Salud vaginal y vulvar
Bacterial vaginosis (BV)
Revisado: 4 de octubre de 2026
Solo en inglés por ahoraBV is a common change in the balance of bacteria in the vagina. It can cause thin, fishy-smelling discharge, and it is treated with antibiotics.
What BV is
Bacterial vaginosis (BV) happens when the natural balance of bacteria in the vagina changes and some kinds grow too much. It is the most common vaginal condition in women aged 15 to 44, and a common cause of unusual discharge. BV is not classed as a sexually transmitted infection (STI). Sex can trigger it or pass it on, but people who have never had sex can get it too.
Signs of BV
The main sign is discharge with a strong fishy smell, which is often stronger after sex. The discharge may also change colour and texture, becoming thin, watery and greyish-white. Some people have itching, pain or burning in or around the vagina, or burning when they pee. About half of women with BV have no symptoms at all.
What raises the chance of BV
Doctors do not fully understand how sex is linked to BV. BV is more common if you are sexually active, have a new partner or more than one partner, or have sex without condoms. Washing inside the vagina (douching), using perfumed products in or around the vagina, and having an IUD (coil) are also linked to BV. Not smoking may help lower your chance of getting it.
Treatment and why it matters
BV is treated with antibiotics. These can be tablets, or a gel or cream. If your partner has a vagina, they may need treatment too. Treating BV matters because it is linked to a higher chance of getting HIV and other STIs. During pregnancy there is a small chance that BV can lead to problems such as an early (premature) birth or miscarriage.
Stopping it coming back
BV often comes back, usually within a few months. To lower the chance, wash your genital area with water and plain soap, and have showers rather than baths. Avoid perfumed soap, bubble bath, shower gel and antiseptic liquids in the bath. Do not use vaginal washes, deodorants or douches, and avoid strong detergents for your underwear. Using a condom every time you have sex can also help.
When to see a doctor or nurse
See a doctor, nurse or sexual health clinic if you think you have BV, and tell them if you are pregnant. Go back if it keeps returning (more than 4 times in a year), as other treatment may help. Get checked too if your discharge is green, yellow or frothy, or comes with pelvic pain or bleeding. These can be signs of an STI that needs different treatment.
This is general information, not a diagnosis. If you notice unusual discharge or a fishy smell, see a doctor, nurse or sexual health clinic.