Are there any medicines I should avoid if I am taking hydrochlorothiazide (HCTZ)?

There are several medications that are contraindicated, should be avoided, or require close monitoring if they are concomitantly used with hydrochlorothiazide (HCTZ).¹

Lithium. Generally, lithium should not be given with diuretics.¹  Diuretics reduce the renal clearance of lithium and add a high risk of lithium toxicity.

Cholestyramine and Colestipol Resins. Anionic exchange resins such as cholestyramine impair the absorption of HCTZ so it may decrease the efficacy of HCTZ.¹ A single dose of either cholestyramine or colestipol resins reduce HCTZ absorption in the gastrointestinal tract by up to 85% and 43%, respectively.

Corticosteroids, ACTH. Concomitant use of corticosteroids or adrenocorticotropic hormone (ACTH) intensify electrolyte depletion, particularly hypokalemia.¹ Additive hypokalemia may occur when non-potassium sparing diuretics, such as thiazide diuretics, are given with corticosteroids.^2,3 Serum potassium levels and cardiac function should be monitored.³ Potassium supplementation may be needed.³ 

Skeletal Muscle Relaxants, Nondepolarizing (e.g., Tubocurarine). Concomitant use with HCTZ may increase the response to muscle relaxants causing an excessive sedative effect, including excessive sleepiness and muscle weakness.¹

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). In some patients, NSAIDs can reduce the diuretic, natriuretic, and antihypertensive effects of thiazide diuretics.¹  If HCTZ and NSAIDs are used concomitantly, the patient should be monitored closely to see if the diuretic reached the desired effect.

Alcohol, Barbiturates, or Narcotics. Concomitant use with HCTZ can cause potentiation of orthostatic hypotension.¹ Patients should use caution and change positions slowly to minimize orthostatic hypotension.⁴

Other Antihypertensive Drugs. Taking another antihypertensive drug with HCTZ may have an additive effect and cause hypotension.¹ However, HCTZ is commonly prescribed in combination with other antihypertensives.⁵ Patients should be aware of the potential for hypotension, but do not need to avoid taking HCTZ with other antihypertensives as prescribed by their doctor.¹

^References

1. Hydrochlorothiazide [package insert]. Morgantown, WV: Mylan Pharmaceuticals, Inc.; 2011.
2. Cohn JN, Kowey PR, Whelton PK, Prisant LM. New guidelines for potassium replacement in clinical practice: a contemporary review by the National Council on Potassium in Clinical Practice. Arch Intern Med 2000; 160 (16): 2429-2436.
3. Corticotropin, ACTH Gold Standard Drug Monograph: Elsevier; 2016.
4. Hydrochlorothiazide. Davis's Drug Guide for Nurses. 14 ed: F.A. Davis Company; 2015.
5. Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension 2017.