QT interval, such as electrolyte imbalance or use of other drugs that may prolong the QT interval (particularly cisapride and pimozide). Fluconazole has also rarely been associated with severe or lethal hepatotoxicity, so liver function tests are usually performed regularly during prolonged fluconazole therapy. In addition, it is used with caution in patients with pre-existing liver disease. Some people are allergic to azoles, so those allergic to other azole drugs might be allergic to fluconazole. That is, some azole drugs have adverse side-effects. Some azole drugs may disrupt estrogen production in pregnancy, affecting pregnancy outcome. Fluconazole taken at low doses is in FDA pregnancy category C. However, high doses have been associated with a rare and distinct set of birth defects in infants. If taken at these doses, the pregnancy category is changed from category C to category D. Pregnancy category D means there is positive evidence of human fetal risk based on human data. In some cases, the potential benefits from use of the drug in pregnant women with serious or life-threatening conditions may be acceptable despite its risks. Fluconazole should not be taken during pregnancy or if one could become pregnant during treatment without first consulting a doctor. Oral fluconazole is not associated with a significantly increased risk of birth defects overall, although it does increase the odds ratio of tetralogy of Fallot, but the absolute risk is still low. Women using fluconazole during pregnancy have a 50% higher risk of spontaneous abortion. Fluconazole should not be taken with cisapride (Propulsid) due to the possibility of serious, even fatal, heart problems. In rare cases, severe allergic reactions including anaphylaxis may occur. Powder for oral suspension contains sucrose and should not be used in patients with hereditary fructose, glucose/galactose malabsorption or sucrase-isomaltase deficiency. Capsules contain lactose and should not be given to patients with rare hereditary problems of galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption Interactions Fluconazole is an inhibitor of the human cytochrome P450 system, particularly the isozyme CYP2C19 (CYP3A4 and CYP2C9 to lesser extent) In theory, therefore, fluconazole decreases the metabolism and increases the concentration of any drug metabolised by these enzymes. In addition, its potential effect on QT interval increases the risk of cardiac arrhythmia if used concurrently with other drugs that prolong the QT interval. Berberine has been shown to exert synergistic effects with fluconazole even in drug-resistant Candida albicans infections. Fluconazole may increase