Patients feel itchy like pins and needles on the back may be suffering from contact dermatitis, but also may be suffering from herpes zoster, skin sweating to stimulate the skin and other reasons, need to be specifically analyzed. 1. Contact dermatitis: patients due to skin contact with certain exogenous stimuli or trigger an allergic reaction will lead to contact dermatitis, manifested by skin erythema, edema, back pins and needles as itchy or even vesicles oozing, etc., to the hospital dermatology department in a timely manner. 2. Herpes zoster: patients infected with herpes zoster virus, when the body resistance is low when the virus reproduction leads to the onset of erythema, blisters before the appearance of the skin will appear pinprick sensation, pain and so on. 3. Skin sweating stimulates the skin: sweat evaporates after the skin sweats, so it will stimulate the skin to produce a tingling sensation, this is a normal situation, you can not have to do the treatment, keep the skin clean. If the back of the skin pins and needles like itching symptoms are serious or last for a period of time did not get better, you should promptly go to the hospital for treatment.