Allergic Contact Dermatitis (ACD) – An Informative Guide to Causes, Symptoms, Diagnosis and Treatment

Pietro Ponzoni
May 5
3 min read

Occupational Contact Dermatitis

Occupational contact dermatitis accounts for the vast majority of work-related skin diseases (almost 90%). It occurs due to direct contact with external agents present in the workplace environment. Understanding these conditions is essential for prevention, diagnosis, and management within the field of occupational medicine.

There are two main types of occupational contact dermatitis, which differ in their mechanism and triggers:

Allergic Contact Dermatitis (ACD)
Irritant Contact Dermatitis (ICD)

Although the symptoms may be similar, distinguishing between ACD and ICD is crucial, as their diagnostic strategies and treatments differ. Properly addressing these professional skin conditions is vital to protect workers' skin health and ensure a safe work environment.

Allergic Contact Dermatitis (ACD)

This article focuses on Allergic Contact Dermatitis (ACD), a skin reaction in which the immune system responds to substances considered “foreign” (allergens) present in the workplace. Let’s explore how it develops, its causes, symptoms, how it’s diagnosed, and possible treatments.

📌 Stay tuned for the next article on Irritant Contact Dermatitis (ICD): we’ll explore its specific characteristics and the key differences from ACD, providing a guide to managing this common skin issue as well.

How Allergic Contact Dermatitis Develops

When the skin comes into contact with an allergenic substance, in some individuals the immune system recognizes it as harmful and reacts. This process occurs in two phases:

Sensitization Phase: In this initial phase (which may last days or even years), the body "learns" to recognize the allergen. Skin cells called Langerhans cells capture the substance and transport it to the lymph nodes, where it is presented to the immune system.
Elicitation Phase: Upon subsequent exposure to the same substance, the immune system responds with an inflammatory reaction. The main symptoms typically appear 24–48 hours after contact.

Causes and Common Allergens

ACD can be triggered by even very small amounts of an allergen, once the person is sensitized. The main culprits include:

Metals: Nickel is the most common, but chromium, cobalt, and mercury (found in jewelry, buttons, and other objects) can also cause reactions.
Plants: Poison ivy, poison oak, and poison sumac are frequent triggers, as well as plants like primrose and mango peel.
Perfumes and Fragrances: Common in cosmetics, detergents, and personal care products.
Preservatives and Topical Medications: Found in shampoos, creams, ointments, and skin-applied medications.
Rubber, Latex, and Dyes: Used in gloves, medical devices, and even fabrics or textiles.

Symptoms and Clinical Signs

People affected by ACD usually experience:

Intense Itching: Often the most bothersome symptom, possibly accompanied by pain in more extensive lesions.
Skin Lesions: Initially redness, followed by blisters (small fluid-filled bubbles), papules, swelling, and crusts. If the condition becomes chronic, the skin may thicken, crack, or flake.
Lesion Distribution: Typically occurs in areas that come into direct contact with the allergen (e.g., hands, face, neck, or other exposed areas).

Diagnosis and Occupational Link

Diagnosis is based on:

Medical History: A detailed interview about the job and potential allergen exposures.
Physical Examination: Assessment of lesions and affected areas.
Patch Test: Small amounts of allergens are applied to the skin for 48 hours, followed by readings at 48, 72, and 96 hours. A delayed reaction helps confirm the diagnosis of ACD.

Treatment and Prevention

Proper ACD management involves:

Avoiding the Allergen: The first and most important measure is identifying and minimizing exposure.
Pharmacological Treatment:
- Corticosteroids: Topical or, in severe cases, oral, to reduce inflammation.
- Antihistamines: To relieve itching.
- Emollients: Moisturizing creams to help restore the skin barrier.
Preventive Measures: Use of gloves and other protective devices, along with hypoallergenic product choices, are key strategies.

Conclusion

Timely identification of the allergen and adoption of targeted measures are essential to improve the quality of life for workers affected by ACD.To learn more about another common occupational skin issue, stay tuned for our next article on Irritant Contact Dermatitis (ICD), which will cover its specific characteristics and how it differs from ACD.

👉 Want to explore more topics on workplace health and safety?Browse our blog for more insights and the best prevention and protection strategies for workers.📎 Click here → https://www.pietroponzoni.com/blog

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