Irritant VS. Allergic Contact Dermatitis: What's the Difference?

With each skin irritation bearing almost the same symptoms, identifying what type of contact dermatitis you got may be difficult. 

Contact dermatitis is a common inflammatory skin condition characterized by inflamed, itchy, and sometimes swollen skin lesions that develop after coming into contact with a specific substance. 

Aside from experiencing constant itch, having contact dermatitis also may heavily impact one's quality of life as it interrupts sleep, makes concentrating difficult, and disturbs a person's performance of duties at work or in school. 

A person who has been exposed to a foreign substance may likely experience the two main types of contact dermatitis. Here's the difference between irritant contact dermatitis (ICD) and allergic contact dermatitis (ACD). 

IRRITANT CONTACT DERMATITIS 

This is the most common type of contact dermatitis, which accounts for 80% of all contact dermatitis cases. ICD typically happens when skin cells are damaged by exposure to irritating substances. 

According to News Medical, this type of reaction shows no characteristic time lapse between exposure and the onset of dermatitis. "The nature and extent of the rash depend on how much of the irritant was present, and the duration of exposure," the health news website explained. 

WHO GETS ICD? 

Since the problem starts through a breach of the skin surface by a harmful substance, ICD will affect anyone who has been sufficiently exposed to irritants. According to DermNetNZ.Org, people who engage in wet works like cleaners, hairdressers, food handlers, and medical professionals experience ICD more often due to the nature of their work. 

WHAT FACTORS CAUSE ICD? 

Several factors may influence the development and severity of the reaction. Wet skin, dry skin, and even extreme climatic conditions are known contributors to make the skin more susceptible to inflammation. DermNetNZ.Org also lists down these factors: 

• Concentration, amount, and properties of the irritant
• Duration and frequency of exposure
• Skin susceptibility such as pre-existing skin damage or atopic tendency
• Mechanical trauma including hand scrubbing
• Environmental factors such as temperature extremes or humidity

WHAT TRIGGERS ICD? 

Since ICD is a skin condition that doesn't involve an allergic reaction by the immune system, the problem often starts through a breach of the skin surface by a substance. The typical triggers of ICD include but are not limited to: 

• Chemicals like acids or alkalis 
• Pesticides 
• Fabric softeners 
• Shampoos
• Solvents
• Detergents
• Soaps
• Bleach 
• Makeup
• Hair dye made with synthetics 
• Nickel-containing jewelry
• Nickel-containing scissors
• Belt buckles
• Zippers 
• Clothes with metal snaps or clasps

ALLERGIC CONTACT DERMATITIS (ACD)

ACD is a form of skin condition caused by a delayed hypersensitivity reaction to a foreign substance, called an allergen, that comes into contact with the skin. The bodies of people with ACD often trigger an immune system response after exposure to the allergen, making their skin red, swollen, flaky, itchy, and painful. 

WHO GETS ACD? 

According to DermNetNZ, ACD is common in the general population and in specific employment groups. 

• More common in women than men, mainly due to nickel and acrylate allergy from nail cosmetics
• Many young children are also allergic to nickel.
• Contact allergy to topical antibiotics is common in patients over the age of 70 years old
• Metalworkers, hairdressers, beauticians, health care workers, cleaners, painters, and florists

WHAT FACTORS CAUSE ACD? 

In the same article, DermNetNZ explained that ACD is a type 4 or delayed hypersensitivity reaction that occurs 48–72 hours after exposure to the allergen. Some things to note:

• ACD occurs predominantly from an allergen on the skin rather than from internal sources or food.
• Only a few people react to the specific allergen, which is harmless to those who are not allergic to it.
• They may have been in contact with the allergen for years without it causing dermatitis.
• Contact with tiny quantities of an allergen can induce dermatitis.
• Patients with impaired barrier function of the skin are more prone to allergic contact dermatitis
• Patients with atopic dermatitis are at a high risk of also developing allergic contact dermatitis.

WHAT TRIGGERS ACD? 

The contact between skin immune cells and specific antigens on the sensitizer "provokes an immune-mediated or allergic reaction." The examples of sensitizing agents or substances that cause ACD include but are not limited to: 

• Adhesives
• Certain topical antibiotics
• Chemicals found in clothing like resin, formaldehyde, and sulfites
• Petroleum-based synthetic fabrics 
• Fragrances used in perfumes, soaps, or cosmetics
• Other cosmetics including nail polish, or hair treatment agents
• Nickel, chromium, or other metals
• Poisonous plants such as poison ivy, or poison sumac
• Rubber or latex gloves or shoes

TAKEAWAY: While there's a thin line between ICD and ACD due to their similarities in symptoms, the causes and treatment for the two main types of contact dermatitis can be different for each person. 

If you have a skin rash that won't go away or hives that won't stop itching, please visit your doctor immediately for emollients or barrier creams. However, if your symptoms aren't improving, it's best to seek an allergy specialist for patch testing and proper treatment in severe cases. 

Experience tells us that we should avoid a certain substance after experiencing a flare-up. That's why there's a need to always be on the lookout for potential triggers that may cause irritation. Good thing, you won't have to learn to avoid them the hard way using our 100% organic cotton clothing. 

At Cottonique, we always believe that the avoidance of all potential irritants and allergens remains the best way to keep your skin from becoming itchy and irritated. For uncompromising prevention of severe allergies and multiple chemical sensitivities, visit our Allergic Contact Dermatitis collection — completely free from harmful allergens, elastics, chemicals, and dyes. 

For more information regarding contact dermatitis, visit this informative resource from National Eczema Association. You may also read our previous blog: Allergy-Free Wardrobe Guide: 4 Factors To Consider When Buying Eczema-Friendly Clothes