The effect of Downton's false statement to Mrs Wilkinson was a violent shock to her nervous system, causing her to vomit and for her hair to turn white and other more serious and permanent physical consequences which at one point threatened her reason, and entailing weeks of suffering and incapacity to her as well as expense to her husband for medical treatment.
Downton's false statement had a significant effect on Mrs Wilkinson, causing her nervous system to react violently, leading to vomiting, hair turning white, and more serious physical issues that threatened her mental stability. This situation also resulted in weeks of suffering and incapacity, along with financial strain for her husband due to medical treatment.