Dermatologic Drug Reactions and Common Skin Conditions

INTRODUCTION

Drug-induced skin reactions can be irritant or allergic. Allergic drug reactions are classified into exanthematous, urticarial, blistering, and pustular eruptions. Skin disorders discussed include contact dermatitis, diaper dermatitis, and atopic dermatitis.

CLINICAL PRESENTATION

pruritic.

• Drug hypersensitivity syndrome is an exanthematous eruption accompanied by fever, lymphadenopathy, and multiorgan involvement (kidneys, liver, lung, bone marrow, heart, and brain).
• Urticaria and angioedema are simple eruptions that are caused by drugs in 5% to 10% of cases. Other causes are foods (most common) and physical factors such as cold or pressure, infections, and latex exposure. Urticaria may be the first sign of an emerging anaphylactic reaction characterized by hives, extremely pruritic red raised wheals, angioedema, and mucous membrane swelling that typically occurs within minutes to hours. Offending drugs include penicillins and related antibiotics, aspirin, sulfonamides, radiograph contrast media, and opioids.
• Acute generalized exanthematous pustulosis (AGEP) has an acute onset (within days after starting the offending drug), fever, diffuse erythema, and many pustules. Generalized desquamation occurs 2 weeks later. Usual offending drugs include β-lactam antibiotics, macrolides, and calcium channel blockers.
• Sun-induced skin reactions appear similar to a sunburn and present with erythema, papules, edema, and sometimes vesicles. They appear in areas exposed to sunlight (e.g., ears, nose, cheeks, forearms, and hands).
• Diaper dermatitis results in an erythematous rash, and severe cases may have vesicles and oozing erosions. The rash may be infected by Candida species and present with confluent red plaques, papules, and pustules.
• Atopic dermatitis presents differently depending on age. In infancy, an erythematous, patchy, pruritic, papular skin rash may first appear on the cheeks and chin and progress to red, scaling, oozing lesions

DIAGNOSIS

• A comprehensive patient history is important to obtain the following information: ✓ Signs and symptoms (onset, progression, timeframe, lesion location and description, presenting symptoms, and previous occurrence ✓ Urgency (severity, area, and extent of skin involvement; signs of a systemic/ generalized reaction or disease condition) ✓ Medication history ✓ Differential diagnosis
• Lesion assessment includes identifying macules, papules, nodules, blisters, plaques, and lichenification. Some skin conditions cause more than one type of lesion.
• Inspect lesions for color, texture, size, and temperature. Areas that are oozing, erythematous, and warm to the touch may be infected.

TREATMENT

• Goals of Treatment: Relieve bothersome symptoms, remove precipitating factors, prevent recurrences, avoid adverse treatment effects, and improve quality of life.

NONPHARMACOLOGIC THERAPY

If a drug-induced skin reaction is suspected, the most important treatment is discontinuing the suspected drug as quickly as possible and avoiding use of potential cross-sensitizers.

• The next step is to control symptoms (eg, pruritus). Signs or symptoms of a systemic or generalized reaction may require additional supportive therapy. For high fevers, acetaminophen is more appropriate than aspirin or another NSAID, which may exacerbate some skin lesions.
• Most maculopapular reactions disappear within a few days after discontinuing the agent, so symptomatic control of the affected area is the primary intervention. Topical corticosteroids and oral antihistamines can relieve pruritus. In severe cases, a short course of systemic corticosteroids may be warranted.
• Treatment of fixed drug reactions involves removal of the offending agent. Other therapeutic measures include topical corticosteroids, oral antihistamines to relieve itching, and perhaps cool water compresses on the affected area.
• Photosensitivity reactions typically resolve with drug discontinuation. Some patients benefit from topical corticosteroids and oral antihistamines, but these are relatively ineffective. Systemic corticosteroids (eg, oral prednisone 1 mg/kg/day tapered over 3 weeks) are more effective.
• For life-threatening SJS/TEN, supportive measures such as maintenance of adequate blood pressure, fluid and electrolyte balance, broad-spectrum antibiotics and vancomycin for secondary infections, and IV immunoglobulin (IVIG) may be appropriate. Corticosteroid use is controversial; if used, employ relatively high doses initially, followed by rapid tapering as soon as disease progression stops.
• Inform patients about the suspected drug, potential drugs to avoid in the future, and which drugs may be used instead. Give patients with photosensitivity reactions information about preventive measures, such as use of sunscreens and sun avoidance.