Doctors

What is an itch?

Itch is an irritation in the skin that elicits an urge to scratch. Itches are a common problem and can be localized (limited to one area of the body) or generalized (occurring all over the body or in several different areas). The medical term for itching is pruritus. Generalized itch, for obvious reasons, is more difficult to treat than localized itch. Itches can also occur with or without skin lesions (for example, bumps or blisters). An itch that is accompanied by visible skin abnormality usually should be evaluated by a physician and, in some cases, by a dermatologist since the problem is likely to be a condition that requires specialized medical treatment (for example, eczema,scabies, etc.).

What causes itching?

Itching can be caused by many conditions. Probably the most common cause of itch is psychological, that is, due to stress,anxiety, etc. Stress also can aggravate itch from other causes. Dry skin is another frequent cause of itch. Many people also report sunburn itch following prolonged exposure to UV radiation from the sun. Other causes include metabolic and endocrine disorders (for example, liver orkidney disease, hyperthyroidism), cancers (for example, lymphoma), reactions to drugs, and diseases of the blood (for example, polycythemia vera). Itching is common withallergic reactions. Itching can also result from insect stings and bites such as from mosquito or flea bites.

Infections and infestations of the skin are another cause of itch. Common infectious causes of itch include a fungal infection of the crotch (tinea cruris) commonly known asjock itch, as well as vaginal itching and/or anal itching from sexually transmitted diseases (STDs) or other types of infections. Another type of parasitic infection resulting in itch is the so-called swimmer's itch. Swimmer's itch, also called cercarial dermatitis, is a skin rash caused by an allergic reaction to infection with certain parasites of birds and mammals that are released from infected snails in fresh and saltwater. Itch may also result from skin infestation by body lice, including head lice and pubic lice. Most people who have itching, however, do not have a serious underlying condition.

Should I scratch the itch?

Itching usually prompts scratching, which can sometimes lead to a vicious itch-scratch cycle. Scratching can initially feel so satisfying, but prolonged scratching just leaves you with irritated skin that can still itch and often causes itching itself! Since scratching provides only temporary relief and doesn't promote healing of the underlying problem, it is best to avoid scratching if at all possible. If scratching breaks open the skin, bacterial infection can set in. And if scratching continues for many months or years, the area that is scratched may develop thickened skin (lichenification) or pigmentation that darkens the area.

The best way to allow irritated skin to heal is to stop scratching it. However, will power often is not enough since the urge to scratch can be compelling. Here are some general measures to help control itch, regardless of the cause.

What are topical (external) itch treatments?

Cold applications: Because cold and itch travel along the same nerve fibers, the use of cold can "jam the circuits" and deaden itch. Methods of applying cold include

• cool water, either by running tap water over the affected area or placing a cold clean washcloth on the skin;



• cool showers; and



• ice packs, either the commercially available type or ice cubes in a plastic bag.

Hot water (in the shower, for instance) feels good temporarily, but it often leaves you feeling itchier later. Therefore, the use of hot water is not recommended.

Anti-itch creams and lotions: Look for over-the-counter (OTC) remedies with these ingredients:

• camphor,



• menthol,



• phenol,



• pramoxine,



• diphenhydramine, and



• benzocaine (or one of the other "caine" anesthetics).

You can apply these products over and over -- every few minutes if needed. These preparations help numb the nerve endings and stop you from a frenzy of scratching, which leaves the skin raw, sore, and even itchier.

Although hydrocortisone-containing creams and lotions are often promoted as itch-reducers, this ingredient only helps an itch that is caused by a rash responsive tocortisone, such as eczema and seborrhea. Since OTC hydrocortisone-containing creams and lotions are weak (even so-called "maximum-strength" products are only 1%), they aren't too helpful for itch even in responsive conditions. When itching is caused by irritations of other sorts (insect bites, for instance), hydrocortisone doesn't help much at all. If you use hydrocortisone for 10 days and experience no improvement, you should see a physician to help determine the cause of your itch.

What are oral itch treatments?

Traditionally, antihistamines are used to treat itch. Examples include diphenydramine and chlorpheniramine. These medicines can induce drowsiness in many people and must be used with care before driving a car or operating heavy machinery. Although antihistamines may help itch, they seem to do so mainly by helping people fall asleep and avoid scratching at night. If falling or staying asleep is not your main problem, one of the non-sedating antihistamines may be tried. Loratidine and fexofenadine are examples of the newer, second-generation antihistamines that are available OTC. The second-generation antihistamines do not have the sedating effects of the older, first-generation antihistamines.

When should the doctor be consulted for itching?

If home treatment isn't helping, or you notice that scratching is affecting the skin being scratched (infection, lichenification, or pigmentation), or the itch is disturbing your sleep, you should consult a doctor to ascertain why you're itching. A doctor can also prescribe stronger cortisone-based creams (for eczemas and allergies) and prescription-grade antihistamines, if necessary, or treat the underlying condition that is causing the itch.