It's not just about washing either

Meaning that even if you dry your bra well, mould can grow if you're generally a sweaty person and your bra doesn't handle sweat well. Thick materials trap moisture from your sweat and mould can grow from the long hours you spend wearing a bra.

How do you get mold out of bras?

Combine lemon juice and salt to make a thick paste and rub it into mildewed-infested areas on clothing. Quickly dry affected garments in direct sunlight, then, if the stain is still there, do it all again. Repeat the process until the mildew is gone. Water and vinegar is another simple way to rid clothing of mildew.

Why is my bra turning black?

There are other more common reasons of staining on bras: deodorants that contain aluminum may cause discoloration when mixed with sweat. Mixing colours together when washing can also make colours bleed together. UV rays can also damage delicate fabrics. Hair dye can run when rinsing.