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 the serum concentration of Erythromycin (Risk X: avoid combination). Pharmacology
Pharmacodynamics
Like other imidazole- and triazole-class antifungals, fluconazole inhibits the fungal cytochrome P450 enzyme 14α-demethylase. Mammalian demethylase activity is much less sensitive to fluconazole than fungal demethylase.
Another resistance mechanism employed by both C. albicans and C. glabrata is increasing the rate of efflux of the azole drug from the cell, by both ATP-binding cassette and major facilitator superfamily transporters. Other gene mutations are also known to contribute to development of resistance. C. glabrata develops resistance by up regulating CDR genes, and resistance in C. krusei is mediated by reduced sensitivity of the target enzyme to inhibition by the agent.The full spectrum of fungal susceptibility and resistance to fluconazole can be found in the TOKU-Es product data sheet. According to the United States Centers for Disease Control, fluconazole resistance among Candida strains in the U.S. is about 7%. Contraindications
Fluconazole is contraindicated in patients who:
Drink alcohol
have known hypersensitivity to other azole medicines such as ketoconazole;
are taking terfenadine, if 400 mg per day multidose of fluconazole is administered;
concomitant administration of fluconazole and quinidine, especially when fluconazole is administered in high dosages;
take SSRIs such as fluoxetine or sertraline. Side effects
Adverse drug reactions associated with fluconazole therapy include:
Common (≥1% of patients): rash, headache, dizziness, nausea, vomiting, abdominal pain, diarrhea, and/or elevated liver enzymes
Infrequent (0.1–1% of patients): anorexia, fatigue, constipation
Rare (<0.1% of patients): oliguria, hypokalaemia, paraesthesia, seizures, alopecia, Stevens–Johnson syndrome, thrombocytopenia, other blood dyscrasias, serious hepatotoxicity including liver failure, anaphylactic/anaphylactoid reactions
Very rare: prolonged QT interval, torsades de pointes
FDA is now saying treatment with chronic, high doses of fluconazole during the first trimester of pregnancy may be associated with a rare and distinct set of birth defects in infants.If taken during pregnancy it may result in harm.