- The cutaneous reaction to an external substance
- Primary irritant dermatitis is due to direct injury of the skin. It affects individuals exposed to specific irritants and generally produces discomfort immediately after exposure.
- Allergic contact dermatitis (ACD) affects only individuals previously sensitized to the substance. It represents a delayed hypersensitivity reaction, requiring several hours for the cascade of cellular immunity to be completed to manifest itself.
- System(s) affected: Skin/Exocrine
- Synonym(s): Dermatitis venenata
Occupational contact dermatitis: 20.5/100,000 workers
- Contact dermatitis represents >90% of all occupational skin disorders.
- Predominant sex: Male = Female:
- Variations due to differences in exposure to offending agents as well as normal cutaneous variations between male and female (eccrine and sebaceous gland function and hair distribution)
Increased incidence of irritant dermatitis secondary to skin dryness
Increased incidence of positive patch testing due to better delayed hypersensitivity reactions
Increased frequency of ACD in families with allergies
- Avoid causative agents.
- Use of protective gloves (with cotton lining) may be helpful (1)[A].
Hypersensitivity reaction to a substance generating cellular immunity response
- Rhus-urushiol: Poison ivy, oak, sumac
- Primary contact: Plant (roots/stems/leaves)
- Secondary contact: Clothes/fingernails (not blister fluid)
- Topical medicines:
- Neomycin: Topical antibiotics
- Thimerosal (Merthiolate): Preservative in topical medications
- Anesthetics: Benzocaine
- Parabens: Preservative in topical medications
- Formalin: Cosmetics, shampoos, and nail enamel
- Itchy rash
- Assess for prior exposure to irritating substance
- Papules, vesicles, bullae with surrounding erythema
- Crusting and oozing
- Erythematous base
- Thickening with lichenification
- Where epidermis is thinner (eyelids, genitalia)
- Areas of contact with offending agent (e.g., nail polish)
- Palms and soles more resistant
- Deeper skin folds spared
- Linear arrays of lesions
- Lesions with sharp borders and sharp angles are pathognomonic.
- Well-demarcated area with a papulovesicular rash
Diagnostic Tests & Interpretation
Consider patch tests for suspected allergic trigger (systemic corticosteroids or recent, aggressive use of topical steroids may alter results) (2)[B]
- Intercellular edema
- Based on clinical impression:
- Appearance, periodicity, and localization
- Groups of vesicles:
- Herpes simplex
- Diffuse bullous or vesicular lesions:
- Bullous pemphigoid
- Phototoxic/allergic reaction to systemic allergen
- Seborrheic dermatitis
- Scaly eczematous lesions:
- Atopic dermatitis
- Nummular eczema
- Lichen simplex chronicus
- Stasis dermatitis
- Topical medications:
- Lotion of zinc oxide, talc, menthol 0.25%, phenol 0.5% (Gold Bond, others)
- Corticosteroids for allergic contact dermatitis as well as irritant dermatitis (1)[A]:
- High-potency steroids: Fluocinonide (Lidex) 0.05% ointment t.i.d.–q.i.d.
- Use high-potency steroids only for a short time and then switch to low- or medium-potency steroid cream or ointment.
- Caution regarding face/skin folds: Use lower-potency steroids and avoid prolonged usage. Switch to lower-potency topical steroid once the acute phase is resolved.
- Calamine lotion for symptomatic relief
- Topical antibiotics for secondary infection (bacitracin, erythromycin)
- Hydroxyzine: 25–50 mg p.o. q.i.d., especially useful for itching
- Diphenhydramine: 25–50 mg p.o. q.i.d.
- Prednisone: Taper starting at 60–80 mg/d p.o., over 10–14 days
- Used for moderate-to-severe cases
- May use burst dose of steroids for up to 5 days
- Antibiotics for secondary skin infections:
- Dicloxacillin: 250 mg p.o. q.i.d. for 7–10 days
- Amoxicillin-clavulanate (Augmentin): 500 mg p.o. b.i.d. for 7–10 days
- Erythromycin: 250 mg p.o. q.i.d. in penicillin-allergic patients
- Antihistamines may cause drowsiness.
- Prolonged use of potent topical steroids may cause local skin effects (atrophy, stria, telangiectasia).
- Use tapering dose of oral steroids if using more than 5 days.
Other topical or systemic antibiotics, depending on organisms and sensitivity
Usual cautions with medications
- Removal of offending agent:
- Work modification
- Protective clothing
- Barrier creams, especially high-lipid content moisturizing creams (e.g., Keri lotion, petrolatum, coconut oil) (3)[A]
- Topical soaks with cool tap water, Burow solution (1:40 dilution), saline (1 tsp/pint water), or silver nitrate solution (25.5%)
- Lukewarm water baths
- Aveeno oatmeal baths
- Emollients (white petrolatum, Eucerin)
Issues for Referral
May need referral to a dermatologist or allergist if refractory to conventional treatment
Complementary and Alternative Medicine
The use of complementary and alternative treatment is a supplement and not an alternative to conventional treatment (4).
Rarely will need hospital admission
Stay active, but avoid overheating.
- As necessary for recurrence
- Patch testing for etiology after resolved
No special diet
- Avoidance of irritating substance
- Cleaning of secondary sources (nails, clothes)
- Fallacy of blister fluid spreading disease
- Generalized eruption secondary to autosensitization
- Secondary bacterial infection
1. Saary J, Qureshi R, Palda V, et al. A systematic review of contact dermatitis treatment and prevention. J Am Acad Dermatol. 2005;53:845.
2. Saripalli YV, Achen F, Belsito DV. The detection of clinically relevant contact allergens using a standard screening tray of twenty-three allergens. J Am Acad Dermatol. 2003;49:65–9.
3. Hachem JP, De Paepe K, Vanpée E, et al. Efficacy of topical corticosteroids in nickel-induced contact allergy. Clin Exp Dermatol. 2002;27:47–50.
4. Noiesen E, Munk MD, Larsen K, et al. Use of complementary and alternative treatment for allergic contact dermatitis. Br J Dermatol. 2007.
See Also (Topic, Algorithm, Electronic Media Element)
Algorithm: Rash, Focal
- 692.0 Contact dermatitis and other eczema due to detergents
- 692.3 Contact dermatitis and other eczema due to drugs and medicines in contact with skin
- 692.4 Contact dermatitis and other eczema due to other chemical products
- 692.9 Contact dermatitis and other eczema, unspecified cause
- 692.6 Contact dermatitis and other eczema due to plants (except food)
- 692.81 Dermatitis due to cosmetics
- 692.83 Dermatitis due to metals
- 692.89 Contact dermatitis and other eczema due to other specified agents
- 40275004 contact dermatitis (disorder)
- 30451004 contact dermatitis due to detergents (disorder)
- 86062001 contact dermatitis due to drugs AND/OR medicine (disorder)
- 3226008 contact dermatitis due to non-medicinal chemical (disorder)
- 200821000 contact dermatitis due to plants (disorder)
- 78755001 contact dermatitis due to cosmetics (disorder)
- 267796002 contact dermatitis due to metal (disorder)
- 6888008 contact dermatitis due to dye (disorder)
- Anyone exposed to irritants or allergic substances is predisposed to contact dermatitis, especially in occupations that have high exposure to chemicals.
- The most common allergens causing contact dermatitis are plants of theToxicodendron genus (poison ivy, poison oak, poison sumac).
- The usual treatment for contact dermatitis is avoidance of the allergen or irritating substance and temporary use of topical steroids.
- A contact dermatitis rash presents in a nondermatomal geographic fashion, due to the skin being in contact with an external source.