Report on the Causes of Itchy Skin by AskDocWeb
Causes of Itchy Skin
An itch can be generalized (itching all over) or it can affect only limited areas of skin. The most common areas affected by itch are:
- Anal itch
- Arms and hands itch
- Eye itch
- Eyelid itch
- Facial itch
- Foot itch
- Jock itch
- Leg itch
- Neck itch
- Scalp itch
- Throat itch
- Under-arm itch
Environmental Causes of Itch
1. Dry Skin (xerosis, or winter itch) is common, especially in old people, and may be caused by cold weather, wind, sunburns, prolonged water exposure, frequent hot baths or just by using soaps such as washing powder and house cleansers. These products can reduce the protective layer of oil on the skin which increases water loss through evaporation thus drying the skin.
2. Sweating produces an itch in a different way. Normal skin has flora (microbes) that thrive on sweat (especially in armpits and groin). The waste products of these microbes cause the skin to itch. Excessive sweating can be caused by primary hyperhidrosis (increased activity of sympathetic nerves or secondary hyperhidrosis as in elevated thyroxine, tuberculosis, or malignancies.
3. Insect Bites and stings from mosquitoes, flies, tics, bees, wasps, ants, spiders, and scorpions can cause itching that ranges from minor localized itchy up to a painful skin infection that may be life threatening. Insect Bites and stings usually heal on their own after several hours or a few days. Some insect bites (especially bees) may cause severe allergic reactions with generalized skin itching and swelling. Any allergic reaction can become life threatening and require immediate medical attention.
4. Infections and Infestations
- Fungi thrive well on moist body areas and folds such as the feet (Athlete’s foot), groin, under breasts, and under arms. The itchy scalp that often accompanies dandruff shedding may also be caused by fungi. (Dandruff also has other causes.)
- Parasitic skin infections from scabies (Sarcoptes scabiei), mites, lice, louse, cutaneous larva migrans also cause itching.
- Intestinal worms may also cause skin itching.
- Bacterial infections:
- Infected acne (Treponema pallidum) is common in adolescents.
- Folliculitis caused by Staphylococcus aureus is common in athletes.
- Hot tub folliculitis may arise after using a pool or hot tub that is not properly treated. It is caused by Pseudomonas aeruginosa. Cercarial dermatitis is also known as swimmers itch or duck itch.
- Impetigo is a contagious skin infection common in children.
- Viral skin infections include measles, rubella, chicken pox, infectious mononucleosis, herpes, and viral hepatitis. All of these commonly produce an itchy skin rash. Itching is common in AIDS.
- Hidradenitis suppurativa, also known as Verneuil’s disease, affects areas on the body that have apocrine sweat glands or sebaceous glands such as the hands, underarms, ears, face, legs, groin, and buttocks. It is not contagious.
5. Irritating Substances
Some substances can cause the skin to itch by irritating the skin without causing any inflammation.
- Fiberglass insulation material, sometimes called glass wool, can cause intense itching
- Detergents and washing powder remove oil from the skin and cause itching.
6. Dermatitis is an inflammation of the skin with a red itchy rash, caused by inhaling, ingesting or touching certain substances. It is not infectious or contagious. There are several types of dermatitis including:
- Contact dermatitis may be either allergic or non-allergic. It appears as limited area of red itchy skin area on the site of contact with wool clothes, necklaces, cosmetics, solvents, etc.
- Photodermatitis is a result of sunlight on chemicals, medications, or cosmetics used on skin.
- There is a generalized exfoliative dermatitis that may be associated with use of some drugs (antibiotics and barbiturates), or by psoriasis.
- Stasis dermatitis occurs mostly in patients with varicose veins on the legs.
- Localized scratch dermatitis is due to long term scratching causing inflammation if the skin.
- Benign mucosal pemphigoid is a chronic, nonhereditary blistering disease that produces itchy blisters.
7. Allergies produce allergic reactions that can occur from a few minutes up to 72 hours after contact with a triggering substance (allergen). Allergies commonly cause itching and tingling sensations around the mouth and in the throat and may be accompanied by facial swelling. Some of the known allergies include:
- Foods and drugs
- Poison ivy and poison oak
- Atopic dermatitis (mostly in children who also have asthma or hay fever).
- Other common allergies are hair dye allergies, allergies to lacquers, etc.
- Hives (urticaria) is a type of allergic reaction with red raised itchy patches of skin.
