Methyclothiazide
Methyclothiazide is a thiazide diuretic (water pill) used primarily to treat high blood pressure and fluid retention (edema) caused by conditions such as heart failure, liver disease, or kidney disorders. It works by helping the kidneys remove excess sodium and water from the body, which reduces blood volume and decreases blood pressure.
Methyclothiazide is a thiazide diuretic that treats high blood pressure and edema by increasing sodium and water excretion through the kidneys.
Key facts at a glance
- ATC
- C03AA08
- RxNorm
- 6860
- Generic
- Methyclothiazide
- Class
- atc-c03
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- tablet
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 500mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 250mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 400mg daily
- Maximum
- consult physician
- Frequency
- once daily
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
8 groupspregnancy
first trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks
regular fetal monitoring
Use of this medication in this population requires careful consideration of risks and benefits.
pregnancy
second third trimesteravoid if possible
discontinue if pregnancy occurs; use alternative antihypertensive
fetal growth monitoring and amniotic fluid assessment
Use of this medication in this population requires careful consideration of risks and benefits.
lactation
breastfeedingno specific adjustment
use with caution; monitor infant for signs of dehydration or electrolyte imbalance
observe infant for excessive drowsiness, feeding problems, or irritability
Use with caution and monitor for adverse effects.
pediatric_age
children under 12start at lowest effective dose
use only when other options are not available; not recommended as first-line therapy
closely monitor electrolytes, blood pressure, and renal function
Use with caution and monitor for adverse effects.
geriatric
elderly over 65start at lowest effective dose
use with caution due to age-related decline in renal function; monitor closely
regular monitoring of renal function, electrolytes, and blood pressure
Use with caution and monitor for adverse effects.
renal_impairment
mild to moderatemay require reduced dose; monitor response
use with caution; effectiveness may be reduced in severe renal impairment
monitor renal function and electrolytes more frequently
Use with caution and monitor for adverse effects.
renal_impairment
severeavoid or use with extreme caution
thiazides generally ineffective and not recommended in severe renal impairment
frequent monitoring of renal function tests
Use with caution and monitor for adverse effects.
hepatic_impairment
mild to moderateno specific dose adjustment needed
use with caution; may precipitate hepatic encephalopathy in advanced disease
monitor electrolytes and hepatic function
Use with caution and monitor for adverse effects.
Statistics and clinical data
Commonly prescribed since
General prescribing information
Drug class
Drug class information
Common uses
Common therapeutic uses
Mechanism of action
Pharmacological action
Methyclothiazide is used to treat hypertension (high blood pressure) and edema associated with heart failure, liver cirrhosis, kidney dysfunction, and certain medications. It may be used alone or as part of combination therapy for blood pressure control.
As a thiazide diuretic, methyclothiazide inhibits sodium reabsorption in the distal convoluted tubules of the kidneys. This leads to increased urinary excretion of sodium, chloride, and water, reducing extracellular fluid volume and ultimately lowering blood pressure.
Common side effects include increased urination, electrolyte imbalances (particularly low potassium), dizziness, and increased thirst. Regular monitoring of electrolytes and kidney function is recommended. Patients with gout, diabetes, or severe kidney impairment should use with caution. Alcohol and NSAIDs may worsen side effects.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 24, 2026. · Read our editorial policy