Itching is an irritating sensation in the skin that makes a person want to scratch.
What is going on in the body?
Most people have itching from time to time. Often, there is no clear reason for the itching. Usually, the sensation goes away in a few seconds or after scratching. In some cases, however, itching can persist. The causes of continued itching range from mild to life threatening.
What are the causes and risks of the condition?
Itching has many possible causes. These may include:
- allergic conditions, such as skin conditions known as atopic dermatitis or contact dermatitis. Allergic rhinitis is an allergic condition that can cause itchy eyes and nose. Drug reactions, common with penicillin or sulfa antibiotics, are another common cause of allergic itching.
- skin conditions, such as psoriasis, bullous pemphigoid, or abnormally dry skin, sometimes called xerosis
- irritation of the skin. This may be from sunburn, insect bites, chemicals, soaps, poison ivy or other causes.
- skin infections, such as scabies
- bodywide infections such as chickenpox
- cancer or tumors, such as certain blood cancers known as lymphoma, multiple myeloma, and polycythemia vera. Other tumors, such as a skin cancer called melanoma, stomach cancer or a carcinoid tumor can also cause itching.
- conditions with bodywide effects, such as chronic renal failure, certain liver conditions, such as cholestasis of pregnancy, or iron-deficiency anemia
- autoimmune disorders, conditions in which a person's immune system attacks his or her own body. Examples include Sjögren syndrome and multiple sclerosis.
- hormone imbalances such as those that occur in diabetes. Low thyroid hormone levels called hypothyroidism and high thyroid hormone levels, known as hyperthyroidism, both can cause itching as well.
- psychological causes. These may include anxiety, psychosis or cocaine withdrawal
Other causes are also possible. Sometimes, no cause can be found.
What can be done to prevent the condition?
Prevention is related to the cause. For example, avoiding sunburn or poison ivy can prevent these causes of itching. Getting regular childhood vaccines can prevent chickenpox. Many cases cannot be prevented.
How is the condition diagnosed?
In some cases, the cause of the itching is obvious to the healthcare professional from the medical history and physical exam. In other cases, further tests may be needed, depending on the suspected cause. For example, blood tests can be used to help diagnose some blood cancers, hormone imbalances, and kidney failure.
In cases of a skin rash that itches, a biopsy of the skin may be needed. In this procedure, a small piece of skin is removed and sent to the lab for further testing. Special x-ray tests or other procedures may be needed in certain cases.
Long Term Effects
What are the long-term effects of the condition?
Severe itching can disrupt a person's life. Sleep and other activities may be difficult. Scratching of itchy areas can cause damage to the skin and may result in skin infection. Other long-term effects are related to the cause. For example, cancer can result in death. Multiple sclerosis can result in severe weakness and numbness in certain areas of the body. People with chronic renal failure may need a
kidney transplant or dialysis.
What are the risks to others?
Itching itself is not contagious. However, if the cause is an infection such as scabies or chickenpox, the infection may be contagious.
What are the treatments for the condition?
There are treatments available to reduce itching. Antihistamine medications such as hydroxyzine (i.e., Vistaril) and diphenhydramine (i.e., Benadryl) can be helpful. Another type of medication is topical corticosteroids such as hydrocortisone cream (i.e., Hytone, Tucks Anti-itch ointment). Occasionally, oral corticosteroids such as prednisone (i.e., Sterapred) are used for severe rashes. Other remedies such as calamine lotion are also available.
Treatment of the cause is also important, when possible. For example, antibiotics can be used to treat scabies. A thyroid hormone imbalance can often be corrected with medications. Surgery,
chemotherapy, or radiation therapy may be needed to treat a tumor or cancer.
What are the side effects of the treatments?
Side effects depend on the treatments used. Each medication has its own array of possible side effects. For example, antihistamines can cause drowsiness or confusion.
What happens after treatment for the condition?
Itching from sunburn or poison ivy will go away on its own and no further treatment is needed. Other cases may resolve with treatment, such itching caused by scabies.
How is the condition monitored?
Any change or response to treatment can be reported to the healthcare professional. Other monitoring is related to the cause. For example, people with thyroid hormone problems may need thyroid function tests to monitor their thyroid hormone levels.
Conn's Current Therapy, 1999, Rakel et al.