- Hyper-IgE Syndrome
- Hyperimmunoglobulin E (IgE) syndrome
- Idiopathic hypereosinophilic syndrome
8. The adverse effects of several medications and treatments may cause the skin to itch.
- Medications causing itchy skin
- angiotensin-converting enzyme inhibitors
- hydroxyethyl cellulose
- Drug interactions
- Radiation treatments
- Blood transfusion complications
- Plasma expanders
- Graft-versus-host disease
9. Illegal Drugs and Itching
Cocaine, heroine, ecstasy and LSD abuse may all cause itching.
10. Toxic substances that produce poisoning may also be accompanied by itching.
- Alcohol intoxication
- Ciguatera poisoning, caused by ciguatoxin in some tropical fish, may cause itching that lasts from few hours to several months.
- Acrodynia is severe itching caused by chronic mercury poisoning
- Vitamin A toxicity
- Gold salts
- Nicotinic acid
- Fixed drug eruption
Diseases that produce itching
1. Often itchy skin is the result of a skin condition. The possibilities here include:
- Lichen planus
- Nummular dermatitis, coin-shaped eczema
- Seborrheic dermatitis, yellow, greasy scales
- Perioral dermatitis (mostly seen in women between 20-60) A red rash around the mouth, nose and eyes
2. Gastrointestinal Diseases
- Intestinal parasites
- Dumping syndrome
3. Liver and Biliary Tract Diseases
Any liver or biliary tract disorder that results in the accumulation of bile salts in the skin may cause itching. Diseases with this affect include hepatic carcinoma, hepatitis, cirrhosis, obstruction of biliary ducts with gallstones, biliary atresia, and cancer.
4. Kidney Failure and kidney disease that results in uraemia (an increased urea level in the blood), and accumulation of urate crystals in the skin may cause itching.
5. The following autoimmune diseases are known to be accompanied by itching.
- Hashimoto’s thyroiditis
- Several types of Vasculitis
- Sjögren’s syndrome
- Systemic sclerosis
6. Malignant Diseases that cause itching:
- Acanthosis nigricans
- Acinic cell carcinoma
- Cancer of cervix
- Carcinoid syndrome
- Colon cancer
- Hodgkin’s lymphoma
- Melanoma and most other skin malignancies
- Non-Hodgkin’s lymphoma
- Paraneoplastic syndrome
- Polycythemia vera
- Prostate cancer
7. Central Nervous System Disorders
- Brain abscess
- Brain tumors
- Epidural anesthesia
8. Nutrient deficiencies such as iron and vitamin A may result in skin itching.
9. Hormonal Disorders
- Hyper/hypo-thyroidism, hyper/hypo-parathyroidism
- Last months of pregnancy (typically does not indicate any abnormality)
- Menopause (perimenopausal pruritus)
Itchy skin is often red and sometimes is accompanied by a rash, bumps, swelling, lumps or blisters.
What Can I Do?
So what can you do to get rid of itching? Let’s start with the simplest solution. Washing helps to relieve itching by getting rid of substances that irritate the skin. This is especially true after a sweaty work day or workout that produces excessive perspiration. It also helps with folliculitis, inflammation of a hair follicle.
Cooling the skin with ice cubs wrapped into a cloth and put over the itchy spot can help when the itching is caused by bacterial skin infection like folliculitis and contact dermatitis. You can avoid making the itch worse by not bathing in hot water, the excessive use of soap, and rubbing dry with towels. Instead of rubbing, pat the skin dry.
There are many over-the-counter moisturizing creams and ointments (odorless and colorless ones like glycerin, petroleum jelly, and mineral oil) that when applied right after bathing can also help relieve the itching of dry skin. You may also coat the area that itches with menthol, calamine, camphor, chamomile, or eucalyptus.
Medications for Itching
When the itching is caused by allergies, oral medications such as hydroxyzine, cetirizine, loratadine, or diphenhydramine may help. Creams containing antihistamines can cause an allergic reaction so you may want to avoid them. For an itch that is caused by inflammation corticosteroid creams can decrease the inflammation and reduce the itch. When large skin areas are affected, oral corticosteroids might also be used. For itching caused by fungal, parasitic, or bacterial infections, antimicrobial ointments, or antibiotics by mouth or injection may be required.
Sometimes treatment is not possible or required. In such cases waiting for the disease or irritation to heal by itself is often recommended. This may apply for:
- ciguatera poisoning
- contact dermatitis
- most viral skin infections
- staphylococcal or pseudomonas folliculitis
- viral hepatitis
Scratching an Itch
While scratching a minor itch can produce some relief, scratching can also irritate the skin and lead to more itching. Vigorous scratching can injure and may cause deep scrapes in the skin. In some people, even gentle scratching causes raised, red streaks that can actually increase the itch intensely. Avoid prolonged scratching and rubbing as this can thicken and scar the skin.
Note: Fingernails, especially children’s, can be kept short to minimize damage from scratching.