There are many reasons for hair-fall. It could be stress and lifestyle choices (like smoking). Or it can also be due to pollution, hormonal issues, thyroid imbalance, some drugs, and illness.
As per Ayurveda hair-fall is caused by too much Pitta dosha. You should know that this ancient system of medicine says that there are three doshas and there are five elements that build our bodies. Of the three doshas, Pitta governs the metabolism and digestion. Too much Pitta can throw your hormones out of whack and make your hair fall. “Pitta” roughly translates as “fire”. Too much of it might be due to a hot climate, spicy food, sour or salty food, hot or greasy food, alcohol, coffee, and meats.