Mountain Cedar Rash: Management of Allergic Reactions
Mountain cedar (Juniperus ashei) does not cause true contact dermatitis or "rash" on the skin—it causes respiratory allergic rhinoconjunctivitis through pollen inhalation, not dermal contact. The term "mountain cedar rash" is a misnomer; patients experiencing skin symptoms likely have either unrelated contact dermatitis or systemic allergic manifestations.
Understanding Mountain Cedar Allergy
Mountain cedar is a respiratory allergen, not a contact allergen:
- Mountain cedar pollen contains the major allergen Jun a 1, a glycoprotein that triggers IgE-mediated respiratory allergic disease when inhaled 1
- Research specifically demonstrates that mountain cedar wood, leaves, and smoke from burning trees contain no allergens capable of causing allergic reactions through skin contact 2
- Mountain cedar is recognized as one of the 35 key aeroallergens of North America, classified specifically as a tree pollen allergen 3
- The pollen season in south central Texas runs from late December through February with dependable and intense pollen density 2, 4
If True Contact Dermatitis is Present
When a patient presents with actual dermatitis during mountain cedar season, investigate other causes:
Diagnostic Approach
- Determine if the dermatitis resolves with avoidance of suspected contactants 5
- Clinical features alone are unreliable in distinguishing allergic from irritant contact dermatitis, particularly with hand and facial eczema 3
- Patch testing should be performed when: 6, 7
- The causative allergen is unknown
- The dermatitis has unusual distribution
- The condition persists despite treatment
- There is later onset or significant worsening
Treatment of Confirmed Contact Dermatitis
For localized acute allergic contact dermatitis:
- Apply mid- to high-potency topical corticosteroids such as triamcinolone 0.1% to affected areas two to three times daily 8, 5
- Escalate to very high-potency agents like clobetasol 0.05% for persistent dermatitis 6, 5
For extensive contact dermatitis (>20% body surface area):
- Systemic corticosteroid therapy is required, providing relief within 12-24 hours 5
- For severe cases, oral prednisone should be tapered over 2-3 weeks to prevent rebound dermatitis 5
Complete avoidance of the identified allergen is the most critical step and offers the best chance for resolution 6, 7
Management of Mountain Cedar Respiratory Allergy
Since mountain cedar causes respiratory symptoms, not dermatitis, appropriate management includes:
Pharmacologic Treatment
- Second-generation antihistamines like fexofenadine are first-line for seasonal allergic rhinitis 9
- Fexofenadine 60 mg twice daily or 180 mg once daily for adults 9
- For children 6-11 years: 30 mg twice daily 9
Allergen Immunotherapy
- Mountain cedar is suitable for allergen immunotherapy as one of the key North American allergens 3
- Pollen from cypress family members (juniper, cedar, cypress) strongly cross-react, so one member is adequate for skin testing and immunotherapy 3
Common Pitfalls to Avoid
Do not assume skin symptoms during mountain cedar season are caused by the pollen:
- Mountain cedar allergens are not present in wood, leaves, or smoke from burning trees 2
- Berry allergen content is too small to cause clinical reactions 2
- Smoke from burning mountain cedar may be irritating but contains no allergens 2
If treating presumed contact dermatitis, avoid:
- Using very hot water for washing, which exacerbates irritant contact dermatitis 10, 7
- Rapid discontinuation of systemic steroids in severe cases, which causes rebound dermatitis 5
- Continuing exposure to identified allergens, which prevents healing 7
The prognosis for allergic contact dermatitis is worse than irritant dermatitis unless the allergen is identified and completely avoided 3, 6