The terms itch and pruritus are synonymous, according to DermNet NZ, a service of the New Zealand Dermatological Society. A host of underlying skin conditions can cause these sensations. Determining the cause of constant itching may help some individuals sleep better and prevent anxiety, depression and skin infections caused by chronic scratching.
Contact Dermatitis
Contact dermatitis results from exposure to a substance or material to which the body is sensitive. Common offenders include plants, medications, jewelry, rubber or latex, cosmetics, fabrics, detergents, and fragrances. The reaction is often delayed, causing a rash to appear anywhere from 24 to 48 hours after exposure, according to MedlinePlus. The level of irritation varies, ranging from mild to extreme redness and inflammation, which can lead to open sores.
Psoriasis
Psoriasis is a common skin disease, which affects the life cycle of skin cells, causing them to build up on the skin's surface and form thick scales. In minor cases, itchy red patches can form in small spots. More severe cases can cause major eruptions that cover large areas of skin and cause painful cracking and bleeding. Though treatments exist to relieve symptoms, there are no cures for the disease itself. Nonprescription cortisone creams and exposure to natural sunlight are simple therapies recommended by MayoClinic.com.
Eczema
Eczema is a common skin condition that causes chronic skin irritation, most often on the arms and behind the knees. It may also be accompanied by asthma or hay fever. The exact cause of eczema is uncertain, though it is thought to result from a malfunctioning immune system. Infants and children are most susceptible to eczema. In fact, KidsHealth.org reports that about one child out of 10 develops the condition, causing symptoms to develop within the first few months of life and generally before age 5. Most children, however, outgrow the condition by the time they reach their teen years.
