Trigger factors should be identified and avoided or appropriately managed. These can include irritants such as detergents and soaps, extremes of temperatures and humidity, wool and synthetic fabrics, infection and allergens. Allergens can be environmental (including airborne and contact allergens) or ingested food allergens.
Food allergens as a trigger for eczema should be considered when a patient experiences an immediate IgE mediated reaction to a food. A non-IgE mediated allergy should be considered in young children and infants with moderate to severe eczema that is unresponsive to optimum therapy, particularly if there is growth failure or an association with gastrointestinal symptoms that also fail to respond to standard therapy.7
Routine allergy investigations such as skin prick testing and specific IgE testing often yield inconclusive results in non-IgE mediated conditions. A carefully managed limited therapeutic trial of food elimination and reintroduction may be diagnostic. The maternal diet should also be assessed where a baby is breastfed, as maternally ingested allergen can enter breastmilk, affecting the infant. Dietary manipulations need to be carefully managed and overseen to avoid nutritional deficiencies arising from unnecessary or prolonged dietary eliminations in both the infant and their mother.
The BSACI and industry-led guidelines outline the management of non-IgE mediated cows milk allergy associated with eczema:8 https://www.bsaci.org/guidelines/bsaci-guidelines/cows-milk-allergy/
Treatment should be tailored to the needs of the patient and can be stepped up or down according to need. A clear explanation accompanied by a written management plan and an eczema education programme are key adjuncts to effective management.
There are 2 main aims of topical therapy: Moisturisers to restore the skin barrier and anti-inflammatory agents to combat inflammation.
Moisturisers are the cornerstone of therapy and are useful against xerosis and transepidermal water loss. They can also be used for washing and bathing in lieu of soaps and detergents.
Moisturisers should be applied liberally and frequently. Children require 250–500 g weekly and the average adult requires at least 840 g a month for once daily application.9
There is a large array of moisturisers with varying properties to suit different patients. They can be emollient to lubricate and soften the skin, occlusive to reduce water evaporation and humectant to attract and hold water in the skin.
In the UK, these encompass topical steroids and topical calcineurin inhibitors.
Topical steroids: 9
Topical steroids are anti-inflammatory and immunosuppressive. They can be classified as mild, moderate, potent and very potent (according to their ability to cause vasoconstriction and inhibit inflammation). The choice of topical steroid is determined by the location and severity of the eczema and the lowest effective potency should ideally be used. The ‘fingertip unit’ method can help patients estimate the appropriate amount to use.
Use is recommended once (or twice) daily, with little evidence that twice daily dosing is more advantageous. The NICE guidelines for the frequency of application of topical steroids can be found here: https://www.nice.org.uk/guidance/ta81/chapter/1-Guidance
Topical steroids come in different formulations. Ointments are in general more effective than creams as they are occlusive, enhancing penetration. They contain fewer preservatives, reducing the risk of irritation and allergy.
Side effects are unusual with low potency preparations. More potent preparations need to be used with caution. They can be associated with skin atrophy and caution should be exercised on areas where the skin is already thin, such as on the face and in the flexures. Other side effects include hypopigmentation, secondary infection, acne, striae and bruising.
Topical calcineurin inhibitors: 9
The NICE guidelines for the use of topical calcineurin inhibitors can be found here: https://www.nice.org.uk/guidance/cg57/chapter/1-Guidance
Topical calcineurin inhibitors (pimecrolimus and tacrolimus) are also anti-inflammatory and immunosuppressant and can be used as an alternative to topical steroids. They are not associated with skin atrophy, adrenal suppression, and other systemic side effects of topical steroids and as such, are a useful adjunct for the face, eyelids and other delicate areas of skin. Acute flares of eczema may need to be controlled with moderate-to-potent topical corticosteroids for 3 to 5 days before stepping down to a calcineurin inhibitor, and clinical infection at the site should be treated before topical calcineurin inhibitors are used.
There are 2 preparations. Tacrolimus ointment is more potent than pimecrolimus cream.
Tacrolimus is available as an ointment in two strengths (0.1% and 0.03%). The 0.03% strength is licensed for treatment from 2 years of age and the 0.1% strength is licensed from 16 years of age, to treat moderate to severe atopic eczema in patients who have not adequately responded to, or are intolerant of, conventional therapies.
Pimecrolimus is available as a 1.0% cream and is licensed for mild to moderate atopic eczema from the age of 2 years.
Proactive versus reactive application of topical anti-inflammatory agents:
Traditionally anti-inflammatory agents were employed reactively in response to visible eczema. In contrast, medium term clinical trials have demonstrated that proactive use of anti-inflammatory therapy, can lead to overall improvement, fewer exacerbations and improved quality of life. In practice, this comprises the use low-to-moderate potency steroids or topical tacrolimus 2 or 3 times weekly to areas of subclinical inflammation persisting at skin sites previously affected by eczema.
Cleansing and bathing:10
The skin must be cleansed gently and thoroughly to eliminate debris and bacterial contaminants. Baths of short duration (5 minutes) and bath oils aim to avoid epidermal dehydration. Topical emollients should be applied directly after a bath or a shower after gentle drying when the skin is still slightly damp.
Sodium hypochlorite added to the bathwater (‘bleach baths’) may be considered because of its antiseptic properties.
The majority of patients with eczema are colonised by Staph aureus and are also susceptible to secondary skin infections. Systemic antibiotics may be required to treat bacterial skin infections, and the choice of antibiotic should be based on bacterial sensitivities. Staph aureus is a common cause of eczema flares in children.
Systemic management and Emerging therapies:
Patients with severe eczema, unresponsive to optimum topical therapy, may be candidates for systemic immunosuppression under the supervision and monitoring of specialist dermatologists. Drugs in this category include ciclosporin, oral corticosteroids, azathioprine and methotrexate.
Monoclonal antibody therapies that have emerged into clinical use targeting IL4 and IL13 of the Th2 pathway. It is approved for use for eczema from the age of 12 years old in the USA. In 2019 it has Marketing Authorisation in the European Union (EU) and is licensed in the UK for adults with moderate to severe eczema. It is approved by NICE for use in adults with moderate to severe eczema that has not responded to at least 1 other systemic therapy. (https://www.nice.org.uk/guidance/ta534/chapter/1-Recommendations). The application for use in childhood eczema in the EU and UK are in progress.
A host of other targeted and broad-acting systemic therapies are currently being investigated for use in eczema.
Crisaborole is a topical phosphodiesterase 4 inhibitor approved by the FDA in the USA for patients aged from 2 years with mild to moderate atopic dermatitis. It has yet to receive UK or EU approval.