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Irritant and allergic contact dermatitis

Key learning points:

- Common types of contact dermatitis

- Diagnosing dermatitis and identifying allergens

- Assessment and management principles of contact dermatitis

The words 'eczema' and 'dermatitis' are used interchangeably to describe patterns of inflammation in the skin which can be acute or chronic. Acute dermatitis presents with erythema (redness) and vesiculation (blistering), and chronic dermatitis with dryness, lichenification (skin thickening) and fissuring (splitting).1 Contact dermatitis refers to these reactions following contact with substances on the skin2 and accounts for 4-7% of dermatology consultations.3 Contact dermatitis can be classified into several types (see Box 1). Contact irritant and allergic dermatitis will be discussed within this article.

Irritant contact dermatitis

Irritant contact dermatitis is commonly caused by repeated exposure to weak irritants:

- Wet - such as water, soaps, detergents, solvents, weak

- Dry - in low humidity, heat, air and dust.1 This results in damage to the epidermal barrier, and the cumulative skin irritation, inflammation and damaged skin barrier all provide ideal conditions for sensitisation and allergic contact dermatitis.4 (See Figure 1).

Contact allergic dermatitis

Allergic contact dermatitis is a delayed hypersensitivity reaction (type IV delayed hypersensitivity) and is the result of absorption of an allergen into the skin that evokes an immune response, which is remembered on subsequent allergen exposures.5 (See Figure 2).


Clinically, it is difficult to differentiate between irritant and allergic contact dermatitis and endogenous eczema, particularly with hand eczema. Clinical features and history (see Box 2) in isolation are unreliable. Patch testing is an essential investigation in patients with persistent eczematous eruptions when contact allergy is suspected or cannot be ruled out.3 Patch testing involves the reproduction under the patch tests of allergic contact dermatitis in an individual sensitised to a particular antigen(s). It involves the application of antigens to the skin at standard concentrations in an appropriate vehicle and under occlusion for 48 hours before removal, with a final reading at 96 hours. The reading will assess whether the reaction is a true allergic reaction or an irritant reaction.2 A standard series of allergens (British Contact Dermatitis Society standard series) and ones specifically relevant to the patient (such as the British Contact Dermatitis Society hairdressing series) are used.3 Occupations that have an increased risk of contact dermatitis include the following examples: building workers, caterers, cooks, cleaners, hairdressers, metal workers.

Management Principles

Irritant contact dermatitis

The management of irritant contact dermatitis involves the protection of the skin from irritants, water, soaps and detergents, and in the workplace irritants such as oils, coolants, alkalis, acids and solvents need to be considered.3

- Avoidance: avoiding products is obvious, but workplace visits can also be beneficial.

- Protection: as hands can be the main problem, gloves are the mainstay of protection. The type used and the use of cotton liners will be dependent on the task they are used for. It is important to take gloves off at regular intervals as sweating may aggravate existing dermatitis.3

- Substitution: to non-irritating agents, commonly using a soap substitute instead of soaps and detergents.

Allergic contact dermatitis

The management of allergic contact dermatitis involves the above, avoidance, protection and substitution, however detection and avoidance of the allergen can be challenging. It may be necessary to contact manufactures of products to determine if the allergen is present and also to contact others to identify suitable substitutes.3

Hand care

Hand care for contact dermatitis includes:

- Skin inspection: regular checking, covering cuts.

- Hand washing: wash in warm water, unperfumed soap or soap substitute, rinse

hands thoroughly, dry carefully and apply moisturiser (no perfume or lanolin).

- Gloves: wear gloves to protect hands from cold weather, wet work and contact with substances irritant to the skin, such as shampoos, detergents, polishes, solvents, cleaning agents, stain removers and when preparing food such as citrus fruit, potatoes and tomatoes.

- Jewellery: remove rings, especially before washing hands.2


Topical medication

Barrier creams alone are of questionable value in protecting against contact with irritants and may confer a false sense of security. After-work creams/emollients should therefore be encouraged in the workplace and be readily available.3

Emollients and soap substitutes soothe, smooth and hydrate the skin and are indicated for all dry or scaling disorders. Their effects are short-lived and they should be applied frequently even after improvement occurs. With a damaged skin barrier associated with irritant/contact dermatitis, applying an emollient provides a surface film of lipids and restores/protects the barrier function.

Topical corticosteroids are effective in reducing inflammation. They should only be used intermittently to treat flares of dermatitis and the least potent corticosteroid preparation that controls the dermatitis should be used. While it is important that patients use enough steroid to control their condition, applying them in the smallest amounts, and for the shortest possible time, will minimise the risk of side-effects.6 The amounts used and potency of the steroid should be evaluated in order to monitor efficacy.

Second-line treatments

Specialist second line therapies include psoralen plus UVA, azathioprine and ciclosporin. Oral retinoids (alitretinoin) are also used for chronic hand dermatitis.3


Contact dermatitis (irritant and allergic) has an impact on all aspects of daily living at home, work, school and leisure time. Contact dermatitis is not associated specifically with occupational causes in isolation, and many activities which are deemed normal everyday activities can contribute to irritant/contact dermatitis. Housework, DIY, hobbies, sports and extremes of weather can potentially play a part.


DermNet NZ

British Association of Dermatologists

National Eczema Society

British Dermatological Nursing Group

Allergy UK


1. Gawkrodger DJ. Workplace dermatitis. Mims Dermatology 2010;6(2):13-6.

2. Lawton S, Gill M. Contact dermatitis: types, triggers and treatment strategies. Nursing Standard 2009;23(34):40-6.

3. Bourke J, Coulson I and English J. Guidelines for the management of contact dermatitis: an update. British Journal of Dermatology 2009;160:946-54.

4. Smith HR, Armstrong DKB, Holloway D, Whittam L, Basketter D, McFadden JP. Skin irritation thresholds in hairdressers: implications for the developments of hand dermatitis. British Journal of Dermatology 2002:146(5):849-52.

5. Jacob SE, Steele T. Allergic Contact Dermatitis: Early recognition and diagnosis of important allergens. Dermatology Nursing 2006;18(5):433-46.

6. Lawton S. Safe and effective application of topical treatments to the skin. Nursing Standard 2013;27(42):50-8.