Why does radiation cause hair loss?

Radiation, particularly ionizing radiation such as X-rays and gamma rays, can cause hair loss or alopecia. This effect primarily occurs in rapidly dividing cells, including those in the hair follicles. Here are the main reasons why radiation can lead to hair loss:

Damage to Hair Follicle Cells: Ionizing radiation has enough energy to damage the DNA of cells in the hair follicles, which are responsible for hair growth. When healthy cells in the hair follicle are irradiated, their ability to divide and produce hair strands can be disrupted. This damage compromises hair growth and can result in hair thinning and eventual hair loss.

Cell Death: Higher doses of radiation can cause severe damage to hair follicle cells, leading to their death. When a significant number of hair follicle cells are destroyed, the affected area may experience complete hair loss.

Growth Cycle Disruption: Radiation therapy typically involves multiple treatment sessions spaced out over several weeks. This can interfere with the normal hair growth cycle, which consists of three phases: growth (anagen), regression (catagen), and resting (telogen). Radiation can disrupt the synchronization of these phases, causing premature entry of hair follicles into the resting phase, leading to hair shedding.

Individual Variations: The severity and pattern of hair loss can vary from person to person. Some individuals may experience temporary hair loss during treatment, which usually regrows once radiation therapy is completed. Others may experience permanent hair loss, especially in areas that receive more significant radiation doses. Factors like overall health, cumulative radiation dose, and previous hair treatments can influence the extent of hair loss.

It is important to note that hair loss induced by radiation is typically a transient effect. Once radiation treatment is completed, hair usually starts to regrow, although it may take several months to return to its pre-treatment state. In cases of permanent hair loss, alternative hair restoration options can be discussed with a healthcare professional.