“Unfortunately, brushes don’t just clog hair, but dead skin cells, hair gels, leave-in conditioner, scalp oil, fungus, bacteria, dandruff, and more,” certified trichologist and alodia founder Isfahan Chambers-Harris, Ph.D., tells mbg.

When you brush your hair, this myriad of buildup can travel from the scalp to the brush and back again until you clean it.

You probably don’t actually looked at your comb before and rightly so. But if you shine a flashlight on your tool, you can see white and yellow particles clogging up your brush. It sounds ugly, but sometimes it’s the only way to motivate yourself to brush.

Before you ask, yes, this step is important for the health of your scalp. “If you don’t brush, it can lead to an imbalance in your scalp microbiome, which can lead to scalp conditions like dandruff and scalp infections that can lead to hair loss,” Chambers-Harris notes.

“You can also apply oils, which can contribute to dirtiness in your hair,” adds board-certified dermatologist Hadley King, MD, FAAD. In other words, a dirty hair brush can worsen the oiliness of the hair roots.