1 Heredity - Heredity plays a major role in hair loss by determining the sensitivity of hair follicles to androgens , which can shrink hair follicles and lead to hair loss . This is known as androgenetic alopecia or pattern baldness .

2 Hormonal imbalances - Hormonal imbalances can also cause hair loss . For example - an excess of androgens , such as testosterone can lead to hair loss . Fortunately , hair loss due to hormonal imbalance is usually temporary and reversible !

3 Underlying medical conditions - Medical conditions such as thyroid disorders , lupus and iron deficiency anaemia , can also cause hair loss . These conditions can disrupt the normal hair growth cycle and lead to thinning or shedding of the hair !

4 Nutrient deficiencies - Dietary deficiencies can also contribute to hair loss . A lack of protein , iron and other nutrients can cause the hair to become weak and brittle , leading to hair loss .

5 Medication side effects - Certain medications , such as those used to treat cancer , high blood pressure and depression can also cause hair loss as a side effect .