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 signs and symptoms of the condition?
A doctor will ask the person questions to learn more about the nature of the itching. These may include:
Other things may also be important in certain cases. For example, if a person has genital itching, information about his or her sexual activity or menstrual periods may be important.
- When did the itching start?
- Where is the itching located? Is it focused in one spot or all over the body?
- Is the itching constant or does it come and go?
- Have any friends, relatives, or other close contacts had itching recently?
- What medications, herbs, or illegal drugs, if any, is the person taking?
- What other medical conditions does the person have?
- Is there anything makes the itching worse or better, such as a particular season or a specific type of soap?
- Are there other symptoms such as a skin rash, fever, weight loss, or runny nose that accompany the itching?
What are the causes and risks of the condition?
Itching has many possible causes. These may include:
Other causes are also possible. Sometimes, no cause can be found.
- 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 sulpha 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
- body wide infections such as chickenpox
- cancer or tumours, such as certain blood cancers known as lymphoma, multiple myeloma, and polycythemia vera. Other tumours, such as a skin cancer called melanoma, stomach cancer or a carcinoid tumour, can also cause itching.
- conditions with body-wide effects, such as chronic renal failure, certain liver conditions, such as cholestasis of pregnancy, or iron-deficiency anaemia
- autoimmune disorders, conditions in which a person's immune system attacks his or her own body. Examples include Sjogren's 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.
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?
The first step in figuring out the cause is a medical history and physical examination. This may be sufficient to make a diagnosis. In other cases, further tests may be needed.
The tests that are ordered will depend on the suspected cause of the itching. For example, blood tests can be used to help diagnose some blood cancers, hormone imbalances, and kidney failure. In cases of a skin rash, a biopsy of the skin may be needed. In this procedure, a small piece of skin is removed and sent to the laboratory for further testing. Special x-ray tests or other procedures may be needed in certain cases.
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 diphenhydramine can be helpful. Another type of medication is topical corticosteroids such as hydrocortisone cream. Occasionally, oral corticosteroids such as prednisone 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 infections. A thyroid hormone imbalance can often be corrected with medications. Surgery, chemotherapy, or radiation therapy may be needed to treat a tumour or cancer.
What are the side effects of the treatments?
Side effects depend on the treatments used. All medications have 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 as itching caused by scabies.
How is the condition monitored?
Any change or response to treatment can be reported to the doctor. Other monitoring is related to the cause. For example, people with thyroid hormone problems may need thyroid function tests to monitor their thyroid hormone level.
Author: Adam Brochert, MD
Reviewer: eknowhow Medical Review Panel
Editor: Dr John Hearne
Last Updated: 18/09/2004
Potential conflict of interest information for reviewers available on request