# What Is Bacterial Vaginosis? Symptoms, Causes and Vaginal Odour

- Page: https://www.carewithki.com/en/discover/what-is-bacterial-vaginosis
- Published: 28 October 2026
- Topics: Vaginal Health, Infection
- Publisher: care with .ki (content principles: https://www.carewithki.com/en/editorial-policy)

![What Is Bacterial Vaginosis? Symptoms, Causes and Vaginal Odour](https://www.carewithki.com/blog/en/bakteriyel-vajinozis-nedir.jpg)

> Bacterial vaginosis is a common condition caused by an imbalance of vaginal bacteria and is the most common cause of abnormal discharge (CDC). Its typical sign is thin, watery, grey-white discharge with a fishy smell, particularly after sex. Half of women have no symptoms. It is not classed as a sexually transmitted infection, but sex can trigger it (NHS).

Bacterial vaginosis is a common condition caused by an imbalance of vaginal bacteria and is the most common cause of abnormal discharge (CDC). Its typical sign is thin, watery, grey-white discharge with a fishy smell, particularly after sex. Half of women have no symptoms. It is not classed as a sexually transmitted infection, but sex can trigger it (NHS).

**In brief:**

- Bacterial vaginosis does not usually cause itching, an important difference from a yeast infection.
- A doctor diagnoses it and plans treatment, usually with antibiotics.
- It can recur often; scented products and douching increase the risk.
- If your discharge changes during pregnancy, always tell your doctor or midwife.

## What is bacterial vaginosis?

In a healthy vagina, ‘good’ bacteria called lactobacilli predominate and keep the environment mildly acidic. In bacterial vaginosis, this balance is disrupted and other bacteria replace lactobacilli (CDC, NHS). According to the CDC, bacterial vaginosis is the most common cause of [abnormal vaginal discharge](https://www.carewithki.com/en/discover/normal-vaginal-discharge) worldwide. A US national survey found no symptoms in most women with bacterial vaginosis.

For vaginal flora balance and the role of lactobacilli, see [Vaginal Probiotics](https://www.carewithki.com/en/discover/vaginal-probiotics).

## What are the symptoms?

According to the NHS:

- A strong, fishy smell, especially after sex
- Thin, watery, grey-white discharge
- It does not usually cause itching or soreness
Half of women have no symptoms at all (NHS).

## What causes vaginal odour?

Healthy discharge has no strong or unpleasant smell (NHS). Common causes of odour include:

- **Bacterial vaginosis:** A fishy smell, especially after sex (NHS).
- **Trichomoniasis:** Yellow-green, frothy discharge that may smell fishy; it is sexually transmitted (NHS).
- **Scented products and douching:** Perfumed products used to mask odour, and washing inside the vagina, can upset the balance and increase the risk of bacterial vaginosis (NHS).
Trying to mask the smell with perfumed products does not solve the problem and may make it worse. See a doctor if you notice a persistent or changing smell.

## Bacterial vaginosis or a yeast infection?

Bacterial vaginosis versus vaginal yeast infection: BV causes thin, grey-white, fishy-smelling discharge, usually without itching; yeast infection causes thick white, cottage-cheese-like, odourless discharge, often with itching

These two conditions are often confused. This comparison is intended to help you describe symptoms to a doctor, not to diagnose yourself:

|  | Bacterial vaginosis | Vaginal yeast infection |
| --- | --- | --- |
| Discharge | Grey-white, thin, watery | White, thick, like cottage cheese |
| Smell | Distinctly fishy | Usually odourless |
| Itching | Usually absent | Common |

Source: NHS. For more about yeast infections, see [What Is a Vaginal Yeast Infection?](https://www.carewithki.com/en/discover/vaginal-yeast-infection).

