Metronidazole {me-troe-ni-da-zole} gel is a type of antibiotic used to treat vaginal infections caused by harmful bacteria. Although this antibiotic gel is the traditional method of treating infections like bacterial vaginosis (BV), it is often less than 100% effective. Metronidazole is also known to cause side effects in some women and can react with other medications.
We're going to go over the benefits and side effects of metronidazole. We’ll also highlight a natural alternatives that can be used with, or instead of, metronidazole to treat once-off and recurring BV infections.
What is Metronidazole and How Is it Used?
Metronidazole is an antibiotic gel that is used intravaginally to treat bacterial vaginosis, which is a vaginal infection caused by the overgrowth of harmful bacteria. When prescribed for bacterial vaginosis, metronidazole is supplied with an applicator, which is used to insert the gel once or twice per day depending on the recommendation from your healthcare professional.
To insert the gel intravaginally, read the package instructions carefully and follow the steps outlined. These typically involve:
- Filling the provided applicator with gel as indicated
- Lying on your back with the knees bent and parted so you can reach your vagina
- Gently inserting the applicator into the vagina and pushing the plunger to release the gel
- Once the gel has been released into the vagina, the applicator can be washed with soap and warm water, and saved for later use.
Washing your hands after handling the applicator is vital to ensure the infection is not spread.
You also want to be careful not to get any metronidazole gel on your skin, eyes, or mouth. If this happens, wash with cool water and notify your healthcare professional.
Until your infection has cleared, refrain from sex. If you’ve taken too many doses of metronidazole gel, contact your healthcare professional for guidance on whether you should visit the emergency room.
What is Bacterial Vaginosis?
Bacterial vaginosis (BV) is a vaginal infection caused by an overgrowth of bacteria that naturally reside in the vagina. Most common in sexually active women aged 15-44, the exact cause of BV has not yet been determined by medical researchers. However, disruptions to healthy vaginal pH levels are believed to contribute.
Does Metronidazole Gel Successfully Treat BV?
Metronidazole gel is considered 70–80% effective at treating BV, with 15-30% of women known to suffer a recurring BV infection within 3-12 months. Because metronidazole is an antibiotic, it can also kill beneficial bacteria like lactobacilli and consequently cause a yeast infection that requires antifungal treatment. Or set the scene for BV to reoccur.
When BV is not successfully treated, and vaginal pH levels are not successfully re-balanced, BV can return numerous times. Having an untreated or recurring BV infection increases the risk of premature labor and contracting sexually transmitted diseases. Untreated BV can also cause a more serious condition called Pelvic Inflammatory Disease (PID), which can result in serious long-term side effects and infertility.
Potential Side Effects of Metronidazole
Although BV is most successfully treated with a combination of antibiotics and boric acid suppositories, taking metronidazole can cause side effects in some.
These can include:
- Allergic reactions on the skin, face, lips, tongue or throat
- Dizziness, confusion, or slurred speech
- Fever, neck pain, headache,
- Diarrhea, nausea, or vomiting
- Irregular heartbeat, chest pain, or trouble breathing
- Liver distress (pain in the right upper abdomen, a lightly-colored stool, dark yellow or brown urine, or yellowing skin or eyes)
- Numbness, tingling, or pain in the hands or feet
- Seizures
- Blurry vision, sudden eye pain, loss of vision
If you notice any of these side effects while taking metronidazole, stop taking the antibiotic and notify your healthcare professional immediately. They might advise you to continue taking the boric acid suppositories alone or prescribe another antibiotic.
Metronidazole Alternatives
Clindamycin
Clindamycin is a commonly prescribed alternative to metronidazole for bacterial infections. Available in both oral and topical forms, it is effective against a variety of bacterial infections, including those affecting the skin and reproductive system.
Boric Acid for BV
Boric acid is an effective alternative treatment for bacterial vaginosis (BV). Available in suppository form, it helps restore vaginal pH balance and reduces the overgrowth of harmful bacteria. Boric acid is typically used as a secondary treatment when standard antibiotics, like metronidazole, are ineffective or for recurrent cases of BV. Always consult your doctor before using boric acid, as it is not suitable for everyone.
Tinidazole
Similar to metronidazole, tinidazole is often used to treat infections like bacterial vaginosis and trichomoniasis. It works by killing bacteria and parasites but may have fewer side effects for some individuals.
