U.S. flag An official website of the United States government
  1. Home
  2. Safety
  3. MedWatch: The FDA Safety Information and Adverse Event Reporting Program
  4. Medical Product Safety Information
  5. Clozaril, Fazaclo ODT, Versacloz (clozapine): Drug Safety Communication - FDA Strengthens Warning That Untreated Constipation Can Lead to Serious Bowel Problems
  1. Medical Product Safety Information

Clozaril, Fazaclo ODT, Versacloz (clozapine): Drug Safety Communication - FDA Strengthens Warning That Untreated Constipation Can Lead to Serious Bowel Problems

[Posted: January 28, 2020]

AUDIENCE: Patient, Health Professional

ISSUE: FDA is strengthening an existing warning that constipation caused by the schizophrenia medicine clozapine (Clozaril, Fazaclo ODT, Versacloz, generics) can, uncommonly, progress to serious bowel complications. This can lead to hospitalization or even death if constipation is not diagnosed and treated quickly.

BACKGROUND: Clozapine affects how the intestines (bowels) function in the majority of patients. It produces effects ranging from constipation (trouble having a bowel movement), which is a common occurrence, to serious but uncommon bowel problems, including complete blockage of the bowel.

RECOMMENDATION: Patients should contact your health care professional if:

  • their bowel movements are less frequent than normal.
  • they do not have a bowel movement at least three times a week.
  • they have hard or dry stools.
  • they have difficulty passing gas.

Patients should contact your health care professional right away if you have symptoms which can be associated with serious bowel problems such as:

  • nausea
  • vomiting
  • bloating or belly swelling, or belly pain.

Health care professionals should:

  • Evaluate bowel function before starting a patient on clozapine.
  • Avoid co-prescribing clozapine with other anticholinergic medicines that can cause gastrointestinal hypomotility.
  • Advise patients frequently of the significant risk of constipation and life-threatening bowel issues and the need to stay hydrated to prevent constipation.
  • Question patients about the frequency and quality of their bowel movements throughout treatment.
  • Advise patients to contact a health care professional right away if they have difficulty having a bowel movement or passing stools, do not have a bowel movement at least three times a week or less than their normal frequency, or are unable to pass gas.
  • Monitor patients for symptoms of potential complications associated with gastrointestinal hypomotility such as nausea, abdominal distension or pain, and vomiting.
  • Consider prophylactic laxative treatment when starting clozapine in patients with a history of constipation or bowel obstruction.

Healthcare professionals and patients are encouraged to report adverse events or side effects related to the use of these products to the FDA's MedWatch Safety Information and Adverse Event Reporting Program:

  • Complete and submit the report online
  • Download form or call 1-800-332-1088 to request a reporting form, then complete and return to the address on form or submit by fax to 1-800-FDA-0178

[01/28/2020 - Drug Safety Communication - FDA] 

MedWatch Safety Information

Clinically important medical product safety alerts and timely information about the products you use, prescribe, or dispense every day.