These powerful diuretics are used to reduce fluid accumulation in the body.
Drugs in this family include bumetanide (Bumex), ethacrynic acid (Edecrin), furosemide (Lasix), and torsemide (Demadex) among others.
Loop 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.
Long-term use (more than 6 months) of loop diuretics might lead to magnesium deficiency. 1,2,3 In turn, magnesium depletion can increase loss of potassium. 4
Since magnesium deficiency is common anyway, taking a magnesium supplement at standard U.S. Dietary Reference Intake (formerly known as the Recommended Dietary Allowance) levels might make sense.
Evidence suggests that loop diuretics interfere with the body’s metabolism of vitamin B 1 (thiamin). 5,9,10
This effect may cause adverse consequences in one group of individuals who commonly take loop diuretics: people with heart failure. The heart depends on B 1 for proper function; therefore, this finding suggests that taking a B 1 supplement may be advisable. In fact, preliminary evidence suggests that thiamin supplementation does indeed improve heart function in individuals with congestive heart failure (CHF). 6,7,11
Licorice, too, affects potassium, and the combination of licorice and loop diuretics might cause unexpectedly rapid potassium loss. 8 However, the special form of licorice known as DGL (deglycyrrhizinated licorice) should not affect potassium levels.
Loop diuretics have been reported to cause increased sensitivity to the sun, amplifying the risk of sunburn or skin rash. Because St. John's wort and dong quai may also cause this problem, taking these herbal supplements during treatment with loop diuretics might add to this risk.
It may be a good idea to wear a sunscreen or protective clothing during sun exposure if you take one of these herbs while using a loop diuretic.
References
REF1 al-Ghamdi SM, Cameron EC, and Sutton RA. Magnesium deficiency: pathophysiologic and clinical overview. Am J Kidney Dis 24: 737–752, 1994.
REF2 Dorup I. Magnesium and potassium deficiency. Its diagnosis, occurrence and treatment in diuretic therapy and its consequences for growth, protein synthesis and growth factors. Acta Physiol Scand Suppl 618: 1–55, 1994.
REF3 Martin BJ and Millian K. Diuretic-associated hypomagnesemia in the elderly. ArchIntern Med 147: 1768–1771, 1987.
REF4 Whang R, Whang DD, and Ryan MP. Refractory potassium repletiona consequence of magnesium deficiency. Arch Intern Med 152: 40–45, 1992.
REF5 Brady JA, Rock CL, and Horneffer MR. Thiamin status, diuretic medications, and the management of congestive heart failure. J Am Diet Assoc 95: 541–544, 1995.
REF6 Seligmann H, Halkin H, Rauchfleisch S, et al. Thiamine deficiency in patients with congestive heart failure receiving long-term furosemide therapy: A pilot study. Am J Med 91: 151–155, 1991.
REF7 Shimon I, Almog S, Vered Z, et al. Improved left ventricular function after thiamine supplementation in patients with congestive heart failure receiving long-term furosemide therapy. Am J Med 98: 485–490, 1995.
REF8 Shintani S, Murase H, Tsukagoshi H, et al. Glycyrrhizin (licorice)-induced hypokalemic myopathy. Report of two cases and review of the literature. Eur Neurol 32: 44–51, 1992.
REF9 Hardig L, Daae C, Dellborg M, et al. Reduced thiamine phosphate, but not thiamine diphosphate, in erythrocytes in elderly patients with congestive heart failure treated with furosemide. J Intern Med. 2000;247:597-600.
REF10 Yue QY, Beermann B, Lindstrom B, et al. No difference in blood thiamine diphosphate levels between Swedish Caucasian patients with congestive heart failure treated with furosemide and patients without heart failure. J Intern Med. 1997;242:491-495.
REF11 Sole MJ, Jeejeebhoy KN. Conditioned nutritional requirements: therapeutic relevance to heart failure. Herz. 2002;27:174-178.