Bacterial Vaginosis (BV) is one of the most common vaginal conditions globally, resulting from an imbalance in the natural vaginal flora. This condition involves the overgrowth of certain anaerobic bacteria, such as Gardnerella vaginalis, which replace the protective, acid-producing Lactobacilli species. The resulting disruption causes symptoms like thin, grayish discharge and a distinct fishy odor in symptomatic individuals. Confusion often centers on BV’s connection to sexual activity and the necessity of treating male sexual partners. This article clarifies why BV does not occur in men and details the current medical guidance regarding male partner involvement and management.
Understanding BV and Male Physiology
Bacterial Vaginosis is a state of microbial imbalance, or dysbiosis, specific to the environment of the vagina. The healthy vaginal ecosystem is maintained by a dominance of Lactobacillus bacteria, which produce lactic acid and hydrogen peroxide to keep the pH low, typically between 4.0 and 4.5. This acidic environment suppresses the growth of other organisms.
BV occurs when this protective Lactobacillus population declines, leading to a rise in pH and an overgrowth of various anaerobic bacteria, including Gardnerella vaginalis and Prevotella species. These bacteria often form a polymicrobial biofilm on the vaginal epithelial cells.
The male genitourinary tract, particularly the urethra and penile skin, does not possess the same micro-environmental conditions or hormonal influences that characterize the vaginal environment. Since the necessary physiological structures and delicate balance of flora are absent, men cannot spontaneously develop or contract Bacterial Vaginosis as it is diagnosed in women.
Addressing Male Symptoms and Colonization
While men do not contract BV, they can carry the bacteria associated with the condition on their genital skin and within the urethra. This state is known as colonization, which is distinct from an active infection that causes symptomatic disease. The presence of BV-associated bacteria, such as Gardnerella vaginalis, in male partners is often transient and typically causes no noticeable symptoms.
Colonization occurs because these bacteria can be transferred during sexual intercourse, meaning a male partner can harbor the same strain of bacteria found in his female partner’s vagina. This carriage, even without symptoms, is thought to play a role in the cycle of BV recurrence in the female partner. The bacteria can be reintroduced to the vagina after successful treatment, disrupting the newly restored balance of flora.
In rare instances, the bacteria associated with BV may contribute to mild, non-specific symptoms in men. These may include inflammation of the urethra, known as urethritis, or inflammation of the foreskin and head of the penis, called balanitis. When men present with such symptoms, a healthcare provider will diagnose and treat the specific condition causing the inflammation, which may involve targeting the BV-associated bacteria.
Treatment Protocols and Partner Management
The standard medical consensus, including guidelines from the Centers for Disease Control and Prevention, has historically advised against the routine treatment of male sexual partners of women with BV. This long-standing recommendation was based on previous randomized trials that failed to demonstrate that treating the male partner prevented BV recurrence in the female partner. The primary goal of treatment has always been to clear the infection and relieve symptoms in the individual with the vagina.
However, recent, high-quality clinical research has begun to challenge this traditional approach, particularly concerning recurrent BV. A landmark 2025 study found that concurrent treatment of the male partner significantly reduced the rate of BV recurrence in the female partner. The treatment protocol involved a combination of oral metronidazole and a topical clindamycin cream applied to the male partner’s penile skin.
This emerging evidence suggests that for couples struggling with frequent BV recurrence, treating the male partner may be a beneficial strategy to break the cycle of re-exposure and recurrence. The treatment for men is therefore usually nothing unless the female partner experiences frequent BV recurrence, or the man is symptomatic with urethritis or balanitis. Guidance for reducing recurrence risk for the female partner focuses on modifying behaviors that disrupt the vaginal microbiome. Avoiding douching, which can severely alter the natural flora, is strongly advised. Additionally, limiting the number of sexual partners and consistently using barrier methods like condoms can help to maintain a healthy microbial balance and reduce the risk of future episodes.