Contact Dermatitis

What prompted this article is an episode of distressing skin inflammation by one of the authors of this blog. For some background information, this writer is a creature of repetitive habits without a shadow of a doubt. After a recent change in one of the facial topical products, the skin over their face started to become red, inflamed, painful, and very itchy after just three days of use.

The skin is the largest organ in our body. While building a good skin barrier layer takes months to years, acute contact dermatitis can lead to an evident and sudden skin deterioration due to an acute skin barrier breakdown. This can happen to anybody.

In this article, we delve into the types of contact dermatitis, causes of the condition, ways to minimise developing contact dermatitis, and tips to rescue the affected skin.

What is contact dermatitis?

As the name suggests, contact dermatitis is defined as a skin inflammatory condition due to direct contact with the application of substances onto the skin’s surface. Contact dermatitis can occur on any part of the body, though the hands, face, and feet are frequently affected.

There are two types of contact dermatitis: irritant contact dermatitis and allergic contact dermatitis.

What are the symptoms of contact dermatitis?

Patients with contact dermatitis tend to present with:

• Redness
• Itch
• Pain
• Burning sensation
• Blisters and ooziness of the affected skin (in severe cases)

What causes contact dermatitis?

The skin rash response during contact dermatitis is a negative inflammatory response from one or more external agents in touch or contact with the skin. This leads to a vicious cycle of weakening the skin barrier, inflammation over the skin, and further impairing the skin's protective layer.

In irritant contact dermatitis, the external agents present as irritants that corrode the normal skin barrier, leading to a skin inflammatory response. The most common irritants include water, strong chemicals (acid or alkalis), detergents, solvents, and abrasives (repeated friction). Strong irritants cause immediate breakdown of the skin barrier, leading to a skin reaction within hours after exposure. Generally, after repetitive and cumulative exposure to irritants over months and years, individuals may notice a more subtle skin reaction over time.

In allergic contact dermatitis, an interesting delayed allergic response takes place. This is known as a type 4 hypersensitivity allergic reaction. To begin with, patients with allergic contact dermatitis tend to have eczema with a weaker overall skin barrier. The introduction of external substances to the skin allows even easier access due to a weakened skin barrier. The substance is recognised by T-cells (immune cells) in the body, and upon repeated exposure to an external substance, the body’s immune system is reinforced and re-challenged with the external substances, leading to the development of an allergic skin response.

In allergic contact dermatitis, auto-sensitisation may even occur due to the awakening of the immune system, leading to a generalised spread of the rash. For example, a person may start with a facial rash due to direct contact with an allergen substance on the face; there may be a further spread of rash throughout the body and lower limbs due to auto-sensitisation.

Although irritant and allergic contact dermatitis is often discussed and explained separately, clinical practice commonly sees both causes occur simultaneously.

In irritant and allergic contact dermatitis, the skin barrier is compromised as the skin integrity is no longer at its best. This can be due to irritated skin or an allergic response. Subsequently, the skin will continue to deteriorate by a physical manifestation of increased damage.

What are the common irritants and allergens that cause contact dermatitis?

Common irritants that cause contact dermatitis include:

• Water
• Chemicals
• Oils
• Detergents
• Soaps
• Humidity
• Temperature changes
• Dust
• Abrasive frictions
• Solvents

Common allergens that cause contact dermatitis include:

• Nickel (such as earrings, jewellery, watches, and belts)
• Rubber
• Fragrances
• Cobalt
• Colophonium (glue)
• Paraphenylenediamine (hair dye)
• Preservatives
• Make-up products

If you are unsure of which of these are causing the above symptoms, a skin prick allergy test is a simple and accurate way to detect allergies. Allergy treatment will follow depending on the results.

What are the differences between irritant contact dermatitis and allergic contact dermatitis?

There are few tell-tail signs to differentiate the presentation between irritation and allergic contact dermatitis, though often the presentation may not be as clear-cut and may co-exist simultaneously.

	Irritant contact dermatitis	Allergic contact dermatitis
Common sites	Hands	Exposed areas of the skin
Borders of skin rash	Strictly confined to the exposure site	Demarcated borders, though, may spread to the peripherals and become generalised
Clinical symptoms (Acute)	Intense stinging, pain, then eventually itching	Itching, which can lead to pain
Clinical symptoms (Chronic)	Itching and pain	Itching and pain
Appearance (Acute)	Redness, blisters, broken skin, erosions crust, and scaling	Redness bumps, broken skin, crust, and scaling
Appearance (Chronic)	Bumps, crust, scales, fissures	Bumps, patches, scaling, crust
Timeline (Acute)	Rapid, within hours after exposure	12 to 72 hours after exposure

How is contact dermatitis managed?

The key to managing contact dermatitis is to eliminate and stop the offending substance(s) that plays a role in contact dermatitis.

In the real world, sometimes, complete elimination of the offending substance(s) may not be feasible due to the nature of certain occupations, or common irritants such as water or dust may not be wholly avoided. However, understanding the possible culprit(s) is important, as unnecessary exposure to irritants or allergens can be minimised. 

For example, in the case of water irritants, one should avoid repetitive unnecessary washing and use protective hand gloves when available and possible. If your workplace allows, consider protective gear or even a change of job roles to avoid exposure to offending substances.

Patients with contact dermatitis should be encouraged to repeatedly use moisturiser and barrier cream to maintain the skin barrier integrity. Avoid moisturisers with plant-based proteins, chemicals, or even fragrances. In active inflammation cases, topical steroids or even oral steroids may be required to manage the condition.

It is a knee-jerk reflex when the skin condition deteriorates, and we wish to troubleshoot it with various medications and creams on the affected area(s). Often, this may lead to further introduction of more irritants or allergens that potentially worsen inflamed skin. It is important to take a step back and remind ourselves that in contact dermatitis, less is more. Stop triggering substance(s) and avoid further aggravation!

Can we manage contact dermatitis?

The outcome of contact dermatitis depends on whether the triggering external substance(s) can be avoided. If this is achievable, one can prevent further episodes of dermatitis. This may be challenging, as there may be more than one offending factor involved in contact dermatitis, and complete avoidance of the offending factors may be impractical.

Speak to your doctor if you are dealing with contact dermatitis. Your doctor can guide you further in evaluating the root of your condition and ways to manage the symptoms.

References

1. Richard P. Usatine MD and Marcela Riojas MD. Diagnosis and Management of Contact Dermatitis. Am Fam Physician. 2010;82(3):249-255
2. Johansen JD, Frosch PJ, Lepoittevin JP (eds). Contact Dermatitis 5th Ed. 2010; Berlin. Springer. A comprehensive detailed up-to-date reference book.
3. Britton JE, Wilkinson SM, English JE, et al. The British standard series of contact dermatitis allergens. Br J Dermatol 2003; 148: 259-64.
4. Johnston GA, Exton LS, Mohd Mustapa MF, Slack JA, Coulson IH, English JS, Bourke JF. British association of Dermatologists Guidelines for the management of Contact Dermatitis 2017. BJD 2017 Feb 176 (2) 317-329.