## What causes it, and what increases the risk?

The exact cause is not fully understood. According to the NHS, risk increases with:

- Being sexually active, although it can also occur in women who have never had sex
- A change of partner
- Use of an intrauterine device (IUD)
- Using scented products in or around the vagina

## Why does it matter?

Bacterial vaginosis often does not cause a serious problem. However:

- **In pregnancy:** It may slightly increase the risk of premature birth and miscarriage, though most pregnancies are unaffected (NHS). The CDC recommends treating all pregnant women who have symptoms.
- **Infection risk:** Bacterial vaginosis may increase the risk of sexually transmitted infections (NHS, CDC).

## How is it diagnosed and treated?

A doctor makes the diagnosis. CDC diagnostic criteria include the appearance of discharge, vaginal pH above 4.5, confirmation of odour by a test and typical cells seen under a microscope; at least three criteria must be present together.

Treatment usually involves antibiotic tablets, gel or cream prescribed by a doctor (NHS). The CDC's 2021 guideline does not recommend routine treatment of a male partner; a female partner may also need treatment (NHS). However, a 2025 study in monogamous couples found that when the male partner also received oral and topical treatment, recurrence within 12 weeks was 35%, compared with 63% when only the woman was treated (Vodstrcil et al., 2025). This approach has not yet been incorporated into guidelines.

## What can you do to help prevent it coming back?

NHS advice to reduce recurrence: wash the genital area with water and plain soap, shower instead of bathing; avoid scented products, vaginal deodorants and douching, do not add antiseptic to bathwater, do not wash underwear with harsh detergents, do not smoke

Bacterial vaginosis often recurs, usually within a few months (NHS). If it happens more than four times a year, a doctor may recommend preventive treatment for several months. NHS advice:

**Do:**

- Wash the genital area with water and plain soap.
- Shower instead of taking baths.
**Do not:**

- Do not use scented products, vaginal deodorants, internal washing products or vaginal douches.
- Do not add antiseptic liquid to bathwater.
- Do not wash underwear with harsh detergents.
- Do not smoke.

## When should you see a doctor?

- If you think you may have bacterial vaginosis; it is not an emergency, but treatment is needed (NHS)
- If you are pregnant and your discharge has changed (NHS)
- If symptoms return after treatment
- If you have other symptoms such as itching, pain, bleeding or fever

## Frequently asked

### Is bacterial vaginosis sexually transmitted?

It is not classed as a sexually transmitted infection, but sex can trigger or pass it on (NHS).

### Can bacterial vaginosis go away on its own?

Sometimes it resolves without treatment. However, treatment helps reduce some risks associated with bacterial vaginosis, including premature birth in pregnancy and acquiring other sexually transmitted infections (CDC). See a doctor if you have symptoms or are pregnant; a doctor plans treatment.

### Does my partner also need treatment?

The CDC's 2021 guideline does not recommend routine treatment of a male partner; a female partner may also need treatment (NHS). A study published in 2025 found that treating the male partner too may reduce recurrence (Vodstrcil et al., 2025); discuss this with your doctor if it keeps returning.

## References

- NHS. Bacterial vaginosis. Last reviewed 19 June 2026. https://www.nhs.uk/conditions/bacterial-vaginosis/
- Centers for Disease Control and Prevention (CDC). Bacterial vaginosis. Sexually Transmitted Infections Treatment Guidelines, 2021. https://www.cdc.gov/std/treatment-guidelines/bv.htm
- NHS. Vaginal discharge. Last reviewed 15 February 2024. https://www.nhs.uk/symptoms/vaginal-discharge/
- NHS. Trichomoniasis. Last reviewed 16 July 2025. https://www.nhs.uk/conditions/trichomoniasis/
- Vodstrcil LA, Plummer EL, Fairley CK et al. Male-partner treatment to prevent recurrence of bacterial vaginosis. New England Journal of Medicine, 2025;392(10):947–957. [doi:10.1056/NEJMoa2405404](https://doi.org/10.1056/NEJMoa2405404)
- Centers for Disease Control and Prevention (CDC). About Bacterial Vaginosis (BV). 11 December 2023. https://www.cdc.gov/bacterial-vaginosis/about/index.html

_This article is general information; it is not a diagnosis or treatment recommendation._