My son has a dry rash on his back but no where else what is it? he's one years old.

Too little info: This could be many different things. Eczema, viral rash, allergic rash, etc. If you are worried, please seek the advice of your primary care physician.

May not : Be anything especially this time of year . A lot of us suffer from dry skin from the weather . Use moisturizing soap, lotion or creams. Aquaphor ointment is pretty good for dry , cracked skin . Apply as often as needed. If concerned, take him to the doctor.