Itchiness refers to an unpleasant sensation that causes the urge to scratch. The medical term for itchiness is pruritus. The itchiness can be limited to a certain part of the body or spread all over the body. Itching can be linked with a rash that might be the cause or a result of the scratching. In some individuals, there might be no evident rash linked with the itchiness.
Regardless of the absence or presence of the rash, the itchiness can be debilitating particularly at night time once the individual is trying to sleep.
Why itchiness occurs
Itchiness and pain are closely linked sensations since the same nerves send out both signals to the brain. Once the area of skin is scratched, the same area might become even itchier, thus resulting to an increased urge to scratch the area which is known as the itch-scratch cycle. Generally, the itchiness can be linked to an issue with the skin or another underlying condition of the body. Once the itchiness is localized to a particular region of the skin, a systemic disease is not the cause.
Causes of itchiness
The causes of itchiness can be divided into localized and generalized. The areas of itchiness that are localized on a single part of the body are more likely triggered by a skin issue. The area of the body that itches can indicate a possible cause.
Generalized itchiness can be due to various skin diseases as well as systemic disease. Skin diseases that trigger itchiness all over the body include atopic dermatitis, hives and contact dermatitis. The itchiness can also be triggered by certain medications, infections, liver disease, iron deficiency, kidney disease, low or high thyroid function as well as cancers.
Common skin allergies that cause itchiness
There are a number of common allergic skin diseases that causes itchiness which includes hives, atopic dermatitis and contact dermatitis.
Hives
This is an itchy rash that can occur at any age but typically affects children. The rash manifests as elevated red bumps in various sizes and shapes that typically last for only a few minutes to a few hours. In most individuals with hives, swelling of the skin around the mouth, eyes, tongue or hands/feet can occur which is called as angioedema.
Atopic dermatitis
This affects children and young adults which causes itchiness of the skin particularly in the flexural areas of the elbow folds and behind the knees. If the individual scratches the skin, it results to a dry, flaky rash that might be linked with blisters and oozing.
Contact dermatitis
This is due to skin contact with a chemical that results in a rash that appears similar to those caused by poison oak or poison ivy. The plants included in the Toxicodendron family are the common cause of plant-induced contact dermatitis which results to a severely itchy rash that has blisters that ooze and crust after contact with the skin. The individual can also react to various chemicals including sunblock, cosmetics, metals, hair dye, dental materials and topical medications.