Interactions with Dietary Supplements

Calcium
Gentamicin has been associated with hypocalcemia (low calcium levels) in humans.¹ In a study using rats, authors reported oral calcium supplementation reduced gentamicin-induced kidney damage.² The implications of this report for humans are unclear. People receiving gentamicin should ask their doctor about monitoring calcium levels and calcium supplementation.

Magnesium
Gentamicin has been associated with urinary loss of magnesium, resulting in hypomagnesemia (low magnesium levels) in humans.^{3 4}

Potassium
Gentamicin has been associated with hypokalemia (low potassium levels) in humans.⁵

Probiotics
A common side effect of antibiotics is diarrhoea, which may be caused by the elimination of beneficial bacteria normally found in the colon. Controlled studies have shown that taking probiotic microorganisms—such as Lactobacillus casei, Lactobacillus acidophilus, Bifidobacterium longum, or Saccharomyces boulardii—helps prevent antibiotic-induced diarrhoea.⁶

The diarrhoea experienced by some people who take antibiotics also might be due to an overgrowth of the bacterium Clostridium difficile, which causes a disease known as pseudomembranous colitis. Controlled studies have shown that supplementation with harmless yeast, such as Saccharomyces boulardii⁷ or Saccharomyces cerevisiae (baker’s or brewer’s yeast),⁸ helps prevent recurrence of this infection. In one study, taking 500 mg of Saccharomyces boulardii twice daily enhanced the effectiveness of the antibiotic vancomycin in preventing recurrent clostridium infection.⁹ Therefore, people taking antibiotics who later develop diarrhoea might benefit from supplementing with saccharomyces organisms.

Treatment with antibiotics also commonly leads to an overgrowth of yeast (Candida albicans) in the vagina (candida vaginitis) and the intestines (sometimes referred to as “dysbiosis”). Controlled studies have shown that Lactobacillus acidophilus might prevent candida vaginitis.¹⁰

Vitamin B6
Gentamicin administration has been associated with vitamin B6 depletion in rabbits.¹¹ The authors of this study mention early evidence that vitamin B6 administration may protect against gentamicin-induced kidney damage.

Vitamin K
Several cases of excessive bleeding have been reported in people who take antibiotics.^{12 13 14 15} This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.¹⁶ Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

In a study of guinea pigs, a single intramuscular injection of methylcobalamin (a form of vitamin B12), in the amount of 125 mg per 2.2 pounds of body weight, given immediately after administration of gentamicin, prevented damage to the inner ear, which is a common side effect of gentamicin therapy.¹⁷ No studies have been done to determine whether the same protective effect would occur in humans.

In another animal study, injections of N-Acetyl cysteine (10 mg per 2.2 pounds of body weight per day for five days) reduced the severity of kidney damage resulting from administration of gentamicin.¹⁸