What is an itchy scalp? An itchy scalp is an inflammatory reaction of the skin underneath the hair on your head. An itchy scalp is a common problem, particularly among adults. An itchy scalp may or may not be associated with a visible rash or broken skin. The severity, frequency and duration of an itchy scalp depend on the underlying cause. Some causes of an itchy scalp, such as dandruff (seborrheic dermatitis), can be relatively minor. However, an itchy scalp can also be due to more serious conditions, such as infection, inflammation, parasite infestation, autoimmune disorders, and allergies. In some cases, an itchy scalp can begin suddenly and disappear quickly by itself or with minimal treatment, such as a mild allergic reaction or sensitivity to a new hair product. An itchy scalp can also occur over a relatively long period of time, such as when itching is due to scalp psoriasis. An itchy scalp can occur by itself or with other symptoms, such as a rash or visible bumps on the scalp and nape of the neck. In addition, excessive scratching of an itchy scalp can introduce bacteria or fungus into the layers of the scalp, resulting in secondary infections. Tell your health care provider about any symptoms that occur with an itchy scalp. This information helps your health care provider diagnose the condition. An itchy scalp can be caused by a serious underlying condition that requires medical treatment, such as lupus or hypothyroidism. If you have an itchy scalp that is persistent, seek prompt medical care to talk with your medical professional about your symptoms.