hydrochlorothiazide : Complexes, Storage & Clinical Research on Healthline.com

Drug or Test	Interaction	Comments
Alcohol	Increased risk of postural hypotension with thiazides
Amphetamine	Thiazides may cause slightly more alkaline urinary pH; may decrease urinary excretion of some amines (e.g., amphetamine) with concurrent use	Urine pH change is not great during thiazide use and, toxic blood concentrations of amines usually do not occur Monitor for signs of toxicity after initiation of thiazides in patients receiving amphetamine
Amphotericin B	Additive/potentiated potassium loss	Severe potassium depletion may occur when used concomitantly
Anticoagulants, oral	Postulated that may antagonize oral anticoagulant effects	Confirmatory evidence is lacking
Antidiabetic agents (sulfonylureas)	Thiazide hyperglycemic effect may exacerbate diabetes mellitus, increase antidiabetic agent requirements, and/or cause temporary loss of diabetic control or secondary failure to antidiabetic agent
Barbiturates	Increased risk of postural hypotension with thiazides
Cholestyramine or colestipol resin	May bind thiazides, reduce their GI absorption, with cholestyramine reportedly producing greater binding in vitro	Administer thiazides at least 2 hours before cholestyramine or colestipol when used concomitantly
Corticosteroids	Additive/potentiated potassium loss	Severe potassium depletion may occur when used concomitantly
Corticotropin	Additive/potentiated potassium loss	Severe potassium depletion may occur when used concomitantly
Diazoxide	May potentiate diazoxide hyperglycemic, hypotensive, and hyperuricemic effects	Use concomitantly with caution
Digitalis glycosides	Thiazide-induced electrolyte disturbances (principally hypokalemia, but also hypomagnesemia and hypercalcemia) may increase digitalis toxicity risk	Perform periodic electrolyte determinations with concomitant use; correct hypokalemia if warranted
Hypotensive agents	Increased hypotensive effects of most other hypotensive agents Addition of thiazide to stabilized regimen with potent hypotensive agent (e.g., guanethidine sulfate, methyldopa, ganglionic blocking agent) may cause severe postural hypotension	Usually used to therapeutic advantage
Insulin	May exacerbate diabetes mellitus, increase insulin requirements, cause temporary loss of diabetic control, or secondary failure to insulin
Lithium	Thiazides (sometimes used with lithium to reduce lithium-induced polyuria) reduced renal lithium clearance within several days Can increase serum lithium concentrations and the risk of lithium intoxication	Occasionally used to therapeutic advantage to reduce lithium-induced polyuria, but reduce lithium dosage by about 50% and monitor serum lithium carefully. Generally, avoid concomitant use because of increased lithium toxicity risk.
Methenamine	Urinary alkalinization may decrease the effectiveness of methenamine compounds which require a urinary pH of ≤5.5 for optimal activity	Monitor urine pH during concurrent therapy
Neuromuscular blocking agents (e.g., tubocurarine chloride or gallamine triethiodide [both no longer commercially available in the US])	May cause prolonged neuromuscular blockade	Confirmatory evidence lacking
NSAIAs	Increased risk of NSAIA-induced renal failure secondary to prostaglandin inhibition and decreased renal blood flow NSAIAs may interfere with the natriuretic, diuretic, and antihypertensive response to diuretics	Monitor closely for possible adverse effects and/or attenuation of diuretic-induced therapeutic effects during concomitant use
Opiates	Increased risk of postural hypotension with thiazides
Probenecid	Blocks thiazide-induced uric acid retention Also blocks renal tubular secretion of thiazide, but effect on thiazide duration of action apparently not studied Apparently enhances excretion of calcium, magnesium, and citrate during thiazide therapy, but urinary calcium concentrations remain below normal Sodium, potassium, ammonia, chloride, bicarbonate, phosphate, and titratable acid excretion apparently not affected by concomitant probenecid and thiazide therapy	Used to therapeutic advantage
Quinidine	Thiazides may cause slightly more alkaline urinary pH; may decrease urinary excretion of some amines (e.g., quinidine) with concurrent use	Urine pH change is not great during thiazide use, and toxic blood concentrations of amines usually do not occur Monitor for signs of toxicity after initiation of thiazide
Test, Amylase (serum)	Values may be increased substantially in both asymptomatic patients and in patients developing acute pancreatitis who are receiving thiazides
Test, Corticosteroids (urinary) (Glenn-Nelson technique)	Decreased values by interfering in vitro with the absorbance in the modified Glenn-Nelson technique for urinary 17-hydroxycorticosteroids; may also decrease urinary cortisol excretion	Importance of effect on urinary corticosteroids is unclear
Test, Estrogens (spectrophotometric assay of total urinary estrogen; assay of estradiol)	Hydrochlorothiazide causes falsely decreased values by interfering with formation of the Kober chromogen, and with the assay of estriol by degrading estriol at the acid hydrolytic stage of the assay; does not occur with chlorothiazide
Test, Histamine for pheochromocytoma	False-negative results
Test, Parathyroid function tests	May elevate serum calcium in the absence of known disorders of calcium metabolism	Discontinue thiazides prior to performing parathyroid function tests
Test, Phenolsulfonphthalein (PSP)	Thiazides compete with phenolsulfonphthalein (PSP) for secretion by the proximal renal tubules	Importance unknown
Test, Phentolamine	False-negative results
Test, Protein-bound iodine (PBI)	Values may be decreased, although usually not to subnormal
Test, Triiodothyronine resin uptake	Decreased slightly, but 24-hour I 131 uptake is not affected
Test, Tyramine	False-negative results
Vasopressors (e.g., norepinephrine)	Possible decreased arterial responsiveness to vasopressor amines	Clinical importance not established; decrease in pressor response not sufficient to preclude vasopressor use

Hydrochlorothiazide
LL / H 14 25 mg	MYLAN 810 / MYLAN 810 12.5 mg	Z 2083 25 mg	WATSON 347 12.5 mg 12.5 mg
Z 2089 50 mg
Microzide
MICROZIDE / 12.5 mg 12.5 mg

Drug Notebook

Generic Name: hydrochlorothiazide

Drug Interactions

Specific Drugs and Laboratory Tests