CLOZAPINE FDA MedWatch Voluntary U.S. Reports Summary

These tables and charts are created from 840 U.S. reports for CLOZAPINE (CLOZAPINE) voluntarily reported by individuals directly to the FDA via the MedWatch Reporting System from 2004 through July 30, 2026. Events listed on this page represent serious and often rare adverse events reported to the FDA, and often do not represent typical side effects for the medication. Find common side effects on the most recent official drug label.

For a summary of adverse events including mandatory reports submitted by pharmaceutical companies (all countries and all reporter types) to the FAERS database, View FDA FAERS CLOZAPINE Report.

Top Adverse Events Reported with CLOZAPINE (from U.S. FDA Medwatch Reports)

	Side Effect	# of FDA Reports
1	INFLAMMATION OF HEART MUSCLE	89
2	RAPID HEART RATE (TACHYCARDIA)	64
3	FEVER	51
4	CONSTIPATION	43
5	FALL	36
6	DIZZINESS	33
7	LOW WHITE BLOOD CELL COUNTS	33
8	TROPONIN INCREASED	33
9	DRUG INTERACTION	30
10	THERAPY CESSATION	28
11	LOW BLOOD PRESSURE	27
12	NAUSEA	27
13	NEUTROPHIL COUNT DECREASED	27
14	C-REACTIVE PROTEIN INCREASED	26
15	VOMITING	26
16	SHORTNESS OF BREATH	25
17	MENTAL STATUS CHANGES	25
18	EXCESS SWEATING	24
19	DRUG INEFFECTIVE	23
20	PNEUMONIA	23
21	PSYCHOTIC DISORDER	23
22	NEUROLEPTIC MALIGNANT SYNDROME	22
23	SEIZURE	22
24	SMALL INTESTINAL OBSTRUCTION	21
25	DROWSINESS	21

Search all MedWatch Reports by Keyword:

CLOZAPINE Total Medwatch Safety Reports by Patient Sex

Male	Female	Unknown	Total
533	249	58	840

Medwatch Reporter Type	Count
Consumer	122
Physician	159
Pharmacist	389
Other Health Professional	103

Top Indications

Product used for unknown indication
Schizophrenia
Schizoaffective disorder
Psychotic disorder
Dementia Alzheimer's type

Type of Outcome Reported
Serious: 685
Not Serious: 155
Note: A serious outcome means the adverse event resulted in death, a life threatening condition, hospitalization, disability, congenital anomaly, or other serious condition.

Suspected Role
Primary Suspect: 836
Concomitant Drugs: 404
Note: A single MedWatch report can list more than one drug. This summary includes CLOZAPINE identified as the suspect drug or as a concomitantly taken drug.

FDA Safety-Related Labeling Changes

CLOZARIL (CLOZAPINE) Rx Drug:
FDA Safety Communication

Strengthening an existing warning that constipation caused by the schizophrenia medicine clozapine (Clozaril, Fazaclo ODT, Versacloz) can progress to serious bowel problems Drug Safety Communication Drug Safety Communication

CLOZAPINE (CLOZAPINE) Rx Drug:
FDA Safety Communication

Strengthening an existing warning that constipation caused by the schizophrenia medicine clozapine (Clozaril, Fazaclo ODT, Versacloz) can progress to serious bowel problems Drug Safety Communication

Clozapine (CLOZAPINE) Rx Drug:
REMS

REMS has been eliminated in Feb. 2025 in order to decrease the burden on the health care delivery system and improve access. Risk still exists: monitor ANC because of risk of neutropenia. Shared FDA Risk Evaluation and Mitigation Strategy

VERSACLOZ (CLOZAPINE) Rx Drug:
FDA Safety-related Labeling Changes

Added the risk of Pericarditis in addition to myocarditis. Symptoms of myocarditis or percarditis can also include heart palpitations.

FAZACLO ODT (CLOZAPINE) Rx Drug:
FDA Safety-related Labeling Changes

CLOZARIL (CLOZAPINE) Rx Drug:
FDA Safety-related Labeling Changes

Added the risk of Pericarditis in addition to myocarditis. Symptoms of myocarditis or percarditis can also include heart palpitations. Added side effect of fecal incontinence.

Have experience (good or bad) with CLOZARIL? Rate CLOZARIL at Ask a Patient.

For serious adverse events, report them to the FDA by contacting the drug manufacturer or report directly through the MedWatch voluntary reporting form.

NOTES

This report, created by AskaPatient.com, is derived from U.S. drug-related adverse event cases that were reported directly to the FDA using the voluntary MedWatch online or paper reporting system. MedWatch is the voluntary FDA system for consumers, physicians, and others to directly report adverse reactions. The Medwatch initiative was launched in 1993 as a voluntary reporting program for consumers, physicians and other healthcare practitioners.

After processing the received forms, the FDA adds the MedWatch reports to the FDA Adverse Events Reporting System(or FAERS database.) Click here for the complete FAERS report summary, which includes mandatory reports submitted by pharmaceutical companies (worldwide) combined with the MedWatch reports. MedWatch Reports only represent about 5% of the FAERS database. For more, read "Does the FDA's Rapidly Growing Database of Adverse Events Improve Drug Safety?"

The data in this report was obtained from Open FDA. Data was last updated to include reports through January 27, 2026. The reactions, side effects, or "adverse events," represent up to the 20 most frequently occuring events in the database for a drug related to the event.

Open FDA states that it only includes the most recent version of a case report. It also adds the disclaimer: "Do not rely on Open FDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated."

FDA uses the "MedDRA" classification system to describe reported adverse reactions. MedDRA is a standardized medical terminology that facilitates sharing of regulatory information internationally. In some cases, "patient friendly" terms for the layman designated by MedDRA have been substituted for medical jargon. Please contact us with questions about this report.