What is the best course of treatment for a female patient of childbearing age with vomiting and bacterial vaginosis (BV)?

Treatment of Vomiting with Bacterial Vaginosis in Women of Childbearing Age

For a woman of childbearing age with both vomiting and bacterial vaginosis, use intravaginal metronidazole gel 0.75% (one full applicator daily for 5 days) or intravaginal clindamycin cream 2% (one full applicator at bedtime for 7 days) to avoid exacerbating nausea and vomiting that would occur with oral metronidazole. 1, 2

Why Avoid Oral Metronidazole in This Context

• Oral metronidazole causes significant gastrointestinal side effects, particularly metallic taste, nausea, and vomiting, which would worsen the patient's existing vomiting 3
• The CDC recommends metronidazole 500 mg orally twice daily for 7 days as first-line therapy for BV with a 95% cure rate, but this is inappropriate when the patient is already vomiting 1, 2
• Metronidazole causes nausea and vomiting at significantly higher rates than clindamycin (RR 0.23, meaning clindamycin causes 77% fewer GI events) 3

Recommended Treatment Approach

First-Line Intravaginal Options

• Metronidazole gel 0.75%, one full applicator (5g) intravaginally once daily for 5 days achieves 78-84% cure rates at 4 weeks and avoids systemic GI side effects 1, 2
• Clindamycin cream 2%, one full applicator (5g) intravaginally at bedtime for 7 days achieves similar 78-84% cure rates and causes fewer adverse events than oral metronidazole 1, 2

Critical Safety Warning for Intravaginal Clindamycin

• Clindamycin cream is oil-based and may weaken latex condoms and diaphragms for up to 5 days after use 2
• Patients must be counseled about alternative contraception during treatment 2

Address the Vomiting Separately

• The vomiting requires separate evaluation as it is not a typical symptom of bacterial vaginosis 1
• BV characteristically presents with homogeneous white discharge, fishy odor, vaginal pH >4.5, and clue cells—but not systemic symptoms like vomiting 1, 2
• Investigate other causes of vomiting (pregnancy, gastroenteritis, other infections) while treating the BV 4

Pregnancy Considerations (Critical in Childbearing Age Women)

• Rule out pregnancy first before initiating any BV treatment, as this fundamentally changes management 5, 6
• If pregnant and symptomatic with BV, oral metronidazole 250 mg three times daily for 7 days is recommended despite the vomiting, as BV in pregnancy causes serious complications including preterm birth, premature rupture of membranes, and postpartum endometritis 5
• Pregnant patients should not receive the single 2g metronidazole dose as it results in higher serum levels that reach fetal circulation 6
• The one-day treatment regimen should not be used in pregnancy 6

When Oral Therapy Becomes Necessary

• If intravaginal therapy fails or the patient cannot use intravaginal preparations, oral clindamycin 300 mg twice daily for 7 days causes 75% fewer adverse events than metronidazole and avoids metallic taste entirely 1, 2, 3
• Once vomiting resolves, oral metronidazole 500 mg twice daily for 7 days remains the gold standard with the highest cure rate (95%) 1, 2

Follow-Up Considerations

• Follow-up visits are unnecessary if symptoms resolve 2
• Male partner treatment is not recommended as it does not prevent BV recurrence 1, 2
• If the patient is pregnant or at high risk for pregnancy complications, follow-up evaluation at 1 month after treatment is recommended to verify cure 7, 5