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Dx Skin Allergy Treatments :

Skin Allergies

The Merck Manual Home Edition
" Itching can be very uncomfortable. It is one of the most common reasons people see dermatologists. Itching can be triggered by wool fibers or irritants, such as solvents or cosmetics.

Itching can result from disorders that affect the skin, the nervous system (which senses itching), or other parts of the body (such as bile ducts or kidneys) or from drugs. Causes that affect more of the body than just the skin are called systemic causes.

Itching makes people want to scratch. Scratching temporarily relieves itching but can damage the skin, sometimes resulting in more itching or infection. Over time, the skin can become thick and scaly.

When the Skin Is Dry:
Dry skin (xerosis) is common, especially among people past middle age. Common causes are cold weather and frequent bathing. Bathing washes away surface oils, allowing the skin to dry out. Dry skin may become irritated and often itches—sometimes it sloughs off in small flakes and scales. Scaling most often affects the lower legs. Rubbing or scratching dry skin can lead to infection and scarring.

A form of severe dry skin is called ichthyosis. Ichthyosis can be an inherited disorder or can result from a number of other disorders, such as an underactive thyroid gland (hypothyroidism), lymphoma, and AIDS.

The key to treating simple dry skin is keeping the skin moist. Taking fewer baths allows protective oils to remain on the skin. Moisturizing ointments or creams containing petroleum jelly, mineral oil, or glycerin can also hold water in the skin. Harsh soaps, detergents, and the perfumes in some moisturizers irritate the skin and may further dry it.

When scaling is a problem, solutions or creams containing salicylic or lactic acid or urea may help remove the scales. For some forms of severe ichthyosis, creams containing substances related to vitamin A, such as tretinoin, help the skin shed excessive scales.

The most common causes of itching are related to skin disorders:
*Dry skin
*Eczema (also called atopic dermatitis)
*Contact dermatitis (an allergic rash resulting from direct contact with a particular substance)
*Fungal skin infections

Systemic causes are less common but are more likely if there is no visible skin problem. Some of the more common systemic causes are
*Allergic reactions that have internal effects—for example, to foods, drugs, bites, or stings (internal allergic reactions)
*Disorders of the gallbladder or liver, such as gallstones
*Chronic kidney disease
*Less common systemic causes include an overactive thyroid gland (hyperthyroidism), an underactive thyroid gland (hypothyroidism), diabetes, iron deficiency, and polycythemia vera (a cancerous overproduction of red blood cells).
*Drugs can cause itching by causing allergic reactions. Drugs can also cause itching without causing an allergic reaction. For example, morphine and some radiopaque dyes given by vein (intravenously) may cause itching. s

Not every episode of itching requires immediate evaluation by a doctor. The following information can help people decide whether a doctor's evaluation is needed and help them know what to expect during the evaluation. Most conditions causing itching are not serious.

Warning signs:
The following may indicate that the cause could be serious:
*Weight loss, fatigue, or night sweats—symptoms that may indicate a serious infection or a tumor
*Weakness, numbness, or tingling—symptoms that may indicate a nervous system disorder
*Abdominal pain or a yellowish discoloration of the skin and eyes (jaundice)—symptoms that may indicate a gallbladder or liver disorder
*Excessive thirst, abnormally frequent urination, and weight loss—symptoms that may indicate diabetes

When to see a doctor:
People who have weight loss, fatigue, or night sweats should see a doctor as soon as convenient, probably within a week or so. People with any of the other warning signs or with severe itching should probably see a doctor immediately or as soon as possible.

What the doctor does:
Doctors pose many questions and look at the skin. Often, a person needs to undress so that the entire skin surface can be checked. If no clear cause is found after checking the skin, doctors may do a complete physical examination to check for systemic causes. Testing may be necessary to diagnose certain systemic causes and sometimes skin disorders.

If itching is widespread and begins shortly after use of a drug, that drug is a likely cause. If itching (usually with a rash) is confined to an area in contact with a substance, particularly if the substance is known to cause contact dermatitis, that substance is a likely cause. However, allergic causes of widespread itching can be difficult to identify because affected people have usually eaten several different foods and have been exposed to many substances that could cause an allergic reaction before itching develops. Similarly, identifying a drug that is causing the reaction in a person taking several drugs may be difficult. Sometimes the person has been taking the drug causing the reaction for months or even years before a reaction occurs.

