What are common reasons for vaginal discharge having an odor?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Vaginal odor most commonly results from bacterial vaginosis (BV), an infection in which bacteria produce trimethylamine, creating a distinct fishy smell. Other frequent causes include vaginitis (such as yeast infections or trichomoniasis), hormonal shifts, poor ventilation, retained tampons, or disruptions to the vagina's natural bacterial balance. While mild odor changes can be normal, persistent, strong, or unusual smells—especially when paired with itching, discharge, or irritation—may signal an underlying condition that needs attention.

Because symptoms of BV, yeast infections, and other causes can overlap, self-diagnosing is unreliable and delaying care can allow infections to worsen. A quick, free, and private symptom check can help you understand what may be causing your symptoms and guide your next steps—whether that's home care, seeing a clinician, or seeking urgent evaluation. It takes just a few minutes and could save you days of worry.

Reviewed for medical accuracy: 07/15/2026

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Explanation

There are a few common reasons why vaginal discharge might have an odor. One major cause is bacterial vaginosis. In this condition, the normal bacteria balance in the vagina change and a substance called trimethylamine is produced, giving the discharge a fishy smell. Some women may also experience similar odors when they have other types of vaginitis (inflammation of the vagina) where changes in the bacteria and pH can occur. These infections usually cause changes in the look, smell, or amount of discharge. Sometimes, the odor might be stronger if there is an overgrowth of certain bacteria. It is important to notice other symptoms too, like itching, burning, or discomfort, as they can indicate an infection. If you're experiencing unusual discharge or odor along with other symptoms, you can use Ubie's free AI symptom checker to help understand what might be causing your symptoms, but it's also wise to talk with a healthcare provider to get the right tests and treatment if needed.

(References)

Brand JM, Galask RP. Trimethylamine: the substance mainly responsible for the fishy odor often associated with bacterial vaginosis. Obstet Gynecol. 1986 Nov;68(5):682-5. PMID: 3763085.
Paladine HL, Desai UA. Vaginitis: Diagnosis and Treatment. Am Fam Physician. 2018 Mar 1;97(5):321-329. PMID: 29671516.
Dorjey Y, Wangmo D, Tshomo D. Assessment of excessive vaginal discharge among women who presented to Phuentsholing General Hospital: A hospital-based study. Health Sci Rep. 2022 Sep 1;5(5):e793. doi: 10.1002/hsr2.793. PMID: 36090622; PMCID: PMC9436175.

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