Contact Dermatitis

Question 1

What is contact dermatitis?

Answer 1

An inflammatory skin reaction caused by direct contact with an irritant or allergen.

Question 2

What are the two main types of contact dermatitis?

Answer 2

Irritant Contact Dermatitis (ICD) – Non-immunologic reaction caused by direct damage to the skin by a substance.

Allergic Contact Dermatitis (ACD) – Delayed hypersensitivity (type IV) reaction triggered by contact with an allergen.

Question 3

Name common irritants that cause irritant contact dermatitis.

Answer 3

Soaps, detergents, solvents, acids, alkalis, and prolonged water exposure.

Question 4

Name common allergens that cause allergic contact dermatitis.

Answer 4

Nickel, fragrances, cosmetics, latex, preservatives, and poison ivy (urushiol).

Question 5

What is the primary mechanism of irritant contact dermatitis?

Answer 5

Direct cytotoxic effect on keratinocytes, causing inflammation and disruption of the skin barrier.

Question 6

What is the primary mechanism of allergic contact dermatitis?

Answer 6

Allergen-specific T-cell mediated delayed hypersensitivity (type IV reaction).

Question 7

What are the hallmark symptoms of irritant contact dermatitis?

Answer 7

Burning, stinging, erythema, dryness, scaling, and fissuring, often confined to the site of exposure.

Question 8

How does allergic contact dermatitis typically present?

Answer 8

Pruritic, eczematous lesions (papules, vesicles, or plaques) that may extend beyond the area of direct contact.

Question 9

How is contact dermatitis diagnosed?

Answer 9

Clinical evaluation based on history, exposure patterns, and physical exam findings.

Question 10

What diagnostic test confirms allergic contact dermatitis?

Answer 10

Patch testing, which identifies specific allergens causing the hypersensitivity reaction.

Question 11

What findings differentiate irritant from allergic contact dermatitis?

Answer 11

Irritant Contact Dermatitis: Immediate onset, localized to contact area, no prior sensitization needed.

Allergic Contact Dermatitis: Delayed onset (48–96 hours), may extend beyond the contact site, requires prior sensitization.

Question 12

What is the cornerstone of management for contact dermatitis?

Answer 12

Avoidance of the identified irritant or allergen.

Question 13

What topical treatments are commonly used for contact dermatitis?

Answer 13

Topical corticosteroids to reduce inflammation.

Emollients to restore the skin barrier.

Question 14

When are systemic treatments needed for contact dermatitis?

Answer 14

For severe cases, widespread lesions, or significant pruritus, systemic corticosteroids (e.g., prednisone) or antihistamines may be used.

Question 15

What is the mainstay of topical treatment for contact dermatitis?

Answer 15

Topical corticosteroids to reduce inflammation and pruritus.

Question 16

Name examples of low-potency topical corticosteroids and their indications.

Answer 16

Hydrocortisone 1% or 2.5%—used for mild dermatitis or sensitive areas like the face and intertriginous zones.

Question 17

Name examples of high-potency topical corticosteroids and their indications.

Answer 17

Betamethasone dipropionate, clobetasol propionate—used for severe dermatitis on thicker skin areas like palms or soles.

Question 18

What are potential side effects of prolonged topical corticosteroid use?

Answer 18

Skin atrophy, striae, telangiectasia, and tachyphylaxis (reduced efficacy over time).

Question 19

What non-steroidal topical treatments are available for contact dermatitis?

Answer 19

Topical calcineurin inhibitors: Tacrolimus or pimecrolimus, particularly for sensitive areas like the face or groin.

Barrier creams: Contain zinc oxide or dimethicone to protect against irritants

Question 20

Why might topical calcineurin inhibitors be preferred over steroids?

Answer 20

They avoid steroid-related side effects, especially skin thinning, and are suitable for long-term use.

Question 21

When are systemic corticosteroids indicated in contact dermatitis?

Answer 21

For severe, extensive, or refractory cases involving widespread inflammation.

Question 22

What is a typical systemic corticosteroid regimen for severe cases?

Answer 22

Prednisone 0.5–1 mg/kg/day tapered over 2–3 weeks to prevent rebound dermatitis.

Question 23

What role do emollients play in managing contact dermatitis?

Answer 23

They restore the skin barrier, reduce dryness, and promote healing.

Question 24

Name examples of emollients useful for contact dermatitis.

Answer 24

Petroleum-based ointments, creams with ceramides, or urea-based moisturizers.

Question 25

How is contact dermatitis on the face or eyelids treated?

Answer 25

Use low-potency corticosteroids (e.g., hydrocortisone 1%) or calcineurin inhibitors like tacrolimus.