The effect of amoxycillin on salivary nitrite concentrations: an important mechanism of adverse reactions?

Br J Clin Pharmacol. 1995 Apr;39(4):460-2. doi: 10.1111/j.1365-2125.1995.tb04479.x.


Broad spectrum antibiotics are known to predispose towards oral candidiasis and gastroenteritis. Oral nitrite synthesis by commensal bacteria may be important in protecting the mouth and lower intestine from pathogenic organisms, including Candida albicans. The effect of 2 days administration of the broad spectrum antibiotic amoxycillin on salivary nitrite concentration, following a 200 mg potassium nitrate oral load, was studied in 10 healthy volunteers. The Cmax fell by 40% and the AUC was reduced by 1227 microM h (43%, 95% CI 273, 2181, P < 0.006) in the antibiotic treated group when compared with control. These findings suggest that destruction of nitrate reductase containing bacteria in the mouth by antibiotics may explain an increased incidence of infection with Candida and other pathogens.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial

MeSH terms

  • Adult
  • Amoxicillin / adverse effects
  • Amoxicillin / pharmacology*
  • Amoxicillin / therapeutic use
  • Candida albicans / drug effects
  • Candidiasis, Oral / drug therapy
  • Gastroenteritis / drug therapy
  • Humans
  • Male
  • Nitrates / administration & dosage
  • Nitrates / metabolism*
  • Potassium Compounds / administration & dosage
  • Potassium Compounds / metabolism
  • Saliva / drug effects*
  • Saliva / metabolism


  • Nitrates
  • Potassium Compounds
  • Amoxicillin
  • potassium nitrate