Most causes of itching can be diagnosed without testing. If the diagnosis of a skin abnormality is not clear from its appearance and the person's history, removal (biopsy) of a skin sample may be necessary so that it can be analyzed. If the cause of itching seems to be an allergic reaction but the substance causing the allergic reaction is not evident, skin testing may be necessary. In skin testing, substances that can cause allergic reactions on contact are applied to the skin, either in a patch (called patch testing) or with a small needle (called prick testing).

If the cause seems not be an allergic reaction or skin disorder, testing is done based on the person's other symptoms. For example, tests may be done for gallbladder or liver disorders, chronic kidney disease, thyroid disorders, diabetes, or cancer.

Disorders that cause itching are treated. Sometimes other measures can also help relieve itching. Skin care:
*Skin care measures can help relieve itching regardless of cause. Baths or showers should be short, no more frequent than necessary, and taken with cool or lukewarm (not hot) water. Using moisturizing soap and skin lubricants can also help, as can humidifying dry air (for example, in winter) and not wearing tight or wool clothing.

Topical treatments:
*Topical treatments can be applied to the skin if only a specific area is affected. To be effective, capsaicin cream should be used for at least 2 weeks. It tends to burn, but the burning decreases over time. Menthol and camphor creams have strong odors but can be used, as can tacrolimus or pimecrolimus creams.

*Corticosteroid creams can help relieve itching and often clear up the rash and other skin abnormalities in disorders such as eczema, contact dermatitis, psoriasis, and lichen simplex chronicus. Corticosteroids should usually not be used when the skin is infected, when an infestation is present, when no rash or skin abnormalities are present, and when the cause is systemic.

*Type B ultraviolet light can relieve itching but can cause sunburn-like effects and increases the risk of skin cancers.

Systemic treatments:
Systemic treatments are drugs that are taken internally, usually by mouth. They are used if itching is widespread or if topical treatments are ineffective.

*Antihistamines, particularly hydroxyzine, are used most often. Some antihistamines, such as cyproheptadine, diphenhydramine, and hydroxyzine, cause drowsiness. They help relieve itching and, when used before bedtime, aid in sleep. However, these drugs are usually not given during the day to older people, who are at higher risk of falling because of drowsiness.
*Cetirizine and loratadine cause less drowsiness but rarely can have this effect in older people.
*Fexofenadine causes less drowsiness but sometimes causes a headache.
*Doxepin makes people very drowsy and is effective, so it can be taken at bedtime if itching is severe.

*Cholestyramine is used to treat itching caused by gallbladder or liver disorders, chronic kidney disease, or polycythemia vera. However, cholestyramine has an unpleasant taste, causes constipation, and can decrease absorption of other drugs.
*Naltrexone can be used to treat itching caused by gallbladder or liver disorders but may increase pain if pain is present.
*Gabapentin can help relieve itching caused by chronic kidney disease but can cause drowsiness.

Key Points:
Itching usually results from dry skin, a skin disorder, or an allergic reaction. If the person has no rash or skin abnormalities, the cause may be a drug, an allergic reaction that has internal effects, or a systemic disorder. Skin care measures (such as limiting bathing, moisturizing the skin, and humidifying the air) can usually help relieve itching. Itching can usually be relieved by topical or systemic treatments."

Medications Used in Treatment:
1. Corticosteroids: Cutivate®/fluticasone propionate, triamcinolone; see list
2. Antihistamines: Promethegan®/promethazine; see list
3. Skin Barrier Emollients: Epiceram®, Neosalus®, Prumyx®, Aquaphor®/Epicurium

Suggested links:
*N.H.S. Choices/ Skin Rashes in Children
*Medscape/ Skin Rashes not to be Missed

* [Editor] The JAMA article reports that 50% of elderly patients have xerosis (dry skin). They note that calcium channel blockers and hydrochlorothiazes are an important cause of pruritic (itchy) skin. An older therapy for Lichen Sclerosis (dry skin of the vagina/vulva) was to use an emollient such as Aquaphor® with a small concentration of 2% testosterone to thicken the skin. A one milliliter solution could be rubbed every other day into a different 2 inch square area where the skin is thin in men without prostate or testicular cancer risk. The dose is low enough so that the women will not exacerbate hirsuitism.

*[Editor Fifty years ago, German physicians made a preparation with nandrolone decanoate and a steroid for use on the elderly with fragile, skin breakings.
*[Editor] As noted in the webpage on Hives and Reynaud's phenomenon, stanozolol oral, injectable to topical has effectiveness.

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