What Causes the Itch and Scratch Cycle of Eczema?
Itch is perhaps the most common and distressing symptom experienced by people with eczema. The itch-scratch cycle of eczema is a complex phenomenon that involves the interplay of three major parts:
1) Heightened sensation to itch stimuli
2) A reflex-like response to itch
3) Emotional reward of pleasure and stress-reduction after scratching.
More Sensitive to Itch Stimuli
People with eczema have a heightened sensitivity to “itchy stimuli”. A simple touch, a brush by the clothing fabric, sweating, or even a sudden temperature change can lead to intense itching. Itchiness experienced by people with eczema can be tormenting and is fueled by the psychological urge to scratch.
There is Pleasure in Scratching
Scratching is a natural response to itch. Studies have shown that “scratching the itch” can be highly pleasurable. In fact, the pleasure centers in the brain light up when people scratch their itchy skin.[2,3] This rewarding sensation feeds on more scratching behavior. In our nervous system, the message for itch sensation is carried by the same nerve fibers that carry pain stimuli, so some experts believe that itch is actually a type of pain.[2,3] Our nervous system responds to chronic itch by producing a subconscious “scratch reflex.” As a result, the itch sensation is replaced by a slightly painful sensation from scratching.
The end result of repetitive scratching can be emotionally and physically detrimental, and include:
- Social embarrassment from the appearance of scratched skin and preoccupation with scratching in public, scratching.[5,6]
- Scratching induced damage to the skin’s protective barrier, causing microscopic cracks on the top layers of the skin, making the skin “leaky”. The damaged skin barrier has a harder time retaining moisture and allows water to evaporate easily, and the skin dryness further adds to itchy skin.
- The “leaky skin” also allows irritating chemicals, allergens and even bacteria such as Staphylococcus aureus to enter the skin more easily, which leads to more skin inflammation and more intense itch.[8,9] These components together drive the vicious itch-scratch cycle.
How Can We Break This Cycle?
Interventions targeting any of the points in the itch-scratch cycle can essentially help to break it.
- The skin barrier may be repaired by frequent use of moisturizers to help keep the skin hydrated.
- Skin inflammation can be treated with topical steroids or calcineurin inhibitors.
- Skin infections can be treated with topical or oral antibiotics and bleach bath.[10,11]
- Habitual training, behavior modification and biofeedback therapies may help manage the scratch behavior.[12,13] These treatments can help people with eczema become more aware of their repetitive scratching behavior and offer alternative ways to combat the urge to scratch.
- Lastly, certain psychiatric and mood-modulating medications may help to decrease both the itching sensation and obsessive-compulsive scratching behaviors.[14,15]
Cutting your fingernails short may help minimize damage to the skin during scratching. Often times people scratch in their sleep subconsciously, so wearing cotton gloves for children and adults, or scratch mittens for babies may be helpful.
Please consult a healthcare professional regarding ways to diagnose the cause of your itch and for help with evaluating itch related symptoms.