- Published on Wednesday, 22 June 2011 01:00
- Written by Patricia Wong, M.D.
There are few things in life more pleasurable than scratching an itch.
The causes of itching fall into several categories: dermatologic, neurologic and psychosomatic itching; itching due to underlying medical conditions, such as autoimmune disorders; connective tissue diseases; thyroid imbalance; lymphomas and cancers; drugs, including prescription and over the counter; and infection.
The dermatologic itch
A number of common skin conditions can contribute to itching, including dry skin, eczema, psoriasis and irritant or allergic dermatitis, from exposure to a variety of ingredients found in skin products to cleansing with harsh soaps.
By using appropriate emollients and gentle cleansers and becoming knowledgeable on which irritating contactants to avoid, one can effectively treat these itchy skin conditions.
When bathing, use a mild soap or liquid cleanser with a neutral or slightly acidic pH. Avoid triclosan-containing antibacterial soaps. Moisturize your skin two to three times per day with a cream-based, fragrance-free moisturizer. Creams are more moisturizing than lotions and contain fewer chemicals and preservatives.
Apply emollients within the first three minutes after bathing to seal in water that the skin has absorbed.
Have you been taking any new medications, vitamins, herbal supplements or laxatives? It is impossible to list all the medications that can induce itching, but the most recently introduced drugs are the most likely suspects – though it is possible to develop a hypersensitive reaction, presenting as itching, to a medication you have taken for a long period.
Itching as a symptom
Itching can be the first symptom of cancer or an underlying medical condition. Autoimmune diseases can be associated with widespread itching. Weakness, fatigue, arthritis, difficulty breathing or sun sensitivity accompanying generalized itching can be clues that an evaluation for an autoimmune condition is warranted.
A physician can order blood tests for specific autoantibodies associated with dermatomyositis, scleroderma, Sjögrens’s syndrome and other autoimmune disorders. These types of itching do not respond to antihistamine treatment.
Severe widespread itching can be the first symptom of a thyroid problem. An overactive thryroid (hyperthyroidism) or an underactive thyroid (hypothyroidism) can cause itching. The skin in hypothyroidism is extremely dry.
Liver and kidney diseases are also associated with generalized itching.
There is a type of skin cancer called cutaneous T-cell lymphoma that may present with generalized itching without any visible skin findings. A skin biopsy can reveal the presence of characteristic atypical T cells.
Hodgkin’s lymphoma can present as itching in affected lymph nodes triggered by drinking alcohol. Other medical conditions that affect the central nervous system, such as multiple sclerosis or strokes, can produce itching.
Many types of infections can cause itching, including parasites, viruses, yeast and fungus. Scabies is the most important one to diagnose and treat. The itching is worse at night and involves the genitalia, between fingers and toes, wrists, ankles, armpits, buttocks, elbows and breasts. If someone infected lives with others, everyone will become itchy. A skin sample examined under the microscope will show the presence of the mite, its eggs or fecal pellets and confirm the diagnosis.
Effective topical and oral medications for scabies are available.
All in the head?
Anxiety, stress and depression can be aggravating factors as well as consequences of itching. In more than two-thirds of patients with eczema, anxiety and depression play a major role in triggering itching’s severity.
Scratching can develop as a behavioral coping mechanism in response to feelings of hopelessness and loss of control. Scratching can be a way for people to relieve stress. When confronted with emotional stress or conflict, scratching the skin can become an automatic behavioral reflex.
Studies show that watching videos of people scratching will cause the majority of viewers to feel itchy and commence scratching. People under stress report more itching and develop a stronger itch-scratch cycle. Focus on reducing stress in your life.
Although scratching provides instant gratification, it ultimately causes permanent damage to the skin and underlying nerve fibers. The skin becomes thickened and discolored, and chronic scratching intensifies the itch sensation.
Injury to skin cells causes them to produce a substance called nerve-growth factor, which causes nerve fibers to sprout in the skin that heighten the itch sensitization. In the short term, scratching provides immediate relief, but ultimately, repeated scratching structurally damages the skin and intensifies the itching. This results in a vicious itch-scratch cycle that can be very resistant to treatment.
Persistent scratching damages not only the skin, but also the nerve fibers underneath the skin. Scratching just a few minutes each day for several weeks is sufficient to injure skin cells and create a chronic itching problem in previously normal skin.
Got an itch?
• Discontinue all skin-care products and use a bland cleanser that has no dyes or perfumes and few preservatives.
• Apply a cream-based moisturizer at least three or four times a day that has no fragrance or dye and few preservatives.
• Avoid scratching or rubbing the skin. Instead, gently slap, pinch or ice the area.
• Try an over-the-counter, nonsedating antihistamine such as loratadine or diphenhydramine (Benadryl) at bedtime.
• Eat a gluten-free diet for several weeks.
• Wear loose-fitting cotton clothing and avoid elastic or synthetic fabrics. No woolens. Wash all new clothing before wearing.
• A 1 percent hydrocortisone cream applied twice daily for a few weeks may help break the itch-scratch cycle.
• Practice relaxation or meditation techniques and reduce stress as much as possible.
• Know when to scratch and, more importantly, when to seek dermatological evaluation and advice.
Dr. Patricia Wong, a dermatologist in private practice in Palo Alto, specializes in cosmetic and medical dermatology. For more information, call 473-3173 or visit www.patriciawongmd.com.