Hair loss resulting from childhood irradiation for tinea capitis has been linked to mental health effects in women. However, the association of hair loss severity with mental health in this population is unknown. To address this gap, this study examined the association between hair loss severity and mental health outcomes in women irradiated for tinea capitis in childhood as well as the factors that contribute to these outcomes. Medical records, held at the archives of the Israel National Center for Compensation of Scalp Ringworm Victims, were retrospectively reviewed for 2509 women who received compensation for full or partial alopecia resulting from irradiation for tinea capitis. Mental health outcomes were determined by the number of mental health conditions reported. The results show that among women with more hair loss, risk was increased for a range of mental health problems, especially social anxiety (RR 2.44, 95% CI 2.09–2.87). Hair loss severity emerged as a significant predictor of mental health, adding to the effects of other predictors such as family, social and physical health problems (β = 0.13, 95% CI 0.27, 0.56). The effects of hair loss severity on mental health outcomes were mediated by women’s negative social experiences (indirect = 0.72, 95% bias-corrected confidence interval, 0.53–1.08). Healthcare professionals supporting women with hair loss after irradiation for childhood tinea capitis should be alert to a history of severe levels of hair loss.