Redness at the root of the nose can be caused by non-disease factors, or it can be caused by pathological factors such as contact dermatitis, rosacea, seborrheic dermatitis and so on. 1. Non-disease factors: such as frequent nose blowing and friction, causing redness at the root of the nose; or cold weather in winter, the nose by the cold air stimulation caused by local redness. 2. Pathological factors (1) Contact dermatitis: If contact with irritating or allergic substances causes localized irritation or allergic reaction, erythema may appear on the skin lesions, which is manifested as redness at the root of the nose. (2) Rosacea: mostly related to infection, heredity, immunity and other factors, can cause capillary dilation at the root of the nose, thus manifesting as redness at the root of the nose. (3) Seborrheic dermatitis: it is a chronic inflammatory disease of the skin, which is considered to be related to infection, heredity, excessive sebum secretion and other factors, and the lesions may show symptoms such as erythema, itchiness, greasy flaking, etc., which may be manifested as redness at the root of the nose. After excluding non-disease factors, it is recommended to go to the hospital in time to find out the cause of the redness, and actively under the guidance of the doctor to carry out targeted treatment, so as not to delay the condition.