Allergies Skin Allergies Understanding Pruritus Localized and Generalized Causes of Itchy Skin Print By Daniel More, MD | Medically reviewed by a board-certified physician Updated November 27, 2018 Smith Collection / Getty Images More in Allergies Skin Allergies Nose & Eye Allergies Drug & Latex Allergies Contact Dermatitis Food Allergies Animal & Insect Allergies Urticaria & Angioedema Common Treatments Pruritus refers to an unpleasant sensation that causes the need to scratch, commonly called itching by most people. Itching may be localized to a certain area of the body or can be all over or generalized. When there is a rash that goes along with the pruritus, the cause is often easily determined and treated. However, the most difficult cases of pruritus are those without an associated rash. Biology of Itching Itching occurs when nerve fibers in the skin send a message to the brain via nerves. Itching and pain are closely related sensations, in that the same nerves transmit both signals to the brain. Pruritus may be caused by a local reaction in the skin (localized pruritus) or a systemic disease that triggers widespread itchiness (generalized pruritus). In some cases, the cause may be psychological or unknown (idiopathic). In addition to whatever causes an itch in the first place, scratching can often lead to even more itching. This is referred to as the scratch-itch cycle and becomes important in treating the itch no matter the underlying cause. Localized Pruritus When itching occurs on only one part of the body, it is usually caused by a problem in the skin. The specific area of the body that itches may give a clue as to the cause of the itch. Causes of localized pruritus by body part include: Whole body: atopic dermatitis, contact dermatitis, psoriasisScalp: psoriasis, head lice, seborrheic dermatitisEyelids: allergic conjunctivitis, allergic dermatitisNose: allergic rhinitis (hay fever)Ears: otitis externa (swimmer's ear).Trunk: psoriasis, atopic dermatitis, folliculitis, scabiesArms: psoriasis, atopic dermatitis, brachioradialis pruritisLegs: atopic dermatitis behind the knees, pruritic rashes of the knee, xerosis (dry skin), dermatitis herpetiformisHands and feet: contact dermatitis, atopic dermatitis, pompholyx, ringworm, scabiesGroin or armpits: tinea cruris (jock itch), yeast infectionsAnus: pruritus ani, pinworms, hemorrhoids Generalized Pruritus While generalized itching can be caused by skin conditions, systemic disease is the culprit in around 50 percent of cases. Some of the conditions and causes of generalized itching, especially when a rash is not present, include: Allergies (including anaphylaxis and systemic dermatitis)Medications (including drug-induced allergies or demyelination)Liver disease (typically later-stage disease)Iron deficiencyNeuropathic itch (caused by nerve entrapment or degeneration) Thyroid disease (both hyperthyroidism and hypothyroidism)Kidney disease (especially during dialysis)Cancer (including leukemias and lymphomas)Parasitic infectionsHIV (commonly experienced soon after infection)Pregnancy If you develop generalized itching with or with a rash, your doctor will want to take a careful history and perform a physical exam. Tests for generalized pruritus may include a complete blood count, kidney function tests, liver function tests, thyroid function test, a stool culture, and an HIV test. Treatment The best treatment of pruritus is to fix the underlying cause of the itching, whether that is a skin condition or a systemic disease. Until the underlying problem is corrected, treatment may be needed to control the itch and reduce the itch-scratch cycle. Non-specific treatments for itching include topical steroid creams, oral antihistamines, and good skin care. Tips for Coping With Pruritus Bathing should be limited to short, cool showers.Only apply soap to the groin, armpits, anal area, under the breasts, and areas of oily skin.Apply a mild moisturizing cream immediately after bathing.Humidify your home to least 40 percent, especially during dry, cold months.Avoid contact with wool, fiberglass, detergents, or other topical irritants.Do not scratch. If you have severe or persistent symptoms of itching, especially generalized pruritus, see your doctor for appropriate evaluation and treatment. Best Creams for Itchy Skin Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Email Address Sign Up There was an error. Please try again. Thank you, , for signing up. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Ebata, T. Drug-Induced Itch Management. Current Problems in Dermatology. 2016. 50:155-63. Mettang, T. Uremic Itch Management. Current Problems in Dermatology. 2016. 50:133-41. Rajagopalan, M., Saraswat, A., Godse, K. et al. Diagnosis and Management of Chronic Pruritus: An Expert Consensus Review. Indian Journal of Dermatology. 2017. 62(1):7-17. Savk, E. Neurologic Itch Management. Current Problems in Dermatology. 2016. 50:116-23. Continue Reading