Vulvovaginitis: How to Tell Bacterial Vaginosis, Thrush and Trichomoniasis Apart and Treat Each One
Vulvovaginitis simply means inflammation of the vulva and vagina. It is not one condition but a label for several, and that is exactly why it is so often treated wrongly. Most women who notice itching or a change in discharge assume thrush and buy an antifungal. Often that is correct. Often it is not.
The most common cause of abnormal discharge in women of reproductive age is not thrush at all but bacterial vaginosis, which antifungals do nothing for. A sexually transmitted parasite, trichomonas, can look similar. After menopause, falling oestrogen causes soreness that mimics infection. And some women react to soaps, wipes or spermicides.
This guide explains how to tell the main causes apart, what treats each one, why bacterial vaginosis keeps coming back, and when you need a test rather than another self-treatment.
🔍 Which one is it?
| Bacterial vaginosis | Thrush | Trichomoniasis | Atrophic (after menopause) | |
|---|---|---|---|---|
| Discharge | Thin, grey-white, watery | Thick, white, like cottage cheese | Frothy, yellow-green, heavier | Scant, sometimes watery or blood-streaked |
| Smell | Fishy, worse after sex or a period | Little or none | Unpleasant | None |
| Itching | Usually mild or none | Intense | Often | Dryness and soreness more than itch |
| Soreness, pain with sex | Uncommon | Common | Common | Very common |
| Treated with | Metronidazole or clindamycin | Antifungals | Metronidazole, partner treated too | Vaginal oestrogen, moisturisers |
These patterns overlap, and two conditions can occur together. That is why a swab test is so useful when symptoms are new, unusual, keep returning, or did not clear with the first treatment.
🧫 Bacterial vaginosis: the most common cause
A healthy vagina is dominated by Lactobacillus bacteria, which keep it slightly acidic. In bacterial vaginosis, those protective bacteria fall away and a mixed group of others, including Gardnerella, overgrow. The acidity drops, and the chemicals these bacteria release produce the characteristic fishy smell, especially after sex, when semen makes the vagina less acidic still.
About half of women with bacterial vaginosis have no symptoms at all. It is not classed as a sexually transmitted infection in the usual sense, but it is linked to sex.
- 👫 A new sexual partner, or several partners
- 🚿 Douching or washing inside the vagina, and scented products
- 🚬 Smoking
- 🩸 A copper coil, which can make periods heavier
- 👩❤️👩 A female partner with bacterial vaginosis
💊 Treating bacterial vaginosis
| Treatment | Course | Notes |
|---|---|---|
| Metronidazole tablets | Twice daily for 7 days | The standard first choice. Can be taken in pregnancy |
| Metronidazole vaginal gel | Nightly for 5 days | Fewer stomach side effects |
| Clindamycin vaginal cream | Nightly for 7 days | Weakens latex condoms and diaphragms during and for several days after use |
| Clindamycin tablets | Twice daily for 7 days | An alternative when metronidazole cannot be used |
| Single large dose of metronidazole | One dose | Convenient, but recurrences are more common than with the 7-day course |
🍷 Metronidazole and alcohol. The traditional advice is to avoid alcohol during treatment and for 48 hours after the last dose, because the combination can cause flushing, nausea and a pounding heart. Research questions how common this reaction really is, but most pharmacists still recommend avoiding alcohol for that period. Metronidazole also leaves a metallic taste in the mouth, which is harmless.
Metronidazole is available as Flagyl (Metronidazol), and clindamycin tablets as Cleocin (Clindamycin). Antifungal thrush treatments will not clear bacterial vaginosis.
🔁 Why it keeps coming back
Bacterial vaginosis often returns: around half of women have another episode within a year. The reasons are still being studied. The bacteria form a protective film that treatment does not always clear, and sexual partners may carry the same bacteria back.
For frequent recurrences, doctors use several approaches:
- Suppressive treatment — metronidazole gel twice a week for several months after a full course
- Treating male partners — a recent large trial found that treating the male partner at the same time, with tablets and a cream applied to the penis, roughly halved the chance of recurrence. This is starting to change practice
- Removing triggers — stopping douching and scented products; reconsidering a copper coil
- Using condoms consistently, which reduces recurrence
Probiotics and boric acid are popular for recurrences. Evidence for probiotics is mixed. Boric acid pessaries are used for some stubborn cases under medical advice, but they are toxic if swallowed, must be kept away from children and are not used in pregnancy.
