A common side effect of antibiotics is diarrhea , 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 diarrhea.¹

The diarrhea 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 boulardii ² or Saccharomyces cerevisiae (baker’s or brewer’s yeast)³—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.⁴ Therefore, people taking antibiotics who later develop diarrhea 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.⁵

A common side effect of antibiotics is diarrhea , 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 diarrhea.⁶

The diarrhea 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 boulardii ⁷ 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 diarrhea 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

Calcium supplements are known to interfere with the absorption of ciprofloxacin. The same interference has been shown to occur when calcium-fortified orange juice is taken at the same time as ciprofloxacin.¹¹

Minerals such as aluminum, calcium , copper , iron , magnesium , manganese , and zinc can bind to ciprofloxacin, greatly reducing the absorption of the drug.^{12 , 13 , 14 , 15} Because of the mineral content, people are advised to take ciprofloxacin two hours after consuming dairy products (milk, cheese, yogurt, ice cream, and others), antacids (Maalox®, Mylanta®, Tums®, Rolaids®, and others), and mineral-containing supplements.¹⁶

Preliminary research in animals has shown that fennel (Foeniculum vulgare) may reduce the absorption of ciprofloxacin.¹⁷ This interaction may be due to the rich mineral content of the herb; it has not yet been reported in humans. People taking ciprofloxacin should avoid supplementing with fennel-containing products until more is known.

Minerals such as aluminum, calcium , copper , iron , magnesium , manganese , and zinc can bind to ciprofloxacin, greatly reducing the absorption of the drug.^{18 , 19 , 20 , 21} Because of the mineral content, people are advised to take ciprofloxacin two hours after consuming dairy products (milk, cheese, yogurt, ice cream, and others), antacids (Maalox®, Mylanta®, Tums®, Rolaids®, and others), and mineral-containing supplements.²²

Minerals such as aluminum, calcium , copper , iron , magnesium , manganese , and zinc can bind to ciprofloxacin, greatly reducing the absorption of the drug.^{23 , 24 , 25 , 26} Because of the mineral content, people are advised to take ciprofloxacin two hours after consuming dairy products (milk, cheese, yogurt, ice cream, and others), antacids (Maalox®, Mylanta®, Tums®, Rolaids®, and others), and mineral-containing supplements.²⁷

Minerals such as aluminum, calcium , copper , iron , magnesium , manganese , and zinc can bind to ciprofloxacin, greatly reducing the absorption of the drug.^{28 , 29 , 30 , 31} Because of the mineral content, people are advised to take ciprofloxacin two hours after consuming dairy products (milk, cheese, yogurt, ice cream, and others), antacids (Maalox®, Mylanta®, Tums®, Rolaids®, and others), and mineral-containing supplements.³²

Minerals such as aluminum, calcium , copper , iron , magnesium , manganese , and zinc can bind to ciprofloxacin, greatly reducing the absorption of the drug.^{33 , 34 , 35 , 36} Because of the mineral content, people are advised to take ciprofloxacin two hours after consuming dairy products (milk, cheese, yogurt, ice cream, and others), antacids (Maalox®, Mylanta®, Tums®, Rolaids®, and others), and mineral-containing supplements.³⁷

In an animal study, administration of an extract of the whole plant dandelion (actually Taraxacum mongolicum, a close relative of the more common western dandelion, Taraxacum officinale) concomitantly with ciprofloxacin decreased absorption of the drug.³⁸ The authors found this was due to the high mineral content of the dandelion herb. Until further information is available, ciprofloxacin should not be taken within two hours of any dandelion supplement including teas.

Caffeine is found in coffee, tea, soft drinks, chocolate, guaraná  (Paullinia cupana), nonprescription drug products, and supplement products containing caffeine. Ciprofloxacin may decrease the elimination of caffeine from the body, causing increased caffeine blood levels and unwanted actions.³⁹ People taking ciprofloxacin may choose to limit their caffeine intake to avoid problems. They should read food, beverage, drug, and supplement labels carefully for caffeine content.

Several cases of excessive bleeding have been reported in people who take antibiotics.^{40 , 41 , 42 , 43} 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.⁴⁴ 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 K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.