Environmental Causes of Itchy Skin

1. Dry Skin

Dry skin (xerosis, winter itch) is common, especially in old people, and may be caused by cold weather, wind, sunburns, prolonged water exposure, frequent hot baths and using soaps (also washing powder and house cleansers) that can thin the protective oil layer on the skin and thus enable losing water through the skin.

2. Sweating

Microbes from normal skin flora break down the sweat (especially in armpits and groin) and yield substances that cause itching. Excessive sweating can be observed in persons with primary hyperhidrosis (increased activity of sympathetic nerves, possibly caused (but not confirmed) by psychological reasons), or secondary hyperhidrosis (e.g. in elevated thyroxine, tuberculosis, malignancies).

3. Insect Bites

Insects (mosquitoes, flies, tics, bees, wasps, ants, spiders, scorpions) bites may cause minor localized itchy and/or painful skin infection that usually heals on its own in several hours or few days. Some insect bites (especially bees) may cause severe allergic reactions with generalized skin itching and swelling.

4. Infections & Infestations

  • Fungi (e.g. Candida albicans) thrive well on feet and in moist body folds (groin, under breasts). Dandruff (scalp skin shedding and itching) is also caused by fungi. Athlete’s foot.
  • Parasitic skin infections (scabies, mites, lice, louse) are common. Cercarial dermatitis – itchy rash. Cutaneous larva migrans. Pets.
  • Intestinal worms may also cause skin itching.
  • Bacterial infections (Treponema pallidum) like infected acne are common in adolescents. Folliculitis caused by Staphylococcus aureus is common in athletes, impetigo is common in children. Hot tub folliculitis caused by Pseudomonas aeruginosa may arise after using non-properly treated pools or hot tubs. Read about other types of folliculitis.
  • Viral skin infections of childhood (measles, rubella, chicken pox, infectious mononucleosis) commonly result in itchy skin rash. Herpes labialis usually appears close to the mouth, Herpes genitalis on genital mucosa, and Herpes zoster over the course of cranial nerves on the head or spinal nerves on the trunk. Itching is common in AIDS. Viral hepatitis can also cause skin itching.
  • Hidradenitis suppurativa

5. Irritant Substances

Substances that may cause itching by irritating the skin (without causing skin inflammation)

  • Fiberglass used as insulation material (glass wool) can cause skin and throat itching
  • Detergents (washing powder) remove fat from the skin and thus dry it

6. Dermatitis

Dermatitis is non-infectious skin inflammation with red itchy rash, caused by touching, inhalation, or ingestion of certain substances (4).

  • Contact dermatitis can be allergic or non-allergic. It appears as sharply delimited red itchy skin area on the site of contact with wool clothes, necklesses, cosmetics, solvents…
  • Photodermatitis is a result of sunlight on chemicals (medications, cosmetics) in skin.
  • Generalized exfoliative dermatitis may be associated with use of some antibiotics, barbiturates, or by psoriasis etc.
  • Stasis dermatitis mostly occurs in patients with varicose veins on legs
  • Localized scratch dermatitis is localized skin inflammation due to long term scratching.
  • Benign mucosal pemphigoid – itchy blisters

7. Allergies

Allergic reaction toward certain substance can occur in minutes (early type) or from 6-72 hours after (late type of allergic response) contact with a triggering substance (allergen).

  • Food (and drugs) allergies commonly cause itching / tingling sensations around the mouth and in the throat. Facial skin and lips may swell.
  • Hay (pollen) allergies may cause difficulty breathing, runny nose, and skin and eyes itching.
  • Allergic contact dermatitis is caused by Urushiol contained in 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 – itchy rash
  • Hyperimmunoglobulin E (IgE) syndrome
  • Idiopathic hypereosinophilic syndrome – itchy skin

8. Adverse Effects of Medications

Several medications, chemotherapy and irradiation may cause skin itching.

9. Illegal Drugs and Itching

Cocaine, heroine, ecstasy and LSD abuse may all cause itching.

10. Poisoning

  • Alcoholic intoxication
  • Ciguatera poisoning, caused by ciguatoxin accumulated in some big tropical fish, may cause itching that lasts from few hours to several days or even months.
  • Acrodynia – severe itching caused by chronic mercury poisoning in infants in children
  • Vitamin A toxicity
  • Gold salts
  • Nicotinic acid
  • Fixed drug eruption

B. Systemic Diseases (Affecting the Whole Body) and Itching

1. Liver and Biliary Tract Diseases

Any liver or biliary tract disorder that result in bile salts accumulation in the skin may cause itching. Diseases include hepatitis, cirrhosis, hepatic carcinoma, obstruction of biliary ducts with gallstones, cancer, biliary atresia etc.

2. Gastrointestinal Diseases

  • Intestinal parasites. Parasites or their eggs in stool and bloating may accompany itchines.
  • Dumping syndrome
  • Malabsorption

3. Kidney Failure

Any kidney disease that results in uraemia (increased urea level in blood), and accumulation of urate crystals in the skin may cause itching.

