Chemical contact dermatitis is an inflammatory reaction of the skin mucosa due to contact with chemical substances. It is characterized clinically by the occurrence of sharp-edged damage at the site of contact, ranging from edematous erythema in mild cases to papules, blisters and even blisters in more severe cases, and epidermal loosening and even necrosis in more severe cases.
I. Clinical symptoms
Dermatitis performance is generally non-specific, due to the nature of exposure, concentration, contact method and individual reaction, the occurrence of dermatitis form, scope and severity of different, mild local erythema, light red or bright red, slightly edematous, or pinpoint size papules dense, in severe cases, erythema swelling obvious, on the basis of which there are most papules, blisters, vesicles, ooze and crust.
Most of the conscious symptoms are itching, burning sensation or swelling pain, and a few severe cases may have systemic reactions, such as fever, chills, headache and nausea.
Diagnostic points
1. History of exposure to irritants or allergens.
2. The rash often occurs at the site of contact with the irritant.
3, the rash form often varies depending on the nature of the contact, such as allergens are often clear-edged, erythema, papules, blisters, can also occur self allergy; such as irritants are often red, swollen, blisters or blisters, erosion and even necrosis can occur.
4.Itching and burning sensation, heavy pain, fever and other systemic symptoms.
5, the course of the disease is self-limiting, certain allergens caused by the rash can be removed after the cause of l to 2 weeks can subside.
6. Positive skin patch test for allergens.
Treatment
1. Timely removal of irritants that remain or may remain on the skin. Emphasis should be placed on rinsing with plenty of running water for 20-30 minutes immediately after contact with the irritant, and the rinsing time should be extended for alkaline substances as appropriate; do not leave out the scalp and skin folds when rinsing.
2. Temporarily avoid contact with pathogenic substances and other factors that may aggravate the disease.
3.Topical treatment: Select appropriate dosage of topical medication according to the shape and scope of lesions.
(1) Acute phase: It is appropriate to use 3% boric acid solution or saline for continuous or intermittent wet dressing as appropriate for damage showing large amount of exudate. Erythema without solution, edematous erythema, papules, water scarring damage can be applied externally with furnace glycolate lotion, shock lotion, camphor puff powder, several times a day, or topical corticosteroid cream, such as 0,05% dexamethasone ointment, 0,1% chrysosone-A acetate ointment, compounded connarol ointment containing 0,1% chrysosone-A acetate, 0,025% fluorine easy acetate ointment, 0,1% dexamethasone acetate ointment, 0,0 025% percocet ointment, 0.05% clobetasol propionate, etc., 2~3 times a day.
(2) subacute damage: with a small amount of exudate, mild erosion of subacute damage is suitable for external use of paste, such as zinc oxide paste, containing 0.5% neomycin 3 “5% furosemide paste, etc., 2 times a day.
(3) chronic damage: infiltration thickening or mossy lesions can be topical ointment, anhydride or spiritus composed of the above drugs, which can still be added to the urea or for local wrapping to improve the effectiveness. In the acute stage, do not use irritating anhydride, spiritus and impermeable ointment to avoid aggravating the disease.
4.Systemic treatment
(1) antihistamine drugs: H1-receptor antagonists (H1-antihistamines) are mostly used for treatment. The drugs can antagonize the histamine-induced capillary dilation and increased permeability caused by erythema, wind mass, but more with different degrees of central inhibitory effect. At present, the commonly used H1 receptor antagonists are paracetamol, ketotifen, cyproheptadine, dechlorothiazide, ketamine, fexofenadine and reserpine, etc., of which reserpine has a strong and long-lasting effect, and no central inhibitory effect. Generally, 1~2 kinds of treatment can be used as appropriate. Usage: Xithromax once a day, one tablet each time; ketotifen twice a day, one tablet each time; the rest are three times a day, one tablet each time.
(2) 10% calcium gluconate 10m1, 10% sodium thiosulfate 10m1 or vitamin C 0,5″1g, intravenous injection, once a day.
(3) Glucocorticosteroid: for those with extensive lesions or recurrent episodes showing high allergy. Glucocorticoids inhibit dermatitis mainly through anti-inflammatory and anti-allergic effects. The initial dose is prednisone 40~60mg/day orally, or dexamethasone 5~10mg/day intravenously, to be discontinued after the symptoms are controlled and the dose is reduced as appropriate.