If you’ve ever noticed faded spots or lightened patches on your underwear after doing laundry, you might have assumed the issue was due to detergent, bleach, or a problem with your washing machine. However, the true cause may actually have nothing to do with how you wash your clothes — and everything to do with your body’s natural chemistry.

Understanding the Science Behind the “Bleaching” Effect. According to Dr. Teresa Irwin, an OB-GYN known on TikTok as The Vag Doc, vaginal discharge naturally contains healthy bacteria, primarily from the lactobacilli family. These beneficial bacteria play a crucial role in maintaining the vagina’s health by creating a mildly acidic environment. This acidic pH helps prevent harmful bacteria and yeast from growing, protecting you from infections and irritation.

Interestingly, it is this very acidity — which is a sign of a healthy vaginal microbiome — that can sometimes cause the dye in underwear fabric to fade. When the discharge comes into contact with the fabric, the acid may strip away or alter the color, leaving behind pale or “bleached” spots. This reaction is especially noticeable on darker-colored underwear or materials that use less colorfast dye.

As Dr. Irwin explains, “If your vaginal discharge is more acidic, it can actually lighten the color of your underwear. It’s completely normal and usually nothing to worry about.”

Is This a Cause for Concern?

In most cases, no — it is not a problem at all. In fact, these faded areas are often a sign that your vaginal pH is balanced and functioning as it should. It means the healthy bacteria are present and active, which is a positive indicator of good vaginal health.

That being said, not every woman will notice this bleaching effect. It can vary from person to person and also depends on a number of other factors, including the type of underwear fabric, the quality and type of dye used, and how often the underwear is washed. Cotton fabrics, for example, may show bleaching more than synthetic materials, while certain dyes may be more vulnerable to fading.

When Should You Be Concerned?

While bleaching caused by natural vaginal acidity is normal, changes in your discharge could be a sign that something is wrong. You should contact a healthcare provider if you notice any of the following changes:

• A strong or unpleasant odor

• A significant change in color (such as green, gray, or yellow discharge)

• A thick, clumpy, or unusually watery texture

• Itching, burning, or irritation in the vaginal area

These symptoms could indicate a bacterial or yeast infection, or another medical issue that may require treatment.

Conclusion

So, if you find lightened or discolored spots on your underwear, don’t panic — it’s most likely a completely normal result of your body’s natural pH levels doing exactly what they’re supposed to do. It’s just a small reminder of the complex and intelligent ways your body works to keep you healthy every day.