Drug class · FAERS comparison

Thiazide Diuretic side effects compared: 4 drugs, 153,936 FDA adverse event reports

Class as assigned in the FDA label (Established Pharmacologic Class) · data 2026-09-14

How to read this page. Report counts are not incidence rates: a drug with more reports is usually older, more widely used or more publicised, not more dangerous. Signals are screened against each product's FDA label on its own page; a term flagged across most of a class usually reflects the shared mechanism or the shared patient population.

Members

Drug	FAERS reports	Serious	Death outcome	Boxed warning	Top labeled signals	Unlabeled (unassessed)
Hydrochlorothiazide	144,362	67%	10,118	–	Vasculitis; Tension headache; Respiratory symptom	Hyponatraemia; Macular degeneration
Olmesartan Medoxomil-Hydrochlorothiazide	7,404	69%	178	boxed	Acute kidney injury; Weight decreased; Chronic kidney disease	Gastrooesophageal reflux disease; Haemorrhoids
Chlorothiazide (Diuril)	1,253	80%	198	–	Respiratory failure; Respiratory distress; Acute respiratory failure	Cardiac arrest; Hypoxia
Chlorothiazide (Diuril)	917	81%	137	–	Respiratory failure; Respiratory distress	–

Class-wide signals (flagged in at least 2 of 4 members)

Reaction	Members flagged	Median PRR	Reports (sum)	In label
Pulmonary hypertension	2/4	28.1	61	0/2 members' labels
Fluid overload	2/4	27.2	41	0/2 members' labels
Pulmonary arterial hypertension	2/4	25.0	38	0/2 members' labels
Respiratory distress	2/4	18.1	53	2/2 members' labels
Serotonin syndrome	2/4	15.5	30	0/2 members' labels
Respiratory failure	2/4	13.7	104	2/2 members' labels
Shock	2/4	11.7	27	0/2 members' labels

Member-specific signals (flagged in exactly one drug)

Reaction	Drug	Reports	PRR	Label screen
Cardiospasm	Hydrochlorothiazide	398	370.1	Likely indication confounding
Vaginal flatulence	Hydrochlorothiazide	188	234.7	Not in label — unassessed
Immunisation	Hydrochlorothiazide	257	213.9	Not in label — unassessed
Palmoplantar keratoderma	Hydrochlorothiazide	386	169.0	Not in label — unassessed
Hiatus hernia	Olmesartan Medoxomil-Hydrochlorothiazide	668	153.8	Not in label — unassessed
Haemorrhoids	Olmesartan Medoxomil-Hydrochlorothiazide	974	148.6	Not in label — unassessed
Coeliac disease	Olmesartan Medoxomil-Hydrochlorothiazide	318	94.8	Not in label — unassessed
Neurologic neglect syndrome	Hydrochlorothiazide	180	68.7	Not in label — unassessed
Irritable bowel syndrome	Olmesartan Medoxomil-Hydrochlorothiazide	469	63.6	Not in label — unassessed
Diverticulitis	Olmesartan Medoxomil-Hydrochlorothiazide	593	62.1	Not in label — unassessed
Total lung capacity abnormal	Hydrochlorothiazide	104	54.4	Not in label — unassessed
Gastrooesophageal reflux disease	Olmesartan Medoxomil-Hydrochlorothiazide	1,357	48.7	Not in label — unassessed
Pulmonary vasculitis	Hydrochlorothiazide	131	47.7	Labeled (related wording)
Amaurosis fugax	Hydrochlorothiazide	242	42.3	Not in label — unassessed
Carotid artery thrombosis	Hydrochlorothiazide	183	39.5	Not in label — unassessed
Atrial tachycardia	Hydrochlorothiazide	436	37.7	Not in label — unassessed
Milk-alkali syndrome	Hydrochlorothiazide	102	34.6	Not in label — unassessed
Pruritus genital	Hydrochlorothiazide	407	30.6	Not in label — unassessed
Gastric ulcer	Olmesartan Medoxomil-Hydrochlorothiazide	190	28.5	Not in label — unassessed
Adjustment disorder	Hydrochlorothiazide	183	23.6	Not in label — unassessed
Inflammatory bowel disease	Olmesartan Medoxomil-Hydrochlorothiazide	77	22.3	Not in label — unassessed
Impaired gastric emptying	Olmesartan Medoxomil-Hydrochlorothiazide	99	22.2	Labeled (related wording)
Gastroenteritis	Olmesartan Medoxomil-Hydrochlorothiazide	112	21.9	Labeled adverse reaction
Cholecystitis	Olmesartan Medoxomil-Hydrochlorothiazide	91	21.8	Not in label — unassessed
Carotid artery occlusion	Hydrochlorothiazide	480	21.8	Not in label — unassessed

Common questions

Which thiazide diuretic has the most FDA adverse event reports?

Hydrochlorothiazide has the most FAERS co-reports in this class (144,362), followed by Olmesartan Medoxomil-Hydrochlorothiazide (7,404). Report volume tracks how widely and how long a drug has been used, and how much attention it has had, far more than its risk.

Which side effects are shared across thiazide diuretic drugs?

Reaction terms flagged in at least half of the 4 members include pulmonary hypertension, fluid overload, pulmonary arterial hypertension, respiratory distress, serotonin syndrome. A term shared across a class usually reflects the shared mechanism (or the shared patient population) rather than one product.

Does a FAERS signal mean the drug causes the reaction?

No. These are disproportionality signals from voluntary reports with no denominator. Each is screened against the FDA label (known vs unlabeled) on the drug pages; causality needs temporality, dose-response, plausibility and trial or cohort evidence.

Sources: openFDA FAERS pair statistics (OpenPV build 2026-09-14), FDA labels via openFDA, seriousness and death counts from openFDA count queries. Generated 2026-10-08. Not medical advice.