Med of the Month: Hydrochlorothiazide

Hydrochlorothiazide may not sound glamorous, but it’s one of the quiet workhorses of modern medicine. This little “water pill” has been helping hearts, kidneys, and blood vessels since the 1960s – and it’s still prescribed millions of times each year. Whether your patient takes it for high blood pressure, swelling, or heart failure, it can influence what happens in your chair more than you might think. From dry mouth to dizzy spells to the dreaded “triple whammy”, its dental implications are subtle but significant.

Generic Name: Hydrochlorothiazide

Brand Name(s): HydroDIURIL, Esidrix, Microzide, Oretic

Pronunciation: HYE dro KLOR o THY a zide

About this drug:

• Hydrochlorothiazide (aka HCTZ) is a thiazide diuretic that is used to treat:

  • fluid retention caused by congestive heart failure or liver and kidney disorders.

  • edema caused by taking steroids or estrogen.

  • high blood pressure.

Dentistry-related tidbits:

• Xerostomia risk: Hydrochlorothiazide may cause dry mouth. For patients with a high caries rate, consider prescribing a fluoride supplement and increasing the frequency of preventive dental visits.

• Hematologic effects: The drug can cause thrombocytopenia (low platelet count). Monitor for unusual bleeding or bruising during oral exams.

• Salivary gland involvement: Cases of sialadenitis (inflammation of the salivary glands) have been reported. Patients may present with gland tenderness or swelling.

• Frequent urination: Because Hydrochlorothiazide increases urine output, patients may need to pause treatment for restroom breaks. Plan longer appointments accordingly.

• Orthostatic effects: Elderly patients in particular may experience dizziness, lightheadedness, or hypotension when standing. Have patients sit upright in the chair for a few minutes before dismissal and assist them when standing or walking.

• Local anesthetic considerations: Common agents such as articaine, bupivacaine, lidocaine, mepivacaine, and ropivacaine can further lower blood pressure when combined with Hydrochlorothiazide. Monitor vital signs and adjust dosing if needed.

• Epinephrine interactions: Epinephrine in local anesthetics can contribute to hypokalemia, QT prolongation, arrhythmias, and increased blood pressure when used with Hydrochlorothiazide. Consider limiting the total epinephrine dose to 0.04 mg.

  • Note: According to the ADA, local anesthetics containing epinephrine are not contraindicated in hypertensive patients whose blood pressure is well controlled with medication.

• CNS depressants: Combining Hydrochlorothiazide with narcotics, certain benzodiazepines, or muscle relaxants can intensify hypotension and cause orthostasis or syncope. Use caution when prescribing or administering sedatives.

• Corticosteroids: Co-administration with steroids may exacerbate hypertension.

• Renal considerations: The following medications can increase the risk of kidney impairment when taken with Hydrochlorothiazide:

  • NSAIDs (including aspirin and combination products), which can also raise blood pressure.

  • Antivirals such as acyclovir or valacyclovir.

  • Lincosamide antibiotics such as clindamycin.

• “Triple whammy” warning: If a patient is taking both an ACE inhibitor (e.g., lisinopril) or an ARB (e.g., losartan) and Hydrochlorothiazide, avoid prescribing any NSAID, even short-term or OTC forms. The combination can cause acute kidney injury, even in patients without preexisting renal disease.

• Staying safe: It’s important to use a tool like the MedAssent DDS Rx Check to practice safe prescribing.

Fun facts:

• Hydrochlorothiazide is a thiazide-type diuretic, meaning it contains a benzothiadiazine ring structure.

• Approved in 1959, Hydrochlorothiazide remains one of the oldest yet most commonly prescribed antihypertensives in the world.

• It can mess with electrolytes. The medication can lower potassium and sodium levels, which matters for epinephrine use, anesthesia safety, and cardiac rhythm.

Get more dental-specific drug intel with the Digital Drug Handbook (web) or BrushUp Rx (mobile app).