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The ‘itch cycle’

21 November 2013

The itch: A hallmark of eczema

An itch is defined in the dictionary as ‘an irritating skin sensation causing a desire to scratch’ and is often referred to by its Latin name, ‘pruritus’.

Medicines, disease, infections, insect bites, irritants or dermatological disorders such as eczema can cause an itch. In eczema, the itching sensation is one of the most prominent and distressing features of the condition.1 And, it is easy to understand why this is especially true for children.

Indeed, the itch can be considered to be a hallmark of eczema. It can be intense, painful, disrupt sleep and have a significant impact on the quality of life for eczema patients.2

The ‘itch cycle’

An itch originating in the skin creates a scratch reflex, which draws attention to the affected site, and scratching is generally regarded as a way to reduce/relieve the annoying itch sensation. Thus, the most characteristic response to itching is the scratch reflex; an almost in-voluntary and often sub-conscious activity, especially in children.1

Patients feel severe itch and cannot refrain from scratching. Scratching worsens the dermatitis and creates more itch resulting in an ‘itch-scratch’ cycle.2-4

What causes the eczema itch?

A wide range of stimuli are able to trigger the itch, one of these being histamine.1 Scientific experiments have shown that histamine (one of the chemicals that is released in the body as part of an allergic reaction) plays a key role in the eczema itch and this is reflected by the history of antihistamines in the treatment of eczema.1

The mechanisms responsible for the itch are highly complex; intricate biochemical pathways involving the release of various inflammatory mediators leads to up regulation and activation of neuropeptides (small protein-like molecules used by neurons to communicate with each other) within itch receptors in injured or inflamed skin.2,5

Role of the nervous system in the eczema itch

Itch receptors are only found in the top two layers of skin and as a result an itch is only ever felt on the skin and never felt in muscle, joints, or internal organs.5

Nerve fibres for itch which carry the itch sensation to the brain originate in the skin, and scientific studies have shown that the involuntary nervous system mediates and contributes to the itch in eczema patients.3 Chronic itch may therefore be treated with therapies that can modulate the involuntary nervous system stress response.3

Treating the eczema itch

Itching significantly impacts and lowers the quality of life for eczema patients. Relief from itching is therefore one of the most important goals in the treatment of eczema.6

Standard management techniques include the removal of causative and exacerbating factors, appropriate skin care and drugs to relieve the itch.6

Causative and exacerbating factors for itch include sweat, heat, clothing, detergents and stress. In children, eczema is sometimes complicated by food allergies, which are high risk factors for the appearance of eczema.6

It is important that your child avoids environmental allergens, irritants and other flare triggers. Keep your child cool as higher body temperatures can make eczema itch more and cover the itchy area if your child can’t stop scratching. Wearing cotton clothing, natural fibres or biofunctional garments such as imuDERM will help your child avoid contact with irritants, keep cool, feel more comfortable and will help to stop your child scratching.

Eczematous skin has a tendency to become dry and dry skin lowers the threshold of itching. Emollients are lotions, creams, ointments and bath/shower additives that prevent the skin from becoming dry. They help the skin retain moisture keeping it supple and moist, help to protect the skin from irritants and provide symptomatic relief from the itch.4,7 The regular use of emollients is the most important part of day-to-day eczema treatment.4,7,8

One of the simplest and most straightforward ways to relieve the eczema itch is the application of ice or a cold-water compress. 7-9 However this can offer only short-term symptomatic relief as it can stop the itch only for as long as the ice or cold water is applied.7-9

Antihistamines are a large group of drugs that have a similar anti-itch effect and are prescribed to the vast majority of eczema patients.1 Although ‘first-generation’ antihistamines are effective in reducing the itching caused by insect bites etc., they are of limited use in relieving the persistent itching from eczema.6 However, ‘second-generation’ antihistamines are effective in decreasing the severity of the eczema itch and are less sedative compared to first-generation agents.6

A variety of over-the-counter and prescription anti-itch drugs are available. Topical agents, which are applied directly to the skin in the form of creams and sprays, are often available over-the-counter whilst oral anti-itch drugs are usually prescription drugs.7-9 The active ingredients usually belong to the following classes: 7-9

·         Antihistamines

·         Topical steroids

·         Local anaesthetics

·         Counterirritants, such as mint oil, menthol, or camphor

Scratching and the risk of infection

Although, it is very difficult to avoid, scratching the skin can make the itch worse and eczema patients are highly susceptible to certain cutaneous bacterial, fungal and viral infections.10

Bacteria, especially Staphylococcus aureus a natural member of our skin flora, can easily enter the body through broken skin and establish an infection.10 Staphylococcus aureus is the most common skin infection in eczema patients and occurs in more than 90% of eczema patients compared to 5% of normal individuals.10

Eczema patients are susceptible to severe infections caused by herpes simplex type 1 virus, vaccinia virus, coxsackie A virus and molluscum contagiosum. These infections can represent serious complications in eczema patients and if not treated quickly have the potential to be life threatening.10

Breaking the ‘Itch-scratch-cycle’

It is important to understand that the act of scratching provides the eczema patient with a degree of short-term relief from the chronic itching. However one of the most difficult, but most important things to do in eczema is to break the itch-scratch cycle; especially in children.

