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Rhus DermatitisAka: Poison Ivy, Poison Oak, Poison Sumac, Toxicodendron radicans, Rhus toxicodendron

Epidemiology
1. Prevalence of complete Rhus immunity: 10-15%
2. Prevalence Rhus Allergy: Total of 75-85% of U.S. Adults
  1. Consistent Reaction: 50% of U.S. Adults
  2. Reaction to high doses: 25-35% of U.S. Adults
Pathophysiology
1. Allergic Contact Dermatitis to Rhus Group of Plants
  1. Poison Oak (West of the Rocky Mountains)
  2. Poison Ivy (East of the Rocky Mountains)
  3. Poison Sumac (Swampy areas in Florida, Northeast)
2. Hypersensitivity Reaction to urushiol oil
  1. Sensitivity to one plant confers sensitivity to all
  2. Oil leaks out from damaged plant
  3. Oil evaporates from skin within 4 hours
  4. Oil evaporates much more slowly from fomites
    1. Garments
    2. Animal hair (cat, dog)
    3. Ash in smoke from burning leaves
3. Recurrent Eruption is not related to Vesicle leakage
  1. Vesicles have sterile (non Rhus) content
  2. Repeat eruption is related to re-inoculation
  3. See description of slower oil evaporation above
Symptoms
1. Very pruritic rash
Signs
1. Papulovesicular Dermatitis
  1. Linear formation (associated with Rhus oil spread)
Differential Diagnosis
1. Irritant Contact Dermatitis
2. Allergic Contact Dermatitis
3. Viral Exanthem
4. Impetigo (superinfected excoriations)
5. Photocontact Dermatitis
  1. Contrast with Rhus airborne Contact Dermatitis
  2. Does not affect some airborne Rhus areas
    1. Retroauricular folds
    2. Submental folds
    3. Nasolabial folds
Management
1. Symptomatic Treatment
  1. Cool compresses for 15 minutes per time
  2. Colloidal Oatmeal Bath (Aveeno bath)
  3. Calamine lotion applied several times per day
  4. Atarax at bedtime for Pruritus
  5. Burow's Solution
2. Corticosteroid
  1. Topical for Mild to Moderate Localized Involvement
    1. Example: Temovate gel (soothing if refrigerated)
    2. Use Ointment for very dry lesions
  2. Systemic for Severe, Widespread or Periorbital Lesion
    1. Adults
      1. Start: Prednisone 60 mg PO per day divided doses
      2. Taper: Decrease by 10 mg every third day x18 days
    2. Children
      1. Start: Prednisone 0.5 - 2 mg/kg/day to 40 mg/day
      2. Taper by 5 mg every three days over 18 days
  3. Supersensitive patient early in recurrence (<12 hour)
    1. Betamethasone 12 mg IM (short acting) and
    2. Methylprednisolone 40 mg IM (long acting)
3. Antibiotics
  1. Indicated for signs of superinfection
  2. Mild: Topical Antibiotics
  3. Severe: Oral Antibiotics
Course
1. Mild, delayed reaction in 90% patients
  1. Pruritic papulovesicular lesions form over 1-2 days
  2. Resolves over 10 to 14 days
2. Severe reaction in 10% of patients
  1. Onset of debilitating rash over 4 to 8 hours
Prevention
1. Washing off oil immediately may prevent rash
  1. Soap and Water
  2. Solvents poured over area (most effective)
    1. Tecnu Outdoor Skin Cleanser
    2. Gasoline
    3. Acetone
    4. Rubbing Alcohol (isopropyl Alcohol)
  3. Do not dab on solvent (e.g. Alcohol pad, towelettes)
    1. Spreads Rhus oil
  4. Use Solvents only when ready to travel home
    1. Removes lipid protective skin coating
    2. Can predispose to worse second Rhus exposure
2. Clean all contaminated clothing, shoes, and linens
  1. Launder washables
  2. Use Solvents above for non-washables
3. Consider Ivy Block applied to skin prior to exposure
4. Wash pets
5. Identify plants to avoid
6. Wear protective clothing when hiking in weed areas
References

Rhus toxicodendron (C0937645)
Concepts	Organic Chemical (T109) , Pharmacologic Substance (T121)
MSH	D012251
English	Rhus toxicodendron
Sources	MSH, RXNORM Derived from the NIH UMLS (Unified Medical Language System)

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Rhus DermatitisAka: Poison Ivy, Poison Oak, Poison Sumac, Toxicodendron radicans, Rhus toxicodendron

Rhus toxicodendron (C0937645)

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