Allergic or Irritative Contact Dermatitis: Everything You Need to Know

Uncover the signs and treatments for allergic or irritative contact dermatitis. Expert advice to soothe your skin.

Wrist with contact eczema caused by an allergy to a watch strap

Summary

What is Contact Dermatitis?

Two Types of Contact Dermatitis: Allergic or Irritative [1,2]

Contact dermatitis, or contact eczema, manifests in two forms:
 - Allergic contact dermatitis occurs when an individual develops a sensitivity to an allergen after repeated exposure.
 - Irritative contact dermatitis results from direct exposure to an irritating substance that damages the skin, leading to inflammation.

Causes of Contact Dermatitis

Causes of Allergic Contact Dermatitis [1,2]

Among the allergens involved, we find.

 

Woman with contact eczema on her neck and wrist caused by nickel jewellery
Clothing

Nickel (found in costume jewellery, zippers, buttons), dyes and tints (textiles), leather, and adhesives (shoes) are common allergens.

 

Cosmetics

Dyes, hairsprays, nail varnishes, deodorants, lotions, and make-up often contain preservatives, dyes, and fragrances that can cause allergies.

Drawing of mild cleaning products
Drawing showing a tube of dermocorticoids
Skincare Products

Topical creams and gels (antibiotics, anti-inflammatories), antiseptics, and dressings can be allergenic.

 

Occupational Allergens

Latex, epoxy resins, or chemical substances are found in specific professional environments: healthcare, hairdressing, cosmetics, construction, cleaning, agriculture, etc.

Drawing showing the temperature changes that cause eczema
Photo-allergens

These substances can trigger an allergic reaction when exposed to UV rays (sunscreens, perfumes, medications) upon contact with the skin.

Causes of Irritative Contact Dermatitis [1]

Irritants can be physical (repeated friction, abrasions, occlusion) or chemical (detergents, acids).

Factors determining the severity of irritative contact dermatitis symptoms include:
- The amount and concentration of the irritant.
- The duration and frequency of exposure.
- The type of skin (dry, thin, oily, etc.)
- Previous skin conditions (pre-existing atopic dermatitis, injuries, and wounds).
- The environment (extreme temperatures, humidity) can exacerbate symptoms.

What Are the Symptoms of Contact Dermatitis? [1,2]

Symptoms in the Acute Phase

In the acute phase, contact dermatitis is characterized by skin redness and dry patches that cause intense itching (pruritus). On these patches, vesicles filled with clear fluid burst and ooze, especially after scratching. These lesions appear in the direct contact area with the allergen but can sometimes spread. Sensitive areas such as the eyelids, face, or genital organs may also exhibit edema (swelling).

Symptoms of the Subacute and Chronic Phases

The subacute phase is marked by crust formation, scaling, and skin hyperpigmentation. The chronic phase is marked by lichenification: the skin thickens and becomes rough. These symptoms often affect the hands, which are the main location for contact dermatitis.

Differentiating Between Allergic and Irritative Contact Dermatitis

Examining the lesions is not enough to distinguish allergy from irritation, but their symptoms can differ:
- Allergy generally manifests with significant itching. The symptoms of irritative contact dermatitis are mainly sensations of burning, tingling, and pain.
- In case of irritation, symptoms appear quickly. In allergic contact dermatitis, lesions develop 1 to 3 days after exposure to the allergen, in case of repeated exposure. 
- Allergic contact dermatitis heals slower than the irritative form.

 

What Are the Diagnostic Methods for Contact Dermatitis? [1,3]

Interview and Clinical Examination

To diagnose contact dermatitis, doctors will inquire about the patient's symptom history: onset, location, and possible triggering factors. They will also examine the skin thoroughly. Specific questions about the work environment, hobbies, skincare products, and lifestyle habits will help identify potential allergens or irritants.

Allergological Assessment

Patch tests are used to confirm the diagnosis by identifying the responsible allergens. The doctor applies small amounts of potential allergens on the skin, usually on the back. They then examine the skin's allergic reaction to these substances after 48 hours to detect delayed allergic reactions.

How to Distinguish Contact Dermatitis from Atopic Dermatitis? [1,2,3,4]

Distinguishing contact dermatitis from atopic dermatitis can be tricky, as their symptoms overlap. Certain features help differentiate them.

Triggering Factors and Location of Lesions

Contact dermatitis is usually caused by exposure to a specific substance and is limited to the contact area (hands, face, neck). It primarily affects adults.
Atopic dermatitis is a chronic disease that alternates between flare-ups and remissions. It typically affects infants and is often associated with other atopic diseases like asthma and allergic rhinitis. The lesions are generally located on the folds (elbows, knees), cheeks, and neck.

Diagnostic Tests

Allergy tests can identify the allergens of contact dermatitis.
The diagnosis of atopic dermatitis is usually clinical (family history of atopy and associated atopic diseases). Sometimes, allergological tests like specific IgE blood levels are necessary.

How to Treat Contact Dermatitis? [1,3]

Avoidance of Allergens and Irritants

The first step in treating contact dermatitis is avoiding the responsible substances, which may involve various adaptations (skincare products, professional practices, hobbies, and home environment).

Topical Corticosteroids

Topical treatments for dermatitis rely on corticosteroids, to reduce inflammation and itching. Follow the doctor's prescription carefully by applying the ointment or topical cream once a day, only on the lesions, until they disappear entirely, is crucial.

Systemic Treatments

In severe cases, doctors may prescribe oral corticosteroids or retinoids. Antihistamines can also help relieve intense itching.

Preventing Contact Dermatitis [1,5]

Avoid Skin Contact with Allergens and Irritants

Recognizing specific allergens and irritants is fundamental. Preventing contact dermatitis requires skincare changes, such as using hypoallergenic products.

Tips for Skin Protection

Protecting the skin is a fundamental step in preventing contact dermatitis:
- Limit skin contact with moisture.
 - After contact with allergens or irritants, wash hands with lukewarm water and soap-free cleansers, rinse, and dry thoroughly. 
- Regularly use emollients for good skin hydration and to strengthen the skin barrier.
 - Choose hypoallergenic and fragrance-free products.
 - If avoidance is impossible, use protective gloves.

References

1. Litchman G, Nair PA, Atwater AR, et al. Contact Dermatitis. National Library of Medicine. Treasure Island (FL): StatPearls Publishing; 2023 Jan. [Disponible sur :] 
https://www.ncbi.nlm.nih.gov/books/NBK459230/
2. L’Assurance Maladie. Comprendre l’eczéma de contact. Ameli.fr. 2023 Sep. [Disponible sur :] https://www.ameli.fr/assure/sante/themes/eczema-contact/reconnaitre-eczema-contact
3. L’Assurance Maladie. La consultation et le traitement en cas d'eczéma de contact. Ameli.fr. 2023 Oct. [Disponible sur :] https://www.ameli.fr/assure/sante/themes/eczema-contact/consultation-traitement
4. L’Assurance Maladie. Eczéma ou dermatite atopique : causes, symptômes et évolution. Ameli.fr. 2023 Sep. [Disponible sur :] https://www.ameli.fr/assure/sante/themes/eczema-atopique/reconnaitre-eczema-atoiique
5. L’Assurance Maladie. Prévenir les récidives de l’eczéma de contact. Ameli.fr. 2023 Sep. [Disponible sur :] https://www.ameli.fr/assure/sante/themes/eczema-contact/prevention-recidives

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