It can be helpful if a parent/carer monitors the child and when they notice scratching, gently provide verbal or physical reminders to stop. This will not only make the child pause and think about not scratching, but actually notice that they were about to scratch. It can also be helpful to redirect their attention, gently take their hand or point out not to scratch.

Keep a record of times and situations when scratching is worst and try to limit your child’s exposure to such situations. Many children with eczema scratch most during idle times. Engaging in a structured activity with other people or keeping busy with activities that involve the use of their hands may help prevent scratching.

Other approaches could include meditation or cognitive behavioural therapies and some chronically affected children may benefit from expert assistance such as a brief consultation with a psychologist.

Stop the scratch

·         Trim the fingernails as short nails are less likely to damage skin

·         Cover the itchy area if your child can’t stop scratching it. Wearing cotton clothing, natural fibres or biofunctional garments such as imuDERM will help to stop your child scratching and feel more comfortable

·         Avoid environmental allergens, irritants and other flare triggers. Wearing loose cotton clothing, natural fibres or biofunctional garments such as imuDERM will help your child avoid contact with irritants and feel more comfortable

·         Keep cool as higher body temperatures can make eczema itch more. Wearing loose cotton clothing, natural fibres or biofunctional garments such as imuDERM will help your child to keep cool and feel more comfortable, especially in bed

·         Ensure your child drinks plenty of fluid to stay hydrated

·         Ensure your child regularly applies liberal amounts of emollient

When the itch just won’t stop

Everyone itches. It is normal. People can usually ignore the sensation, although adults are better at this than children.

An itching child can be a real problem as children are particularly prone to scratching and the itching associated with eczema can be very frustrating for you and your child. However, there are things you can do to give you and your child some relief. Wearing cotton clothing, natural fibres or biofunctional garments such as imuDERM will help your child avoid contact with irritants, stop your child scratching and he/she will feel more comfortable.

Support groups and online support forums can be a great help and the National Eczema Society is an excellent source of information and provides resources online and through its helpline.

National Eczema Society www.eczema.org Helpline: 0800 089 1122 helpline@eczema.org

ImuDerm and CliniSupplies are supporters of The British Skin Foundation.

The British Skin Foundation http://www.britishskinfoundation.org.uk/

References:

1.      Buddenkotte J, Maurer M, Steinhoff M. Histamine and Antihistamines in Atopic Dermatitis. Adv Exp Med Biol. 2010;709:73-80.

2.      Yosipovitch G, Papoiu AD. What causes itch in atopic dermatitis? Curr Allergy Asthma Rep. 2008;8(4):306-11.

3.      Tran BW, Papoiu AD, Russoniello CV, et al. Effect of itch, scratching and mental stress on autonomic nervous system function in atopic dermatitis. Acta Derm Venereol. 2010;90(4):354-61.

4.      Leung DYM. Chapter 139 - Atopic dermatitis (atopic eczema). In Kleigman: Nelson textbook of paediatrics. 19th Ed. Saunders, 2011.

5.      Vinik AI. Barely scratching the surface. Diabetes Care. 2010 Jan;33(1):210-2.

6.      Yamashita H, Tanaka H, Inagaki N. Treatment of the chronic itch of atopic dermatitis using standard drugs and kampo medicines. Biol Pharm Bull. 2013;36(8):1253-7.

7.      Caring for children and young people with atopic eczema: Guidance for nurses. Royal College of Nursing. April 2013. Available online at http://www.rcn.org.uk/

8.      Atopic eczema in children. National Institute for Health and Clinical excellence (NICE) clinical guideline 57. Quick reference guide. December 2007. Available online at http://www.nice.org.uk/

9.      NHS choices. Itching – treatment. Available online at http://www.nhs.uk/Conditions/Itching/Pages/Treatment.aspx

10.  Baker BS. The role of microorganisms in atopic dermatitis. Clin Exp Immunol. 2006;144(1):1-9.

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