🤰 Bacterial vaginosis in pregnancy
In pregnancy, bacterial vaginosis is linked to a higher chance of early labour and late miscarriage. Pregnant women with symptoms should be tested and treated. Metronidazole tablets are considered suitable in pregnancy. Anyone pregnant with new discharge or odour should mention it to the midwife rather than self-treat.
🦠 Trichomoniasis
Trichomoniasis is caused by a tiny parasite, Trichomonas vaginalis, passed on during sex. It is one of the most common sexually transmitted infections worldwide, and many people carry it without symptoms, especially men.
In women it can cause a heavy, frothy, yellow-green discharge with an unpleasant smell, itching and soreness, and pain on passing urine or during sex. Men may notice discharge or burning, but most notice nothing.
| Step | What it involves |
|---|---|
| Test | A vaginal swab or urine test. Testing for other infections, such as chlamydia, at the same time is sensible |
| Treatment for women | Metronidazole twice daily for 7 days, which is more effective than a single dose |
| Treatment for men | Usually a single larger dose of metronidazole |
| Partners | All current partners are treated at the same time, even without symptoms |
| Sex | Avoid until both partners have finished treatment and symptoms have gone |
| Retest | Around three months later, because reinfection is common |
If discharge comes with pelvic pain, bleeding after sex or burning, chlamydia also needs to be excluded. Our guide to chlamydia treatment covers it.
🍄 Thrush, briefly
Vaginal thrush is caused by Candida yeast. It produces intense itching, soreness and a thick white discharge without much smell. It is treated with antifungal pessaries, creams or a single tablet of fluconazole, available as Fluconaz (Fluconazole). Why self-treatment so often misses, and what to do about recurrent thrush, is covered in detail in our guide to vaginal thrush.
🌸 After menopause: atrophic vaginitis
As oestrogen falls after menopause, the vaginal lining becomes thinner, drier and more easily irritated. The result is soreness, burning, pain during sex, itching, sometimes light bleeding, and often repeated urinary infections. Doctors now call this the genitourinary syndrome of menopause. It is extremely common and, unlike hot flushes, it does not fade with time.
It is also very treatable. Low-dose vaginal oestrogen restores the lining, relieves symptoms and reduces urinary infections, with very little absorbed into the bloodstream. Non-hormonal vaginal moisturisers used regularly, and lubricants during sex, help too. Vaginal oestrogen is available as Vagifem (Estradiol). Early or premature menopause is covered in our guide to early menopause.
🔴 Bleeding after menopause always needs checking. Even if dryness seems the obvious cause, any vaginal bleeding after periods have stopped for a year should be assessed by a doctor.
🧼 Irritation and allergy
Not every case is an infection. Soaps, shower gels, bubble baths, scented wipes, douches, feminine sprays, spermicides, latex and even some washing powders can inflame the vulva. The skin becomes red, itchy and sore without an unusual discharge. Treatment is simply removing the cause: wash with water or a plain emollient, wear cotton underwear, avoid tight synthetic clothing, and stop anything scented.
Persistent vulval itching that does not respond, especially with white, thickened or shiny skin, can be a skin condition such as lichen sclerosus. It needs examination and specific treatment.
👧 Vulvovaginitis in girls
Before puberty, the vulval skin is thin and there is no protective oestrogen, so irritation is common. The usual causes are simple: bubble baths and soaps, wiping from back to front, tight clothing, and staying in wet swimwear. Itching mainly at night, around the bottom as well as the vulva, may be threadworms, treated with mebendazole, which is available as Mebenza Chewable (Mebendazole), with the whole household treated together.
Thrush is uncommon in girls who are out of nappies, so antifungal creams are rarely the answer. A doctor should see a girl with discharge, bleeding, persistent symptoms, or any concern about how the symptoms arose.
🛡️ Everyday prevention
- Do not wash inside the vagina
- It cleans itself. Douching removes protective bacteria and raises the risk of bacterial vaginosis.