Probiotics
Probiotics help restore the natural balance of bacteria in the body, particularly in cases of bacterial vaginosis or gut infections. While not a direct replacement for antibiotics, they can be a supportive treatment or preventive measure.
Secnidazole
Secnidazole is another antimicrobial agent used to treat bacterial vaginosis. It has a similar action to metronidazole but is often preferred for its single-dose regimen, making it more convenient for patients.
Herbal Remedies
Certain herbal remedies, like garlic and goldenseal, have antimicrobial properties and may be used as a natural alternative for mild bacterial infections. However, consult your healthcare provider before using herbal supplements for infections.
When Not to Take Metronidazole?
Depending on a patient’s overall health, there are some cases where metronidazole cannot be prescribed to treat BV. If you are breastfeeding, pregnant, or trying to get pregnant, metronidazole is not safe. It should also be avoided if you have Cockayne Syndrome, liver disease, a family history of blood diseases, have an allergy to preservatives or food dyes, or drink alcohol daily.
With Which Medications Does Metronidazole React?
When prescribed metronidazole to treat bacterial vaginosis or another bacterial infection, it’s important to inform your doctor of other medication you are taking to avoid an adverse reaction. It’s also wise to inform them of any dietary supplements, herbal remedies, non-prescription drugs, or recreational drugs that you take regularly.
The following list indicates common medications known to react with metronidazole but not all of them. Be sure to notify your doctor of any medication you take that is not on this list.
- Amiodarone
- Birth control pills
- Busulfan
- Carbamazepine
- Cimetidine
- Cisapride
- Cyclosporine
- Dofetilide
- Disulfiram
- Dronedarone
- Fluorouracil
- Phenobarbital
- Phenytoin
- Pimozide
- Quinidine
- Tacrolimus
- Thioridazine
- Vecuronium
- Warfarin
- Ziprasidone
What Treats Bacterial Vaginosis Successfully?
To treat BV successfully and prevent recurring infections, combining Boric Acid suppositories with antibiotics is recommended. Boric acid suppositories have been used to treat bacterial infections like BV for over a hundred years, and although modern research is still scarce, it is also incredibly positive.
For example, a 2009 study concluded that combining a full course of antibiotics with a full course of boric acid suppositories cured not only the current BV infection in 92% of women but prevented recurring infections too. A similar conclusion was reached after a 2020 study by the Journal of the American Sexually Transmitted Diseases Association.
Conclusion
Metronidazole gel is an antibiotic prescribed to treat vaginal infections caused by harmful bacteria like bacterial vaginosis. Although effective for many, metronidazole can cause side effects, and 30% of women are known to experience recurring BV infections after a full course.
Whereas, combining boric acid suppositories with antibiotics has been proven to cure BV infections, and recurring BV infections, in 92% of women without any adverse side effects.
If you suffer from recurring BV infections and antibiotics are not working, speak with your healthcare professional about taking boric acid suppositories long-term.
References
Medline Plus - Metronidazole Vaginal - https://medlineplus.gov/druginfo/meds/a617051.html
Centers for Disease Control and Prevention – Bacterial Vaginosis - https://www.cdc.gov/std/bv/stdfact-bacterial-vaginosis.htm
World Health Organisation – Bacterial Vaginosis - https://www.who.int/news-room/fact-sheets/detail/bacterial-vaginosis
National Library of Medicine - Vaginal pH Value for Clinical Diagnosis and Treatment of Common Vaginitis - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8618584/
Frontiers in Cellular and Infection Microbiology - The Female Vaginal Microbiome in Health and Bacterial Vaginosis - https://www.frontiersin.org/articles/10.3389/fcimb.2021.631972/full
Journal of The American Sexually Transmitted Diseases Association - Boric Acid Addition to Suppressive Antimicrobial Therapy for Recurrent Bacterial Vaginosis - https://journals.lww.com/stdjournal/Fulltext/2009/11000/Boric_Acid_Addition_to_Suppressive_Antimicrobial.13.aspx
National Library of Medicine - Clinicians’ use of Intravaginal Boric Acid Maintenance Therapy for Recurrent Vulvovaginal Candidiasis and Bacterial Vaginosis - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6878170/