Finding bleach patches in your underwear can be puzzling. While it’s commonly associated with cleaning accidents, there are several potential causes for this issue, including accidental bleach exposure, personal care products, and even perspiration.

1. **Accidental Exposure to Bleach**
Bleach spills during cleaning or laundry can cause small amounts to come in contact with your underwear, leading to bleach stains. Be careful when handling bleach and store it safely away from clothing.

2. **Personal Care Products**
Certain skin, hair, and hygiene products like acne treatments containing hydrogen peroxide or benzoyl peroxide can cause bleach-like stains on fabric. These chemicals can unexpectedly bleach your clothing when they make contact.