There are several main causes of slow hair growth: 1. chronic vitamin deficiency, a common cause of slow hair growth worldwide. 2. excessive stress, people living in harsh, controlling or abusive situations show retarded hair growth. 3. hypothyroidism, often considered the root cause of slow hair growth in children. 4. produces alopecia, hair loss is the most common factor, this disease is seen in both males and females and takes many forms.5. Increased hormones inhibit the transmission of hair receptors and genetic or hereditary baldness in both males and females show slow hair growth.6. Individuals have a short hair growth cycle.7. Malnutrition, which causes hair to be deprived of nutrients and the roots to break easily, can lead not only to slow hair growth but also to hair loss.