How are antibiotics used?

The symptoms of bacterial vaginosis are usually treated with the antibiotics clindamycin or metronidazole – in the form of a cream, vaginal suppositories or tablets, or oral tablets (to be swallowed). The treatment can last 2 to 7 days depending on the exact drug and form used, the dose, and the severity of the symptoms. You can talk to your doctor about what type of treatment is most suitable for you.

If you've been prescribed antibiotics, it's important to make sure you use them correctly. That especially means using the medicine regularly and for as long as prescribed: If you stop early – for instance, because the symptoms have already cleared up – resistant strains of bacteria may develop.

How effective are antibiotics?

Clindamycin and metronidazole are very effective against vaginosis symptoms. Research on treatment with clindamycin creams found that the symptoms went away within 1 to 2 weeks in

• 88% of the women who used clindamycin, and
• 50% of the women who used a placebo (fake treatment).

Several studies have also shown that clindamycin and metronidazole are similarly effective: In the studies comparing these two antibiotics, over 90% of the women had no symptoms after treatment – regardless of which of the medications they had used.

Bacterial vaginosis might come back after a few weeks. That happens quite often: About half of all women have symptoms again one year after the first infection. If you keep getting bacterial vaginosis, it's a good idea to discuss the prevention options with your doctor.

Researchers have also looked into whether it's a good idea for your partner to take antibiotics too. But that wasn’t shown to speed up the recovery time or prevent the infection from coming back.

What are the side effects?

The antibiotics don’t only kill gardnerella bacteria. They also kill useful bacteria in the vagina that help to keep other germs in check. As a result, treatment with antibiotics can sometimes end up causing a vaginal yeast infection (thrush). This happens in about 10% of women who use clindamycin or metronidazole. The typical symptoms of vaginal thrush include itching and thick, white discharge. Thrush can also be treated with medication.

Antibiotics occasionally have other side effects too. About 10% of women who take metronidazole tablets say that the tablets leave a metallic taste in their mouth. Less commonly, they cause nausea and vomiting. Clindamycin is very well tolerated when used as a cream. It has no known potential side effects apart from yeast infections (thrush).

Can lactic acid bacteria help?

Lactic acid bacteria are believed to help restore a healthy balance of germs in the vagina (healthy vaginal flora) and keep harmful bacteria in check. There is less research on treatment with lactic acid bacteria than on treatment with antibiotics. Very few studies have looked at treatments with lactic acid bacteria on their own. They were generally used in combination with antibiotics. There is currently no scientific proof that vaginosis clears up any better when lactic acid bacteria treatments are used – either together with antibiotics or on their own. Little is known about the possible side effects of lactic acid bacteria.

Can vaginosis be treated during pregnancy?

If bacterial vaginosis develops during pregnancy, it can slightly increase the risk of the baby being born too early (preterm birth). There is also a higher risk of a late-term miscarriage or stillbirth (between week 13 and week 24 of pregnancy).

Researchers from the Cochrane Collaboration analyzed the results of studies on the pros and cons of treatment with antibiotics. They included a total of 21 studies involving nearly 8,000 pregnant women. They found that antibiotics can reduce the risk of late-term miscarriages:

• 2% of women who didn't take antibiotics had a late-term miscarriage.
• 0.3% of women who took antibiotics had a late-term miscarriage.

Antibiotics had no influence on the risk of preterm birth or the risk of the woman’s waters breaking too soon (premature rupture of membranes). About 2% of the women stopped the treatment due to side effects. There is no evidence that the antibiotics have any long-term side effects or harm the child when used to treat bacterial vaginosis.

Most of the women in the studies had no symptoms. The infection was discovered as a result of other tests they had during their pregnancy. If bacterial vaginosis is discovered during pregnancy because it is causing symptoms, it is usually treated too.

Sources

• Amaya-Guio J, Viveros-Carreño DA, Sierra-Barrios EM et al. Antibiotic treatment for the sexual partners of women with bacterial vaginosis. Cochrane Database Syst Rev 2016; (10): CD011701. [PMC free article: PMC6458027] [PubMed: 27696372]
• Brocklehurst P, Gordon A, Heatley E et al. Antibiotics for treating bacterial vaginosis in pregnancy. Cochrane Database Syst Rev 2013; (1): CD000262. [PMC free article: PMC11307253] [PubMed: 23440777]
• Chen R, Li R, Qing W et al. Probiotics are a good choice for the treatment of bacterial vaginosis: a meta-analysis of randomized controlled trial. Reprod Health 2022; 19(1): 137. [PMC free article: PMC9195231] [PubMed: 35698149]
• Huang H, Song L, Zhao W. Effects of probiotics for the treatment of bacterial vaginosis in adult women: a meta-analysis of randomized clinical trials. Arch Gynecol Obstet 2014; 289(6): 1225-1234. [PubMed: 24318276]
• Li C, Wang T, Li Y et al. Probiotics for the treatment of women with bacterial vaginosis: A systematic review and meta-analysis of randomized clinical trials. Eur J Pharmacol 2019; 864: 172660. [PubMed: 31562865]
• Ma S, Wang W, Su Y et al. Antibiotics therapy combined with probiotics administered intravaginally for the treatment of bacterial vaginosis: A systematic review and meta-analysis. Open Med (Wars) 2023; 18(1): 20230644. [PMC free article: PMC10505304] [PubMed: 37724125]
• Oduyebo OO, Anorlu RI, Ogunsola FT. The effects of antimicrobial therapy on bacterial vaginosis in non-pregnant women. Cochrane Database Syst Rev 2009; (3): CD006055. [PubMed: 19588379]
• Tan H, Fu Y, Yang C et al. Effects of metronidazole combined probiotics over metronidazole alone for the treatment of bacterial vaginosis: a meta-analysis of randomized clinical trials. Arch Gynecol Obstet 2017; 295(6): 1331-1339. [PubMed: 28386675]

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