Bacterial Vaginosis vs Thrush: How to Tell the Difference
Bacterial vaginosis (BV) and vaginal thrush are two of the most common causes of vaginal discomfort and unusual discharge in people with vaginas. Although they can cause similar symptoms—such as discharge and odour — they have different causes, risk factors, and treatments. Understanding these differences can help you recognize when to seek care and how to manage or prevent recurrences.
What Is Bacterial Vaginosis?
Bacterial vaginosis occurs when the balance of “good” and “bad” bacteria in the vagina is disrupted. Normally, lactobacilli bacteria keep the environment slightly acidic, which inhibits the overgrowth of other organisms. In BV, lactobacilli levels drop and other anaerobic bacteria multiply, leading to symptoms. BV is not classified as a sexually transmitted infection (STI), though sexual activity can trigger it, and having BV can increase your risk of acquiring other STIs.
BV affects up to one-third of people with vaginas at some point in their lives. While half of those with BV experience no symptoms, those who do often report a thin, greyish-white discharge with a characteristic “fishy” odour, especially after intercourse. In pregnancy, untreated BV has been associated with complications such as preterm birth, so it’s important to seek medical advice if you suspect BV while pregnant.
What Is Vaginal Thrush?
Vaginal thrush, also known as vulvovaginal candidiasis — is a yeast infection caused by the fungus Candida, most often Candida albicans. Candida normally lives in small numbers on the skin and in mucous membranes (mouth, gut, vagina) without causing harm. Candida can overgrow and cause symptoms, when the balance between yeast and bacteria is disturbed - for example, by antibiotics, hormonal changes, or immune suppression. Thrush is not an STI, although it can sometimes be passed through sexual contact.
Almost three-quarters of people with vaginas will experience thrush at least once, and about 1 in 20 will have four or more episodes in a year (recurrent thrush). Symptoms typically include intense itching and soreness around the vulva, a thick “cottage cheese”–like discharge without a strong odour, and discomfort or burning when urinating or during sex.
Professional GP advice, anytime, anywhere
Diagnosis
When you go to a clinic or doctor’s office with symptoms, here’s what usually happens:
Talking About Your Symptoms: The nurse or doctor will ask you a few questions about what you’re feeling — things like when your symptoms started, what your discharge looks or smells like, and any recent changes in your health or activities.
A Simple Exam: You’ll lie back on an exam table (similar to a Pap smear). Using a smooth, gloved instrument called a speculum, the provider gently opens the vagina so they can see inside and check for redness, swelling, or other signs of infection.
Collecting a Sample: A small, soft swab is used to take a little bit of the discharge (the fluid coming from your vagina). It’s quick and usually doesn’t hurt—maybe just a slight pressure.
Testing the Sample: Once the results come back (often within a day or two) your provider can explain which condition you have and recommend the right treatment.
For Bacterial Vaginosis (BV): The lab looks for a mix of clues that tell us BV is likely.
For Thrush (Yeast Infection): The lab checks the sample under a microscope for yeast cells (called Candida). They might also try to grow the yeast on a special nutrient plate (a “culture”) to be extra sure.
Treatment Options
Bacterial Vaginosis
The first-line treatments are oral metronidazole or clindamycin, or metronidazole gel applied intravaginally. Always complete the full course, even if symptoms improve earlier.
Vaginal Thrush
Antifungal medications: Options include over-the-counter clotrimazole or miconazole creams, pessaries, or single-dose oral fluconazole. Prescription regimens may be needed for recurrent cases.
Recurrent thrush protocol: For frequent episodes (≥4/year), a typical strategy is an initial intensive phase of daily antifungal for 10–14 days, followed by a weekly maintenance dose for six months.
Prevention Tips
Maintain healthy flora: Avoid douching and perfumed products; use mild, unscented soaps around the vulva only.
Wear breathable fabrics: Choose cotton underwear and avoid excessively tight clothing.
Safe sexual practices: Use condoms to reduce bacterial shifts and minimize the risk of BV recurrence.
Probiotics?: Some evidence suggests that oral or vaginal probiotics containing Lactobacillus species may help restore healthy flora, though more research is needed.
Antibiotic stewardship: If you must take antibiotics, consider taking probiotics afterward to reduce thrush risk.
When to See a Healthcare Provider
Seek medical attention if you experience:
Unusual discharge with a strong odour or colour change
Severe itching, burning, or pain around the vagina
Symptoms that do not improve after a full course of treatment
Recurrent episodes (four or more per year)
Symptoms during pregnancy, as complications can arise from untreated BV or thrush
Prompt diagnosis and appropriate treatment can relieve discomfort and reduce the risk of complications such as pelvic inflammatory disease, increased susceptibility to STIs, or pregnancy-related issues.
By understanding the distinct features of bacterial vaginosis and vaginal thrush — what causes them, how they present, and how they’re treated, you can better advocate for your own reproductive health and seek timely care. Regular check-ups, open communication with healthcare providers, and lifestyle measures to support a healthy vaginal environment are your best defences against these common yet manageable conditions.
