Chlorthalidone with Calcium Interaction Details

Brand Names Associated with Chlorthalidone

Brand Names Associated with Calcium

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 19, 2023

Interaction Effect

Increased risk of hypercalcemia

Interaction Summary

Thiazide and thiazide-like diuretics may cause hypercalcemia by decreasing renal calcium excretion. The mechanism may involve increased proximal reabsorption due to volume depletion as well as a direct effect of thiazides to increase calcium reabsorption in the distal convoluted tubule of the nephron. Concomitant ingestion of calcium salts and thiazide diuretics may predispose patients to develop the milk-alkali syndrome. The milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure) was associated with excessive ingestion of calcium carbonate (7.5 grams to 10 grams daily) and a concomitant thiazide diuretic chlorothiazide (500 mg orally daily) in one case report . Avoid excessive ingestion of calcium in any form (e.g., calcium-containing antacids, calcium supplements) while receiving thiazide or thiazide-like diuretics such as chlorthalidone. If concomitant use of calcium and chlorthalidone is necessary, consider monitoring serum calcium levels and/or parathyroid function.

Severity

Moderate

Onset

Delayed

Evidence

Theoretical

How To Manage Interaction

Concomitant use of calcium and thiazide or thiazide-like diuretics may increase the risk of hypercalcemia. Avoid excessive ingestion of calcium in any form (e.g., calcium-containing antacids, calcium supplements) while receiving thiazide or thiazide-like diuretics such as chlorthalidone. If concomitant use of calcium and chlorthalidone is necessary, consider monitoring the patient's serum calcium level and/or parathyroid function.

Mechanism Of Interaction

Inhibition of renal calcium excretion

Chlorthalidone Overview

• Chlorthalidone, a 'water pill,' is used to treat high blood pressure and fluid retention caused by various conditions, including heart disease. It causes the kidneys to get rid of unneeded water and salt from the body into the urine.

• This medicine is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

Calcium Overview

• Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not enough. Calcium is needed by the body for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve heartburn, acid indigestion, and upset stomach. It is available with or without a prescription.

• This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

Return To Our Drug Interaction Homepage

Feedback, Question Or Comment About This Information?

Definitions

Severity Categories

Contraindicated

These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.

Major

This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.

Moderate

This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.

Minor

While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.

Onset

Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.

Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.

Evidence

Level of documentation of the interaction.

Established: The interaction is documented and substantiated in peer-reviewed medical literature.

Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.

How To Manage The Interaction

Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.

It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.

Mechanism Of Interaction

The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.

Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.

Where Does Our Information Come From?

Information for our drug interactions is compiled from several drug compendia, including:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

The prescribing information for each drug, as published on DailyMED, is also used. 

Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.

The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.