Redness and itchiness on the chest are considered to be possibly ringworm, pityriasis pilaris, and solar dermatitis, as follows: 1. Ringworm: can appear in the chest area as annular erythema with papules and blisters on the edges. This disease is caused by fungal infections such as Trichophyton rubrum, Microsporum canis, and flocculent dermatophytes, and patients can use topical terbinafine hydrochloride gel. 2. Pityriasis pilaris: This is caused by infection with Sphaerococcus furfur and can appear as light red or brownish-red patches with mild itching. Patients can choose to apply selenium disulfide lotion, can also apply clotrimazole ointment, bifidazole ointment for treatment; 3, solar dermatitis: usually occurs in the chest bit exposure, can be caused by allergies due to ultraviolet radiation of sunlight.