Pruritus is the medical word for itch. It is defined as a sensation that provokes the desire to scratch. The exact cause of an itch is unknown and is a complex process. Ultimately it involves nerves in the skin responding to certain chemicals, such as histamine, and then processing these signals in the brain.
Pruritus can be a symptom of certain skin diseases. There are many skin diseases that may have itching associated with a rash as a prominent symptom. Examples would be hives, chicken pox and eczema. Some skin conditions only have symptoms of pruritus without having an apparent rash. Dry skin, for example, is very common in the elderly, and can really itch, especially in the winter, with no visual signs of a rash.
Some parasitic infestations of the skin, such as scabies and lice, may be very itchy. Often the dermatologist will be able to diagnose these conditions by examining the skin.
There are several internal diseases that may cause itch. The most common example is kidney failure. Other types of internal diseases that may cause pruritus are some types of liver disease, including Hepatitis C, and thyroid disease, including both hyper (too much) and hypo (too little) thyroid hormone levels. Some blood disorders, such as iron deficiency anemia, polycythemia vera and multiple myeloma, can cause itch. Neurological conditions such as pinched nerves and strokes also may lead to itch.
Although there are many causes for Pruritus, there are some basics that apply to most treatments. Hot bathing or showering should be avoided. Only bathe in tepid or lukewarm water. Wearing light clothing and a cool work or domestic environment all help to reduce the severity of itching. Soaps often dry out the skin. Use mild soaps only in odor bearing regions. After bathing, be sure to completely rinse off the soap film, pat the skin lightly, and immediately apply a moisturizing lotion or cream. For itchy conditions where blistering or weeping of the skin is present, such as chicken pox or poison ivy, taking a cool oatmeal bath or using topical drying agents such as Calamine may be helpful. Although Pruritus is an often disrupting and disabling symptom it generally responds well to treatment.
Your dermatologist will determine the cause of the itch. This will require an examination of the skin and possibly a blood test or biopsy. Once the cause is known, the dermatologist will prescribe the best treatment for your condition.