What are the most common reasons for hair loss in men and women? Hair loss, also known as alopecia, can have various causes, and the specific reason for hair loss can vary from person to person. Some common causes of hair loss include; androgenetic alopecia (male and female pattern baldness), alopecia Areata, telogen effluvium, medical conditions, medications, nutritional deficiencies, traction alopecia, trichotillomania, fungal infections, chemical treatments, menopause, age, poor hair care practices, and radiation therapy. Many of the causes mentioned can affect men and women in equal measure, but some causes are more specific to the gender. Here, we look at some of the most common hair loss causes in men, and some of the most common reasons for thinning hair in women, too. Most Common Hair Loss Causes in Men Over two thirds of men experience hair loss by the age of 40. The most common cause of hair loss in men is androgenetic alopecia, commonly referred to as male pattern baldnes