Dermatitis Knowledge Academy

Dermatitis is a condition that causes inflammation of your skin. One of the causes could be through contact. There are two types - Allergic and Irritant.

Allergic contact dermatitis - this type of dermatitis is caused by an allergin . An allergen is a substance which causes your immune system (which normally fights illness and infection) to react abnormally. Your immune system is your body's defence system, which help to protect you from disease, bacteria and viruses.
When you are exposed to an allergen for the first time, you become sensitised to it. After that, every time you have contact with the allergen, it causes a reaction.

Irritant contact dermatitis - this type of dermatitis is caused by contact with an irritant. An irritant is a substance that damages the skin, causing it to be inflamed. It can occur in anyone who is exposed to irritants for a sufficient amount of time.

Some substances act both as allergen and irritant (wet cement, for example). Other substances cause a problem after sunlight exposure, bringing on phototoxic dermatitis.
Around three quarters of all cases of contact eczema are of the irritant type, which is the most common occupational skin disease. Contact eczema is curable provided the offending substance can be avoided, and its traces removed from one's environment.

Contact dermatitis is a localised rash or irritation of the skin caused by contact with a foreign substance. Symptoms include your skin becoming red, blistered, dry or cracked even. Only the superficial regions of the skin are affected in contact dermatitis. Inflammation of the affected tissue is present in the epidermis (the outermost layer of skin) and the outer dermis (the layer beneath the epidermis).
Unlike contact urticaria , in which a rash appears within minutes of exposure and fades away within minutes to hours, contact dermatitis takes days to fade away.
Contact dermatitis fades only if the skin no longer comes in contact with the allergen or irritant.
It can result in large, burning, and itchy rash, and it can take anywhere from several days to weeks to heal. Chronic contact dermatitis can develop when the removal of the offending agent no longer provides expected relief.

Irritant contact dermatitis
Irritants cause approximately 80 per cent of cases of contact dermatitis. An irritant reaction is caused by the direct effect of an irritant substance on the skin. An irritant substance is one that would cause an inflammatory reaction in most individuals when applied in sufficient concentration for an adequate amount of time.
Irritants cause direct injury to the skin. This can occur over a short (acute) or long (chronic) period of time.
A single exposure to a substance can cause an acute dermatitis, within minutes to hours after exposure.
Chronic irritant contact dermatitis is due to multiple exposures, often to several irritants at low levels over time. This dermatitis can take many months or years to appear.

Irritants are often encountered at work (occupational) although other common irritants are soaps, detergents, food and cement. Almost all workers in wet-work industries, such as hairdressing, cleaning, metal engineering, building-site work and horticulture develop some degree of irritant contact dermatitis.
An irritant dermatitis is most likely to occur on the hands.
Strong concentrations of irritants cause an acute effect, but this is not as common as the accumulative, chronic effect of irritants whose harmful effects build up with subsequent doses.

The effects can include inflicting damage to the barrier properties of the epidermis and causing the layer to thin and increasing the transepidermal water loss.
Transepidermal water loss is defined as the measurement of the quantity of water that passes from inside a body (animal or plant) through the skin.

Allergic contact dermatitis
Allergic contact dermatitis accounts for the remaining 20 per cent of cases. In this condition, the cause of skin inflammation is a hypersensitivity reaction, acting through the body's immune system, to a particular substance or group of related substances.

Allergic contact dermatitis has the following features:

previous exposure to the substance is needed to induce allergy.
the reaction is specific to one chemical or a group of similar chemicals.
all areas of skin that are in contact with the allergy-provoking substance (allergen) develop the rash.
avoidance of the allergen will result in resolution of the rash.

The commonest allergens are:

nickel
fragrances
rubber
some plants
formaldehyde
skin medications (including topical corticosteroids)
hairdressing chemicals.

As with the irritant type, allergic contact dermatitis is more common in atopic individuals.

Location of contact dermatitis and suspicious agents

Location	Suspicious agent
Eyelids	Eye makeup, airborne substances, nail polish
Earlobes or neck	Metal jewellery
Forehead and hairline	Hair dyes
Face	Cosmetics (fragrance or preservatives), airborne substances
Armpits	Deodorants
Hands	Gloves, occupational hazards
Waistband	Elastic or nickel in belt or trouser stud
Feet	Shoes - leather, plastic, glues

What can you do?

Prevention

Use gloves and protective clothing when dealing with potentially irritant substances (even for repeated or prolonged exposure to water).
Thoroughly clean your skin if you come in contact with potential irritants.

Determine the cause

Make a list of substances that come in contact with your skin.
Record the timing of use of each substance and see if it relates to the timing of your dermatitis.
Record the body area exposed to each substance and see if it relates to the site of your dermatitis.

Treatment

Avoid the suspected irritant or allergen. This is sometimes not possible but use of protective clothing, such as gloves, can help. In some cases of occupational exposure, time away from work may be necessary.
Barrier creams (the use of barrier creams is controversial). Their efficacy varies depending on the constituents of the cream and the specific irritant. In general, barrier creams are a poor substitute for gloves.
Suitable moisturisers .
Topical corticosteroids, which suppress the inflammatory reaction so should reduce redness, swelling and pain.

For further information about our Eczema Cream, please follow this link to our Eczema Cream page

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