Adverse Effects of Fluconazole

Gastrointestinal Side Effects

• The Centers for Disease Control and Prevention recommends that gastrointestinal symptoms, primarily consisting of nausea and vomiting, are the most frequent adverse effects of fluconazole, occurring in a minority of patients and are generally mild and transient 1, 2, 3
• Ketoconazole, another azole, causes gastrointestinal symptoms more frequently, affecting 10-40% of patients, compared to fluconazole 2, 3

Hepatotoxicity and Dermatologic Reactions

• The Centers for Disease Control and Prevention reports that asymptomatic transaminase elevations occur in 1-13% of patients taking fluconazole, with rare cases of hepatitis and fatal hepatitis reported 1, 4
• Dermatologic reactions, including skin rash, pruritus, and rare cases of Stevens-Johnson syndrome, are recognized side effects of fluconazole 1, 2, 3

Clinical Considerations

• The Centers for Disease Control and Prevention suggests that if a patient on fluconazole presents with blood in the stool, alternative explanations, such as underlying conditions or concurrent medications, should be investigated 3, 4
• Fluconazole inhibits CYP2C9 and can increase warfarin levels, potentially causing bleeding complications, including gastrointestinal bleeding 5

Side Effects of Oral Fluconazole

Common Side Effects

• The Centers for Disease Control and Prevention (CDC) identifies gastrointestinal symptoms, including nausea (3.7%), vomiting (1.7%), abdominal pain (1.7%), diarrhea (1.5%), and dyspepsia (1%) as common adverse effects 6
• The CDC recommends monitoring for adverse effects, particularly for patients on prolonged therapy (>21 days), and considers periodic liver function monitoring 6

Special Population Considerations

• The European Respiratory Journal reports that high-dose fluconazole (>150 mg/day) during the first trimester of pregnancy is associated with congenital malformations, such as craniosynostosis and dysmorphic facies, and should be avoided 7
• The European Respiratory Journal also notes that single low doses (150 mg) of fluconazole are not associated with increased malformations 7