4. Skin Conditions

  • Psoriasis
  • Rosacea
  • Lichen planus
  • In seborrheic dermatitis yellow, greasy scales appear on the scalp, face and occasionally on other areas from unknown reason
  • In nummular dermatitis coin-shaped eczema appears on the various parts of the skin
  • Perioral dermatitis mostly affects women between 20-60 years of age from unknown reason. Red rash appears around the mouth, nose and eyes.

5. Nutrient Deficiencies

  • Iron and vitamin A deficiency may result in skin itching.

6. Hormonal Disorders

  • Diabetes
  • Hyper/hypo-thyroidism, hyper/hypo-parathyroidism
  • Later months of pregnancy (usually does not indicate any abnormality)
  • Menopause (perimenopausal pruritus)

7. Autoimmune Diseases

  • Sjögren’s syndrome
  • Systemic sclerosis
  • Rheumatoid arthritis (and other types of arthritis)
  • Hashimoto’s thyroiditis
  • Vasculitis (several types)

8. Malignancies

9. Central Nervous System Disorders

  • Brain abscess, tumor or other disorders
  • Epidural anesthesia (when opioids are administered in lumbar part of the spinal canal to cause anesthesia of abdomen, back, buttocks and legs).

Symptoms Often Related to Itchy Skin

Skin redness, rash, swelling, bumps, blisters, or lumps are often associated with skin causes of itching, but rash can also appear in gut diseases like celiac disease, Crohn’s disease etc.

Diagnosis of Skin Itching

In skin diseases, a skin scraping, or skin biopsy in which a small piece of skin is surgically removed and investigated under microscope may be needed.
If an allergy is suspected, skin tests and blood tests (eosinophils – a type of white blood cell) may be performed.
If a systemic disease is suspected, blood tests are usually performed to check liver and kidney function, blood sugar, thyroxine, and parathormone levels etc.
Diet trials may reveal food intolerances or allergies. Temporarily discontinuation of medications may reveal drug side effects or allergies to certain drugs.

Treatment of Skin Itching

This is what you can do to get rid of itching:

Wash

Washing helps to relieve itching after:

  • an usual working day…
  • excessive perspiration
  • folliculitis
  • contact with certain irritant substances (washing won’t help if dermatitis has already developed)

Cool

Ice cubs wrapped into a cloth and put over the itchy spot can help in:

  • bacterial skin infection like folliculitis
  • contact dermatitis

Avoid bathing in hot water, excessive use of soaps, and rough drying with towels.

Try Remedies (Ointments)

Over-the-counter moisturizing cream (odorless and colorless ones like petroleum jelly, mineral oil, or glycerin) applied right after bathing can help relieve itching in dry skin (3).
Coating the affected area with menthol, camphor, chamomile, eucalyptus, or calamine may also help.

Take Medications

In allergies antihistamines by mouth (hydroxyzine, diphenhydramine, loratadine, cetirizine) may help. Creams containing antihistamines should be avoided, because they themselves can cause an allergic reaction.
In localized skin inflammation corticosteroid creams decrease inflammation. Low concentration corticosteroids, such as 1% hydrocortisone should be used to prevent thinning of the skin or side effects after absorption of corticosteroids into the blood. When large skin areas are affected, corticosteroids taken by mouth may be used.
In fungal, parasitic, or bacterial infections, antimicrobial ointments, or antibiotics by mouth or injection may be required.

Treat the Cause

The cause of the itchiness may be usually successfully treated in bacterial, fungal infections and parasites. Kidney diseases and even several cancers can be successfully treated.

Wait and Prevent

Sometimes treatment of the cause is not possible, or not needed, so waiting that the disease heals by itself and prevention of its re-occurrence is recommended. This may apply for:

  • most viral skin infections
  • staphylococcal or pseudomonas folliculitis
  • viral hepatitis
  • contact dermatitis
  • allergies
  • ciguatera poisoning

Scratching

Scratching can irritate the skin and lead to more itching. Vigorous scratching may cause deep scrapes in the skin. In some people, even gentle scratching causes raised, red streaks that can itch intensely. Prolonged scratching and rubbing can thicken and scar the skin. Fingernails, especially children’s, should be kept short to minimize abrasions from scratching.

Localized Itch

Itch can be generalized (itching all over) or can affect only limited parts of skin or mucosa:

Further Reading:

References:

  1. Itching (pruritus) definition (cancer.gov)
  2. Prurireceptors (healthatoz.com)
  3. Causes of itchiness (merck.com)
  4. Dermatitis (merck.com)
  5. Medications for itch (pubmed.gov)
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Further Reading :
  • Itchy Rectum and Anus – Causes and Treatment
  • Diarrhea & Skin Rash, Itch, Tingling, Jaundice or Swelling
  • Itchy Rash
  • Types of Skin Cancer – Pictures and Treatment
  • Sunburn Itch – Prevention and Treatment