involved in breathing. The author defines respiratory depression as a respiratory rate less than 12 breaths per minute with shallow ineffective breaths. Although Scott and White Hospital reports that respiratory depression occurs rarely, even mild anesthesia, such as the type used during a colonoscopy, has the potential to suppress a person’s respiratory drive.


Scott and White Hospital reports that anesthesia causes hypotension in many patients. Hypotension, low blood pressure, creates feelings of weakness, fatigue and dizziness. Before the procedure patients who take blood pressure medications should clarify with the doctor or anesthesiologist whether or not to hold the medication the morning of the procedure. Following the procedure patients should move around slowly to prevent and minimize low blood pressure effects.


Accoring to Billie Ann Wilson, Ph.D., Margaret Shannon, PhD., and Kelly Shields, PharmD., authors of “Pearson Nurse’s Drug Guide 2010”, anesthesia suppresses the autonomic nervous system, ANS. The ANS controls involuntary body functions like heart rate. Suppressing the ANS causes a slow heart rate referred to as bradycardia. This adverse effect of colonoscopy anesthesia can be reversed through provision of supplemental oxygen by procedural staff.

Risk For Injury

The American Association of Nurse Anesthetists advises that people feel hung over following anesthesia. Impaired judgment and perception results. Scott and White Hospital instructs people who receive colonoscopy sedation not to drive or operate machinery for 24 hours following the procedure. Post-sedation patients require a caregiver for the day to decrease the risk of injury. Patients may experience dizziness and in-coordination; walking around objects or up and down stairs poses a hazard to patients.

Nausea and Vomiting

Sedatives and pain relievers frequently cause nausea and vomiting. Because of these side effects patients do not eat or drink after midnight on the night prior to a colonoscopy, says Scott and White Hospital. Following the procedure, patients should drink clear fluids for the first few hours after anesthesia to prevent nausea and vomiting.

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