Interactions with Dietary Supplements

PABA (para-aminobenzoic acid)
PABA is a compound found in foods that is considered by some to be a member of the B-vitamin family. PABA may interfere with the activity of dapsone.¹ Read supplement product labels for PABA content.

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.²

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 boulardii³ or Saccharomyces cerevisiae (baker’s or brewer’s yeast)⁴ —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.⁵ 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.⁶

Vitamin E
In large amounts, dapsone causes oxidative damage to red blood cells. This damage may be reduced by using lower amounts of dapsone. Fifteen people who took dapsone for dermatitis herpetiformis were given 800 IU of vitamin E per day for four weeks, followed by four weeks with 1,000 mg of vitamin C per day, followed by four weeks of vitamin E and vitamin C together.⁷ The authors reported only vitamin E therapy offered some protection against dapsone-induced hemolysis.

Vitamin K
A few cases of excessive bleeding have been reported in people who take antibiotics.^{8 9 10 11} 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.¹² A few 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 K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.