Allergic Contact Dermatitis

what type of reaction is allergic contact dermatitis (ACD)?

type IV, T-cell mediated, delayed reaction

what is urushiol

a plant oil antige only released from the injured plant

how long does it take usuhiol to bind to proteins on exposed skin cells

occurs within 10 mins

what are the 2 steps of poison ivy pathophysiology

1. initial sensitization

2. re-exposure triggers type IV delayed hypersensitivity reaction

how long can a skin rash take to appear with ACD?

can take up to 48 hours

what are the indirect ways that a person can be exposed to poison ivy?

clothing, shoes, pet fur, tools, equipment

how long can urushiol oil stay on inanimate objects for in dry and wet climates

wet- up to 5 years

dry- up to 9 years

what is the direct way that a person can be exposed to poison ivy?

exposure to the plant itself

how can someone get ACD through an airborne pathway

burning the plant can cause the antigen to be carried in smoke

can affect the eyes, lungs, and genitalia this way

what are the 3 characteristcis of poison ivy?

-climbing shrub or vine

-3 leaflets per stem

-central, northeastern US

what are the 3 characteristics of poison oak?

-non-climbing vine or shrub

- 3 leaflets per stem

-west coast, east coast

what are the 3 characteristics of poison sumac?

-shrub or small tree

-7-13 leaflets per stem

-grows in woody, swampy areas

are dead poison ivy plants no longer active?

NO, they're still active

characteristics of ACD

-intense pruritus and erythema (+/- swelling)

-papules

-plaques +/- fluid-filled blisters (vesicles and bullae) that can break open, crust, or scale

how does mild ACD present

linear streaks consistent with location of exposure (secondary to linear contact or brushing against plant or excorations from scratching)

erythematous, possibly edematous

pruritic or mildly painful

+/- small vesicles (+/- weeping lesions)

how does moderate ACD present

more diffuse areas of erythema and edema, severe pruritus and/or pain, vesicles or bullae, papules +/- weeping lesions

how does severe ACD present

extensive (25% of BSA and/or involvement of the face/genitals)

diffuse erythema and edema, along with large blisters (bullae), +/- weeping lesions, +/- papule/plaques, & severe, disabling itching or pain

is the fluid that leaks from the blisters contagious

no, it doesn't have urushiol

what are black spots from poison ivy from?

results from direct contact with a high concentration of oxidized urushiol

how to decontaminate ACD

protect the area- remove & avoid further contact with offending agent

stop the symptoms before they start. wash area with water +/- soap within 10 mins before it has a chance to bind to the skin

symptomatic treatment of inflammation of ACD

-relieve itching & excessive scratching- prevent open lesions & potential secondary infections

-relieve accumulation of debris that arises from vesicle fluids oozing, crusting, and scaling

what are the 10 exclusions for self-treatment (refer to PCP)

-facial or genital involvement

-presence of numerous bullae

-severe itching or vesicle/bullae formation

-signs of infection

-low tolerance of pain or itching

-< 2 yrs old

-dermatitis > 2 wks

-involvement >20% BSA

-impairment of daily activities

-rash appears to clear then worsens

how long is ACD expected to last

14-21 days

3 complications of ACD

-autoinoculation (repeated exposure of antigen)

-excessive scratching may lead to secondary infection (staph or strep)

-inflammatory pigmentation may occur in dark-skinned individuals

what to use to treat mild-moderate dry lesions

OTC hydrocortisone, calamine lotion, colloidal oatmeal baths, baking soda paste, or cool water compress

what to use to treat mild-moderate weeping lesions

add astringent or cool water compress

what to use in general for mild-moderate ACD

can use high potency cortical steroids

how long to use high potency corticosteroids for?

>2 weeks to prevent rebound flare

taper down with lower potency steroids

what to avoid in ACDs

OTC topical products containing antihistamines, anesthetics, or antibiotics

associated with drug-induced dermatitis

what is the preferred treatment of mod-severe ACDs

systemic PO steroids

0.5-1.0 mg/kg/day of PO prednisone, reducing gradually over 14-21 days

what is the alternative option for treating mod-sev ACDs

for localized areas only- high-potency topical steroid creams (prescription strength, class 1-2)

how to taper PO prednisone or methylprednisone

taper over 14-21 days

avoid premade dose packs

prematurely stopping steroid therapy can lead to rebound inflammation

what ingredients can be used to depress skin sensory receptors

-phenol

-menthol

-camphor

how to use colloidal oatmeal (Aveeno)

put oatmeal in a tied sock before dropping into the bath

bathe for 15-20 mins at least BID

what effect do wet compresses have?

they stop oozing, reduce inflammation, and promote healing

dries the weeping lesion and aids in the removal of crusts

what 2 things can you use for a wet compress

cool tap water or aluminum acetate (Burow's solution/Domeboro)

how to use aluminum acetate (Domeboro/Burow's solution)

dilute with water 1:40

use for 15-30 mins

3x/day (soak) or PRN (compress) for 5-7 days when rash is oozing

what are the 3 antipruritics/asringents that can be used to stop oozing, promote healing, and reduce inflammation

-Zinc acetate 2% (Ivy Dry)

-calamine lotion

-sodium bicarbonate (baking soda)

how to use zinc acetate 2% (Ivy Dry)

-apply no more than TID

-avoid use in <6 y/o

how to use calamine lotion

-shake well

-apply q4hrs PRN

-do not apply to open lesions

how to use sodium bicarbonate (baking soda)

-paste or cool compress

-avoid use in <2 years old

preventative measures for ACD

protective clothing: long pants and sleeves

use disposable vinyl gloves (not latex, rubber, cotton)

how to use Ivy Block lotion (5% bentoquatam (quaterinum-18 bentonite))

-shake bottle

-apply 15 mins before exposure

-reapply every 4 hours

-remove with soap and water

-avoid eyes and existing rash

what ages is Ivy Block not recommended in

patients < 6 years old

what is Ivy Block used for

used as a pre-exposure barrier

post-exposure protective measures for ACD

-remove clothing and wash separate from other clothes

-wash skin immediately with any type of soap (within 10 mins preferably)

-if thorough washing not possible, rinse with water

-take a complete shower, avoid tubs

-clean under finernails

-wash equipment/tools/shoes

-cleanse fur of pets after known exposure

how to use Tecnu cleanser

-apply to area ASAP (up to 8 hours post-exposure)

-rub into area for 2+ mins and wipe/rinse with cool water

what ingredients are in Tecnu cleanser

mineral spirits, water, soap, surface-active agent

what are the 3 products used for post poison ivy exposure

tecnu outdoor skin cleanser

Ivy Cleanse

Zanfel