Itchy rash may be caused by neuropsychiatric, allergic, mosquito bites and environmental factors. 1. Neuropsychiatric factors: long-term maintenance of bad mood, such as anxiety, fatigue and other neuropsychiatric factors, may induce or aggravate itchy rash. 2. Allergy: If you are allergic to many kinds of food or drugs, you may be more prone to itchy rash. 3. Mosquito bites: localized mosquito bites can cause inflammation, which may lead to itchy rash. 4. Environmental factors: Itchy rash may be more likely to occur if you have been in a dirty, humid environment for a long time. There are many causes of itchy rash, we suggest that patients go to the hospital to consult the doctor to understand the relevant matters.