- Water or a plain emollient for the vulva
- Skip scented soaps, gels, wipes and sprays.
- Cotton underwear, not too tight
- Change out of wet swimwear and sweaty gym clothes promptly.
- Condoms
- Reduce trichomoniasis and other infections and lower bacterial vaginosis recurrence.
- Do not reach for antifungals automatically
- If the smell is fishy and itch is mild, thrush treatment is likely to be the wrong choice.
📞 When to see a doctor
- First episode of unusual discharge or odour, or unsure what it is
- Symptoms not cleared by one course of treatment
- Four or more episodes a year
- Pregnancy with new discharge, odour or itching
- Pelvic pain, fever, or bleeding after sex
- A new partner or possible exposure to a sexually transmitted infection
- Any bleeding after menopause
- A girl with discharge or persistent symptoms
❓ Frequently asked questions
How do I tell BV from a yeast infection?
Bacterial vaginosis usually causes thin grey-white discharge with a fishy smell, often worse after sex, and little itching. Thrush causes intense itching and soreness with thick white discharge and little smell. They need different treatments, so if you are unsure, a swab test is worthwhile.
What causes a fishy vaginal smell?
Most often bacterial vaginosis, where protective lactobacilli are replaced by other bacteria that release fishy-smelling chemicals. It is often noticed after sex or a period. Trichomoniasis can also cause an unpleasant smell.
What is the best treatment for bacterial vaginosis?
Metronidazole tablets twice daily for 7 days are the standard first choice. Metronidazole gel for 5 days or clindamycin cream for 7 days are alternatives. A single large dose of metronidazole is more convenient but followed by more recurrences.
Can I drink alcohol while taking metronidazole?
The usual advice is to avoid alcohol during treatment and for 48 hours afterwards, because the combination can cause flushing, nausea and palpitations. How often this happens is debated, but avoiding alcohol for that period is still recommended.
Why does my BV keep coming back?
Around half of women have another episode within a year. The bacteria form a protective film that treatment may not fully clear, and partners can carry them back. Suppressive treatment, treating the male partner, condoms and avoiding douching all reduce recurrences.
Does my partner need treatment for BV?
Traditionally male partners were not treated, but a recent large trial found that treating them at the same time roughly halved recurrences. Discuss it with your doctor, especially if bacterial vaginosis keeps returning. For trichomoniasis, partners must always be treated.
Is trichomoniasis a sexually transmitted infection?
Yes. It is caused by a parasite passed on during sex. It is treated with metronidazole, all partners are treated at the same time, and sex is avoided until both have finished treatment. A retest around three months later is advised.
Is bacterial vaginosis dangerous in pregnancy?
It is linked to a higher chance of early labour and late miscarriage, so pregnant women with symptoms should be tested and treated. Metronidazole tablets are considered suitable in pregnancy.
What helps vaginal dryness and soreness after menopause?
Low-dose vaginal oestrogen is the most effective treatment and also reduces urinary infections. Non-hormonal vaginal moisturisers and lubricants help as well. Any bleeding after menopause should be checked by a doctor.
What causes vulvovaginitis in young girls?
Usually irritation from soaps and bubble baths, wiping back to front, tight clothing or wet swimwear. Night-time itching around the bottom may be threadworms. Thrush is uncommon in girls out of nappies. Persistent symptoms, discharge or bleeding need a doctor.
📑 Sources and editorial
- National guidelines on the management of bacterial vaginosis and trichomoniasis
- Sexually transmitted infections treatment guidelines, including the seven-day metronidazole regimen for trichomoniasis in women
- Randomised trial of male partner treatment to prevent bacterial vaginosis recurrence
- Guidance on genitourinary syndrome of menopause and vaginal oestrogen
- Guidance on vulvovaginitis in prepubertal girls
- Reviews of metronidazole and alcohol interaction
- Related reading: vaginal thrush, chlamydia treatment, early menopause
- Related products: Flagyl (Metronidazol), Fluconaz (Fluconazole), Vagifem (Estradiol)
- RXshop Editorial Team — reviewed by Anita Sharma, MD, OB-GYN
Medical Disclaimer: The information in this article is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek guidance from a qualified healthcare provider with any questions you may have regarding a medical condition, and before starting, stopping or changing any medication.