FDA Adverse Events Reports (FAERS) Summary for HYDREA

These tables and charts are based on 6,276 total reports for HYDREA (HYDROXYUREA) received by the FDA Adverse Event Reporting System (FAERS) from 2004 through April 28, 2026.

This FAERS total includes 6,174 pharmaceutical company-submitted and non-U.S. FAERS reports and 102 U.S. consumer or healthcare provider-submitted MedWatch reports. For a separate summary of the 102 U.S. reports filed via the FDA MedWatch voluntary reporting system, view our FDA MedWatch HYDREA summary report. (See notes section below for explanation of FDA’s mandatory and voluntary reporting system.)

Top 20 Adverse Effects Associated with HYDREA (reported in FAERS Database)

	Side Effect	# of FDA Reports
1	OFF LABEL USE	459
2	FATIGUE	410
3	ANEMIA	395
4	FEVER	348
5	NAUSEA	313
6	DIARRHEA	307
7	PLATELET COUNT DECREASED	283
8	HAEMOGLOBIN DECREASED	277
9	DEATH	273
10	SHORTNESS OF BREATH	254
11	HEADACHE	243
12	PNEUMONIA	236
13	PAIN	219
14	WHITE BLOOD CELL COUNT INCREASED	214
15	DIZZINESS	208
16	SICKLE CELL ANAEMIA WITH CRISIS	203
17	LACK OF STRENGTH AND ENERGY (ASTHENIA)	202
18	PLATELET COUNT INCREASED	200
19	MALAISE	198
20	THROMBOCYTOPENIA	197
21	VOMITING	187
22	DRUG INEFFECTIVE	180
23	PAIN IN EXTREMITY	175
24	JOINT PAIN	171
25	FALL	168
26	DECREASED APPETITE	156
27	WEIGHT DECREASED	149
28	ITCHING	140
29	SPLEEN ENLARGED	137
30	MYELOFIBROSIS	129
31	RASH	129
32	WHITE BLOOD CELL COUNT DECREASED	127
33	PANCYTOPENIA	125
34	SWELLING OF LIMBS	124
35	BACK PAIN	123
36	ACUTE MYELOID LEUKAEMIA	120
37	WEIGHT INCREASED	119
38	SKIN ULCER	113
39	COUGH	112
40	ABDOMINAL PAIN	104
41	STROKE	101
42	PLEURAL EFFUSION	101
43	CONSTIPATION	99
44	BLOOD CREATININE INCREASED	97
45	HEART FAILURE	93
46	DEHYDRATION	92
47	LEUKOCYTOSIS	92
48	KIDNEY FAILURE	92
49	SEPSIS	92
50	INTERSTITIAL LUNG DISEASE	89
51	ABDOMINAL PAIN UPPER	86
52	NOSEBLEED	86
53	KIDNEY IMPAIRMENT	86
54	URINARY TRACT INFECTION	85
55	BRUISE	84
56	CANCER PROGRESSION	83
57	MUSCLE PAIN	83
58	GENERAL PHYSICAL HEALTH DETERIORATION	82
59	ACUTE KIDNEY INJURY	81
60	RED BLOOD CELL COUNT DECREASED	81
61	FEELING ABNORMAL	80
62	HAEMATOCRIT DECREASED	80
63	FEBRILE NEUTROPENIA	79
64	BLOOD LACTATE DEHYDROGENASE INCREASED	78
65	CHEST PAIN	78
66	DIFFICULTY SWALLOWING	78
67	DISEASE PROGRESSION	77
68	TUMOUR LYSIS SYNDROME	77
69	LOW BLOOD PRESSURE	76
70	INTENTIONAL PRODUCT USE ISSUE	76
71	CONDITION AGGRAVATED	72
72	ABDOMINAL DISCOMFORT	71
73	CONFUSIONAL STATE	70
74	PRODUCT DOSE OMISSION ISSUE	70
75	PRODUCT USE ISSUE	69
76	LOWER LIMBS SWELLING	67
77	DROWSINESS	67
78	ATRIAL FIBRILLATION	66
79	BLEEDING	66
80	LIVER FUNCTION ABNORMAL	66
81	DRUG INTERACTION	65
82	INFECTION	65
83	CONGESTIVE HEART FAILURE	64
84	LOW WHITE BLOOD CELL COUNTS	64
85	RESPIRATORY FAILURE	63
86	STOMATITIS	63
87	GASTROINTESTINAL BLEEDING	61
88	SKIN REDNESS	60
89	GAIT DISTURBANCE	60
90	HIGH BLOOD PRESSURE	59
91	PULMONARY EMBOLISM	58
92	SERUM FERRITIN INCREASED	58
93	ASPARTATE AMINOTRANSFERASE INCREASED	57
94	CHILLS	57
95	ABDOMINAL DISTENSION	56
96	BONE MARROW FAILURE	55
97	DRUG INTOLERANCE	55
98	BLOOD BILIRUBIN INCREASED	54
99	BONE PAIN	53
100	HYPONATRAEMIA	53

Latest Known Outcomes for Reactions Reported for HYDREA

	Latest Known Outcome for Reported Reactions	Number of Cases
1	Unknown Outcome	3012
2	Patient recovered	1567
3	Patient has not recovered/symtoms have not resolved	1314
4	Patient is recovering/symptoms resolving	993
5	Patient died	825
6	Patient has recovered but has consequent health issues	98

Search all MedWatch and FAERS by keyword:

HYDREA Total Reports

Male	Female	Unknown	Total
2424	2654	1198	6,276

Top Countries Reporting

	Country	Number of Reports
1	United States	1954
2	France	1082
3	Japan	963
4	Brazil	247
5	Canada	139
6	Spain	108
7	United Kingdom	63
8	EU	52
9	Belgium	42
10	Australia	41

Outcomes for Reports

Serious: 5260
Not Serious: 1015
Note: A serious outcome means the adverse event resulted in death, a life threatening condition, hospitalization, disability, congenital anomaly, or other serious condition.

Top Indications

Top Companies Reporting

Safety-Related FDA Updates

HYDREA (HYDROXYUREA) Rx Drug:
Safety-related Labeling Changes

Have experience (good or bad) with HYDREA? Rate HYDREA 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 the cases for HYDREA reported to the United States Food and Drug Administration (FDA) FDA Safety Information and Adverse Event Reporting System (FAERS) and obtained from Open FDA. Data was last updated with reports received through April 28, 2026.

This summary includes ALL reports where the drug is a "primary OR secondary OR suspected interacting" drug. Typically, reports are filed for the most serious type or "event" and do not represent incidental or minor side effects. The majority of these reports are mandatory reports submitted by pharmaceutical companies, who receive complaints from consumers. 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. This report also features counts of latest known outcomes associated with reported side effects, but does not provide the specific outcomes for specific adverse events.

Adverse Event Reports are submitted to the FAERS database by pharmaceutical companies (mandatory reporting is required by manufacturers, distributors, or importers). Health care providers such as doctors (voluntary reporting), and patients themselves (voluntary reporting) report to the FDA directly through the MedWatch program. Those MedWatch reports are coded and included in the FAERS database. This report mainly consists of the mandatory reports, because the MedWatch reports are a small percentage (3 - 5%) of total reports. Link to the MedWatch summary report at the top of the page for a summary of the directly reported (voluntary) adverse events for this drug.The number of reports included here might differ somewhat from the number of reports in the downloadable quarterly FAERS reports and in the online FAERS dashboard, due to lags in reporting, drug name differences, duplicates, and other factors. Open FDA states that it only includes the most recent version of a case report. It also adds the disclaimer: "Do not rely on openFDA 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 or comments about this report.