Drug Interactions:
Thiazide Diuretics

Thiazide diuretics are commonly used to treat hypertension.

Drugs in this family include

• bendroflumethiazide (Naturetin)
• benzthiazide (Exna)
• chlorothiazide (Diurigen, Diuril)
• chlorthalidone (Hygroton, Thalitone)
• hydrochlorothiazide (Esidrix, Ezide, HydroDIURIL, Hydro-Par, Microzide, Oretic)
• hydroflumethiazide (Diucardin, Saluron)
• indapamide (Lozol)
• methyclothiazide (Aquatensen, Enduron)
• metolazone (Mykrox,  Zaroxolyn)
• polythiazide (Renese)
• quinethazone (Hydromox)
• trichlormethiazide (Diurese, Metahydrin, Naqua)
• and others

Potassium

Probable Need for Supplementation

Thiazide diuretics cause a constant and significant loss of potassium. The classic treatment for this is to eat bananas and drink orange juice. Potassium supplements are also frequently prescribed.

Medications that combine thiazides and potassium-sparing diuretics might produce an unpredictable effect on potassium levels in the body. If you are taking such medications, do not increase your potassium intake except on the advice of your physician.

Magnesium

Supplementation Possibly Helpful

Long-term use (more than 6 months) of thiazide diuretics might lead to magnesium deficiency.^1,2,3 In turn, this loss of magnesium can increase the depletion of potassium.⁴

Since magnesium deficiency is common anyway, if you take thiazide diuretics it would certainly make sense to take magnesium supplements at the U.S. Dietary Reference Intake (formerly known as the Recommended Dietary Allowance) dosage.

Calcium

Possible Dangerous Interaction

When taken over the long term, thiazide diuretics tend to increase levels of calcium by decreasing the amount excreted by the body and, indirectly, by affecting vitamin D.^5–8 It's not likely that this will cause a problem. However, since greatly increased calcium levels in the body can cause side effects such as calcium deposits, if you are using thiazide diuretics you should consult with your physician on the proper dose of calcium and vitamin D for you.

Coenzyme Q10 (CoQ10)

Supplementation Possibly Helpful

Preliminary evidence suggests that thiazide diuretics might impair the body's ability to synthesize coenzyme Q₁₀ (CoQ₁₀),⁹ a substance important for normal heart function. Although we don't know for sure that taking CoQ₁₀ supplements will provide any specific benefit, supplementing with CoQ₁₀ on general principle might be a good idea.

Zinc

Supplementation Possibly Helpful

Reportedly, thiazide diuretics can cause loss of zinc in the urine.¹⁰ Since zinc deficiency is relatively common, you should probably make sure that you get enough zinc when using these drugs.

Licorice

Possible Dangerous Interaction

If you are using thiazide diuretics, do not take licorice root. Licorice root could exacerbate the potassium depletion caused by thiazides.¹¹ However, the special form of licorice known as DGL (deglycyrrhizinated licorice) should not cause this problem.

Last reviewed March 2002 by Medical Review Board

Back to Top