Itchy skin

Symptoms

Itchy skin may occur in small areas, such as on an arm or leg. Or your whole body may feel itchy. Itchy skin can occur without any other noticeable changes on the skin. Or it may be associated with:

• Redness
• Bumps, spots or blisters
• Dry, cracked skin
• Leathery or scaly texture to the skin

Sometimes itchy skin lasts a long time and can become very intense. As you rub or scratch the area, it gets itchier. And the more it itches, the more you scratch. Breaking this itch-scratch cycle can be challenging.

Causes

Dry skin

Itchy skin that isn't accompanied by other obvious skin changes, such as a rash, is most often caused by dry skin (xerosis). Dry skin usually results from environmental factors that you can wholly or partially control. These include hot or cold weather with low humidity levels, long-term use of air conditioning or central heating, and washing or bathing too much.

Other possible causes

Other conditions cause itchy skin as well. Skin disorders, internal diseases, allergies and drug reactions top the list.

• Skin conditions and rashes. Many skin conditions cause itchy skin, including psoriasis, inflammation of the skin (dermatitis), scabies, lice, chickenpox, hives and dermatographism. In these cases, the itching usually affects specific areas and is accompanied by other signs, such as red, irritated skin or bumps and blisters.
• Internal diseases. These include liver disease, malabsorption of wheat (celiac disease), kidney failure, iron deficiency anemia, thyroid problems and cancers, including leukemia and lymphoma. In these cases, the itching usually affects the whole body, rather than one specific area. The skin may look otherwise normal except for the scratched areas.
• Irritation and allergic reactions. Wool, chemicals, soaps and other substances can irritate the skin and cause itching. Sometimes the substance causes an allergic reaction, such as in the case of poison ivy or cosmetics. Food allergies also may cause itchy skin reactions.
• Drugs. Reactions to drugs, such as antibiotics, antifungal drugs or narcotic pain medications, can cause widespread rashes and itching.
• Pregnancy. Some women experience itchy skin during pregnancy, especially on the abdomen, thighs, breasts and arms. Also, itchy skin conditions, such as dermatitis, can worsen during pregnancy.

Complications

Prolonged itching and scratching may increase the intensity of the itch, possibly leading to neurodermatitis (lichen simplex chronicus). Neurodermatitis is a condition in which an area of skin that's frequently scratched becomes thick and leathery. The patches can be raw, red or darker than the rest of your skin. Persistent scratching can also lead to a bacterial skin infection and permanent scars or changes in skin color.

Diagnosis 

Your doctor is likely to conduct a physical exam and ask questions about your medical history, including when the itching started, what factors make it better or worse, and how you care for your skin.

You may have certain diagnostic tests — such as blood tests — if your doctor suspects that your itchy skin is the result of an underlying medical condition, such as liver disease or iron deficiency anemia.

Through examination and tests, your doctor may determine that your itching is, in fact, a symptom of another skin condition. Related itchy skin conditions include:

• Dermatitis. Also called eczema, dermatitis is an inflammation of the skin. There are different types of dermatitis, and the disorder can have many causes and occur in many forms. Generally, dermatitis describes swollen, reddened and itchy skin.
• Psoriasis. With psoriasis, the life cycle of skin cells speeds up, resulting in a rapid buildup of rough, dead skin cells. These skin cells accumulate, forming thick silvery scales and itchy, dry, red patches that are sometimes painful.
• Tinea infections. Athlete's foot, ringworm of the body, ringworm of the scalp and jock itch are caused by a fungal infection that develops on the top layer of your skin. These infections often cause round, flat patches of itchy skin.
• Hives. Hives are raised, itchy red bumps of various sizes that appear and disappear on your skin. Allergic reactions to medications or foods can cause hives. Dermatographism is a condition where stroking the skin causes hive-like lesions to develop in the touched areas.
• Lice. Body lice, pubic lice and head lice are common causes of intense itching. Lice are tiny, wingless, parasitic insects that feed on your blood. The infestation, which is easily spread through close physical contact, can cause small, red bumps.
• Scabies. Scabies is caused by a tiny, eight-legged burrowing mite called Sarcoptes scabiei. The presence of the mite leads to intense itching in the area of its burrows. Scabies is contagious and can spread quickly through close physical contact.

References

http://www.nhs.uk/Conditions/Itching/Pages/Causes.aspx

http://www.medicinenet.com/itch/article.htm

http://www.healthline.com/health/itching

http://www.webmd.com/skin-problems-and-treatments/guide/skin-conditions-pruritus

http://www.drugs.com/symptom/itching-without-rash-1.html