“Dandruff can result from dry skin, a buildup of oils on the scalp, sensitive and irritated skin, or, very commonly, an overgrowth of a fungus called malassezia globosa,” explains Saedi, noting that it can affect both oily and dry scalps. A common misconception is that malassezia is harmful; in fact, it’s a normal part of the scalp environment that actually helps break down sebum or the oil on your scalp. However, this process produces oleic acid (a fatty acid found in yeast), which many people are sensitive to.

Dr. Kobets explains that factors such as stress (which can raise cortisol levels, increasing scalp oiliness and suppressing the immune system), poor diet (one that is heavy on processed foods and sugars which causes inflammation in the body and scalp), sweating, and warmer temperatures (such as those experienced in summer or during sports) can exacerbate dandruff. Yeast, which contributes to dandruff, thrives in these warm and moist conditions.

Caspara adds that if someone is experiencing a scalp imbalance and has not changed their environment, products, diet, or washing frequency, they should consult a medical professional to ensure the dandruff is not indicative of an underlying health condition. (This should not be confused with a dry scalp, which can feel tight and itchy due to being stripped of its natural oils by harsh cleansing products, dry weather, or indoor heat.)