Redness on the nose may be caused by rosacea, seborrheic dermatitis, and follicular worm infection. 1. Rosacea: the etiology and pathogenesis are still unclear, may be related to genetic factors, skin immune function abnormalities, as well as vasoconstriction function abnormalities, which can cause local persistent erythema, and capillary dilation as the main manifestation, so it will cause the phenomenon of blood on the nose. 2. Seborrheic dermatitis: the etiology is still unclear, may be related to the colonization of Malassezia bacteria, skin barrier function is impaired, may cause local erythema, as well as greasy flaking, so it will be manifested as the symptoms of redness on the nose. 3. Trichoderma infection: Infection of the hair follicles on the nose by Trichoderma can cause capillary expansion, congestion and swelling of the hair follicles, which may also be manifested as the phenomenon of redness on the nose. There may be other reasons for the redness on the nose, and you need to go to the hospital first to get a clear picture of the cause of the problem and follow the doctor’s instructions.