Dermatitis

Dermatitis is a broad term that refers to a group of inflammatory skin diseases that cause itching, redness, and rash. Treatment involves self-care and application of prescription creams or ointments to control the symptoms.

General information

Dermatitis is inflammation of the skin, which can take different forms and have different causes. Common types of dermatitis are:

• Eczema (also known as atopic dermatitis): A long-lasting form of dermatitis that is common in childhood and tends to run in families
• Contact dermatitis: A short-lasting dermatitis that is triggered by exposure of the skin to certain substances
• Seborrhoeic dermatitis: A common dermatitis that primarily affects the scalp and face.

Other less common forms of dermatitis include:

• Discoid (or nummular) dermatitis, which may be due to having particularly dry skin or triggered by injury to the skin
• Infective dermatitis, which is triggered by a bacterial or fungal infection
• Varicose (or gravitational) dermatitis, which develops on the lower legs of elderly people due to increased pressure in the leg veins.

Dry skin is a common skin problem (particularly among older people) caused by a lack of moisture in the skin; it can be associated with various forms of dermatitis.

Dermatitis differs from psoriasis, which is chronic inflammatory skin disease caused by an immune system problem that results in the over-production of skin cells.

Skin affected by eczema may be more vulnerable to infections such as warts, cold sores and athlete's foot. Eczema is also associated with keratosis pilaris - a harmless skin condition that involves the appearance of numerous small, rough bumps on the skin.

Causes

A range of factors can cause different types of dermatitis.

• Eczema is likely related to a combination of things, including dry skin, genetics, immune system dysfunction, bacteria on the skin, and environmental conditions
• Contact dermatitis is due to direct contact with an irritant substance or allergen, e.g. nickel in jewellery, ingredients in skin cleansing products, perfumes, and cosmetics
• Seborrhoeic dermatitis may be caused by oily skin or by substances produced by yeasts (fungus) that live on the skin.

Risk factors

Several factors can increase the risk of developing dermatitis:

• Age: Although dermatitis can occur at any age, eczema usually first develops during infancy
• Allergies and asthma: People who have a personal or family history of eczema, allergies, hay fever, or asthma are more likely to develop eczema
• Occupation: Jobs in which the skin is exposed to certain metals, solvents, or cleaning products increase the risk of developing contact dermatitis
• Certain health conditions: People with congestive heart failure, Parkinson's disease, and HIV/AIDS may be at increased risk of developing seborrhoeic dermatitis.

Psychological stress or anxiety can aggravate existing dermatitis, probably by affecting how the body’s immune system works.

Signs and symptoms

The different types of dermatitis differ in appearance and tend to occur on different parts of the body.

• Eczema: Dry, itchy, red rash, which when scratched causes fluid to leak and crust over. It most commonly affects the face and the skin creases on the inside of the elbows and behind the knees. It will usually go through phases of remission and flare up.
• Contact dermatitis: A red rash that may burn, sting or itch, and blister. It affects areas of the body exposed to substances that either irritate the skin or cause an allergic reaction.
• Seborrhoeic dermatitis: Scaly patches, red skin, and significant amounts of dandruff. It usually affects the scalp but also oily areas of the body, e.g. face, upper chest, and back. It can be a long lasting condition with phases of remission and flare-ups. In infants, seborrhoeic dermatitis is known as cradle cap. Blepharitis (scaly red eyelid margins) is a common feature of seborrhoeic dermatitis.

You should consult a GP if you or your child’s dermatitis becomes painful, shows signs of infection (i.e. weeping, crusting, small pus-containing bumps), causes loss of sleep, or makes performing daily activities difficult.

Diagnosis

A GP can usually diagnose dermatitis by asking about your signs and symptoms and examining your skin.

Laboratory tests are not required to diagnose dermatitis but patch testing (skin allergy tests) may be conducted if contact dermatitis is suspected.

Patch testing involves the application of small amounts of various known substances to your skin under an adhesive covering. After several days, the skin is examined to see if there has been a reaction to any of the substances. Patch tests are not the same as skin prick tests, which are used to diagnose hay fever allergy.

Treatment

Treatment for dermatitis depends mainly on the cause. In addition to self-care (see below), most dermatitis treatment plans include one or more of the following:

• Application of prescription corticosteroid creams, to help settle inflammation
• Application of prescription creams that modify immune system function (calcineurin inhibitors)
• Phototherapy, which involves exposing the affected areas to controlled amounts of natural or artificial light
• Antibiotics if there is bacterial infection of the skin
• Antihistamine tablets, which may help to reduce itching.

Self-care

The following life style changes and home remedies can help control symptoms:

• Using non-prescription anti-inflammatory and anti-itch products (e.g. low-potency hydrocortisone cream or calamine lotion)
• Taking a non-prescription oral antihistamine if itching is severe
• Applying cool wet compresses to affected areas will help to soothe the skin
• Covering itchy areas with a dressing to prevent it from being rubbed or scratched
• Keeping nails trimmed and wearing gloves at night to minimise the effects of scratching
• Wearing smooth-textured cotton clothing to avoid irritating affected areas
• Washing clothes, sheets, and towels using mild non-fragranced washing powders or liquids
• Avoiding irritants and in cases of contact dermatitis especially, try to minimize contact with the substance that causes the rash
• Wearing cotton gloves under rubber gloves when cleaning or washing the dishes
• Learning stress-management techniques (relaxation, yoga, meditation, mindfulness) to control stress and anxiety, which can trigger flare-ups
• For seborrhoeic dermatitis, use pharmacy shampoos that contain coal tar, ketoconazole, zinc pyrithione, selenium sulphide, or salicylic acid.

Prevention

Preventing skin becoming dry may help avoid the development of dermatitis. For example:

• Apply fragrance-free moisturiser daily
• Take shorter baths or showers (5–10 minutes only) and use warm, rather than hot, water
• Use non-soap cleansers or mild soaps (ideally varieties that are fragrance-free)
• After bathing or showering, gently pat the skin dry with a soft towel, and while the skin is still damp, seal in the moisture with a moisturiser
• Take a moisturising bath by sprinkling (warm not hot) bath water with uncooked oatmeal or colloidal oatmeal (finely ground oatmeal), soaking for 5–10 minutes, patting the skin dry, and then applying moisturiser.

References

Cleveland Clinic (2015). Dermatitis (Web Page). Cleveland: Cleveland Clinic. https://my.clevelandclinic.org/health/articles/4089-dermatitis [Accessed: 26/07/18]
Mayo Clinic (2016). Dermatitis (Web Page). Rochester, NY: Mayo Foundation for Medical Education and Research. https://www.mayoclinic.org/diseases-conditions/dermatitis-eczema/symptoms-causes/syc-20352380 [Accessed: 26/07/18]
Ministry of Health (2018). Eczema (Web Page). Wellington: New Zealand Government Ministry of Health. https://www.health.govt.nz/your-health/conditions-and-treatments/diseases-and-illnesses/eczema [Accessed: 26/07/18]
Oakley, A. (1997). Dermatitis (Web Page). Hamilton: DermNet New Zealand. https://www.dermnetnz.org/topics/dermatitis/ [Accessed: 26/07/18]

Updated: July 2018

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