Bacterial Vaginosis (BV) is a common condition that occurs when the normal balance of bacteria in the vagina is disrupted. The healthy vaginal environment is typically dominated by protective Lactobacillus bacteria, but BV involves an overgrowth of other, anaerobic bacteria. Intrauterine Devices (IUDs) are a highly effective form of long-acting reversible contraception placed directly into the uterus. Because any foreign object can potentially affect local biology, users often question whether an IUD increases the likelihood of developing BV.
IUD Type and the Risk of Bacterial Vaginosis
The risk of developing BV while using an IUD depends largely on the type of device chosen. IUDs are broadly categorized into copper and hormonal types. Studies show that copper IUDs may be associated with a slightly higher risk of BV compared to hormonal IUDs or no contraception at all. One analysis found that copper IUD users experienced a 1.28-fold, or 28%, higher risk of BV compared to women using no contraception or another non-hormonal method. This elevated risk has been observed to persist for up to 18 months after insertion.
In contrast, hormonal IUDs have not shown the same clear association with an increased long-term BV risk. Some research suggests that hormonal IUDs may even have a neutral or potentially protective effect on vaginal flora. The localized release of progestin appears to influence the vaginal environment differently than the presence of copper. While the IUD insertion process carries a transient, short-term risk of infection, the long-term difference in BV risk is primarily distinguished by the device’s composition.
How IUDs May Influence Vaginal Flora
The mechanisms by which IUDs influence the vaginal microbiome involve both physical and biological factors. The presence of a foreign object, such as the IUD and its string, can introduce a surface for bacterial colonization. This physical presence may facilitate the formation of a biofilm, which is a structured community of bacteria that adheres to a surface and is resistant to antibiotics and the immune system. The bacteria associated with BV are known to form these biofilms.
Another contributing factor, particularly with the copper IUD, is the potential for increased or prolonged menstrual bleeding. Menstrual blood has a higher pH than the normal acidic vaginal environment, and the presence of blood can temporarily suppress the growth of protective Lactobacillus bacteria. This temporary shift in pH can create a more favorable environment for the anaerobic bacteria that cause BV. Furthermore, the presence of copper itself might encourage the overgrowth of certain bacteria, as some species like E. coli have been shown to feed on copper.
For hormonal IUDs, the localized release of progestin can thicken cervical mucus, which is generally considered a protective factor against ascending infections. While this hormone may slightly change the vaginal environment, the overall long-term effect on the vaginal flora seems to be less disruptive than the mechanical and bleeding effects associated with the copper IUD.
Identifying Symptoms and Addressing BV
Recognizing the symptoms of BV is the first step toward seeking appropriate treatment. The most common sign of BV is an unusual vaginal discharge that is typically thin, watery, and grayish-white. Many people also notice a distinct, strong odor often described as “fishy,” which may become more noticeable after intercourse. However, up to 84% of individuals with BV may not experience any noticeable symptoms at all.
A healthcare provider must confirm the diagnosis, as BV symptoms can be similar to other vaginal infections. Standard medical treatment for BV involves a course of antibiotics, such as metronidazole or clindamycin, taken orally or applied as a gel or cream inside the vagina. If you have an IUD and are diagnosed with BV, the device does not usually need to be removed for the infection to be treated successfully.
If BV becomes recurrent—meaning it returns shortly after treatment—it is important to discuss this with a healthcare provider. For those with a copper IUD experiencing repeated BV, the device may be a contributing factor, and alternatives like switching to a hormonal IUD or another contraceptive method may be considered. In cases of persistent infection, a healthcare professional may suggest removing the IUD to see if the vaginal flora can successfully re-establish a healthy balance.