Bad vaginal odor can be a sign of infection with bacteria or a parasite. These infections are common in women and may resolve on their own or may require antibiotic treatment.

In every woman, the vagina has a peculiar smell. This may vary in a normal way throughout the menstrual cycle and become, for example, slightly more acidic during menstruation. A small difference in smell is therefore not always an alarming sign. This is why it is important to learn to know its natural scent. However, if the smell is very different and unpleasant, it may be a sign of an infection (vaginosis).

Remember that the vagina is naturally home to many microorganisms that make up what is called the vaginal flora. This is mainly made up of a bacterium called Döderlein’s bacillus or lactobacillus. It maintains an acidic environment in the vagina and thus helps to protect it against infections. Any change in the balance of these microorganisms can affect vaginal odor.

The two most common causes of an abnormal odor from the vagina are:

• a bacterial infection (or bacterial vaginosis). Most often it is due to the Gardnerella bacteria vaginalis. This is naturally present in the vagina, but in some cases it can multiply abnormally and outweigh other bacteria. It produces a so-called “rotten fish” odor;
• a parasitic infection by “trichomonas vaginalis (Trichomoniasis). It is a sexually transmitted infection (STI), which is easily treated.

Abnormal vaginal odor is not the only characteristic symptom of these infections. Itching, a burning sensation, local pain, redness or abnormal vaginal discharge (leucorrhea) may accompany it.

Yeast or Chlamydia and Neisseria infections gonorrhoeae (gonorrhea) usually do not cause vaginal odor.

Certain illnesses or behaviors can promote infections. Let us quote for example:

• poor hygiene or, on the contrary, excessive hygiene;
• the stress ;
• antibiotic treatment;
• a rectovaginal fistula (an abnormal opening between the rectum and the vagina that causes faeces to flow into the vagina);
• cancer of the cervix;
• a cancer of the vagina.

If the infection that causes bad vaginal odor is not treated, it may get worse and also increase the risk of getting other infections. Trichomoniasis, for example, increases the risk of contracting or transmitting the AIDS virus (HIV).

Bacterial vaginosis during pregnancy increases the risk of premature labor.

In the event of an abnormal vaginal odor, the doctor will take a sample to determine whether the infection is due to a bacteria or a parasite and to suggest an appropriate antibiotic treatment. In the event of trichomoniasis, he may decide to treat the sexual partner as well.

Infections are more common in sexually active women, and multiple partners increase the risk of developing vaginosis.

Good personal hygiene is important to limit the risk of infection. But this does not require any particular technique, your vagina is self-cleaning. Therefore, prefer the use of a mild soap on the pubic hair and the outside of the vulva. Avoid excessive rubbing or douching (introducing water with or without soap into the vagina). Special cleaning products should also be avoided, as these can alter the natural balance of microorganisms in the vagina and promote infections. Shaving or intimate waxing are also risk factors, because the hairs have a protective role.