What Causes Secretions to Have a Fishy Odor?

Do not ignore vaginal discharge that emits a fishy or foul odor when smelled, as normal vaginal discharge is typically colorless and odorless. A fishy odor strongly indicates an abnormality in the discharge. So, what causes vaginal discharge to develop a fishy odor? Below, we address this question.

What Causes Vaginal Discharge to Emit a Fishy Odor?

A fishy odor in vaginal discharge may indicate bacterial vaginosis (BV), a common type of vaginitis among women. BV results from an imbalance in the normal vaginal flora, leading to excessive proliferation of anaerobic bacteria. Its primary clinical manifestations include increased vaginal discharge, which appears grayish-white and is accompanied by a distinct fishy odor. In contrast, normal (physiological) vaginal discharge is white, thin and mucoid—or clear and egg-white-like—in consistency, relatively viscous, scant in volume, and odorless. To confirm whether bacterial vaginosis is responsible for the fishy-smelling discharge, a routine vaginal discharge examination can be performed. If “clue cells” are detected on microscopy, bacterial vaginosis is likely present, and appropriate treatment should follow—typically involving oral metronidazole combined with topical therapy. Additionally, sexual intercourse should be avoided during treatment, and partners should be treated concurrently.

Knowledge Extension: Classification of Abnormal Vaginal Discharge

1. Fishy Odor

Vaginitis caused by certain anaerobic bacterial infections, trichomoniasis, or infection with Haemophilus vaginalis often produces vaginal discharge with a fishy odor.

2. Foul (Putrid) Odor

A foul or putrid odor in vaginal discharge frequently signals severe genital tract infection or malignancy—for example, gynecologic cancers, severe endometritis, or advanced cervical erosion. In particular, elderly women presenting with foul-smelling, bright red vaginal discharge should be evaluated urgently, as this may be an early sign of malignancy.

The above outlines the potential causes of fishy-smelling vaginal discharge. We hope this information proves helpful to you.