Some people are sensitive to water, which causes them to itch. They get itchy when they step into a bath or shower. Water-induced itching has fancy name, aquagenic pruritus.
Although allergic reactions usually cause visible hives, sometimes the skin changes are subtle until you start scratching at your skin.
Stress and fatigue also commonly cause itching without a rash.
Some other causes of itching without a rash include:
Iron deficiency anemia Kidney disease
Thyroid disease — both an under active and over active thyroid can cause itching
Keeping your skin moist will clearly help itching related to dry skin. It often will ease itching caused by other conditions mentioned above. If the itching continues, call your doctor for advice or to set up an appointment.