What is the approach to taking a history (Hx) and performing a physical examination (PE) for a patient presenting with a rash?

History and Physical Examination Template for Rash Evaluation

HISTORY TAKING

Rash Characteristics and Timeline

Document the exact date when the rash first appeared and its progression pattern, as this distinguishes acute drug reactions from chronic conditions and guides drug causality assessment. 1

• Onset and progression: Note whether the rash appeared suddenly or gradually, and how it has evolved over time 2, 1
• Distribution pattern: Document initial location (face, chest, extremities) and direction of spread (centrifugal vs. centripetal) 1, 3
• Morphology changes: Ask if lesions started as one type (e.g., macules) and evolved into another (e.g., petechiae) 2, 4

Associated Symptoms

Prodromal symptoms:

• Fever, malaise, upper respiratory symptoms, sore throat, or skin pain preceding the rash suggest serious conditions like Stevens-Johnson syndrome/toxic epidermal necrolysis 2, 1
• Document the "index date"—when the very first symptom appeared, even before the rash 2, 1

Pain vs. pruritus:

• Painful rash, particularly on face and chest, raises concern for SJS/TEN 1
• Presence or absence of itching helps distinguish conditions with primary rash versus pruritus without rash 1

Red flag symptoms requiring urgent evaluation 2, 1:

• Mucosal involvement (eyes, mouth, nose, genitalia)
• Respiratory symptoms (cough, dyspnea, bronchial hypersecretion, haemoptysis)
• Gastrointestinal symptoms (diarrhea, abdominal distension)
• Airway obstruction or syncope (suggests anaphylaxis)

Medication and Exposure History

Complete medication review 2, 1:

• Document ALL medications taken in the previous 2 months, including over-the-counter products, complementary/alternative therapies, and supplements
• Record exact start dates, dose escalations, and when drugs were stopped
• Note any brand switches or medication errors
• Ask specifically about recent antibiotic use (especially sulfonamides, penicillins)

Environmental and infectious exposures 1, 3:

• Tick exposure, particularly in endemic areas for rickettsial diseases (RMSF peaks April-September)
• Recent travel history, especially to tropical or endemic areas
• Animal contacts and sick contacts
• Outdoor activities in wooded or grassy areas
• Sexual history and IV drug use (risk factors for HIV, hepatitis)

Past Medical and Allergy History

• Previous drug allergies with specific details of reaction type 2, 1
• Personal or family history of atopy (eczema, allergic rhinitis, asthma) 1
• Recurrent herpes simplex virus infections (can trigger SJS/TEN) 2, 1
• Previous or ongoing medical problems, particularly chest infections 2
• Pregnancy status (if applicable, assess location of pruritus) 1

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PHYSICAL EXAMINATION

Vital Signs and General Assessment

Record vital signs, oxygen saturation with pulse oximeter, and baseline body weight for fluid management if severe disease is suspected. 2, 1

• Temperature, heart rate, blood pressure, respiratory rate, oxygen saturation 2, 3
• Mental status (changes with fever suggest encephalitis or sepsis) 1, 3
• Signs of systemic toxicity: tachycardia, confusion, hypotension, altered mental status 4

Systematic Skin Examination

Lesion morphology 2, 5, 6:

• Petechial/purpuric: Non-blanching, suggests meningococcemia, RMSF, vasculitis, or thrombocytopenia
• Maculopapular: Flat or raised lesions, common in viral exanthems and drug reactions
• Vesiculobullous: Fluid-filled lesions, consider SJS/TEN, HSV, VZV, or immunobullous disorders
• Erythematous: Diffuse redness, consider toxic shock syndrome, scarlet fever, or drug reactions

Specific lesion types to identify 2, 1:

• Target lesions (particularly atypical targets)
• Purpuric macules
• Blisters and areas of epidermal detachment
• Nikolsky sign (epidermal detachment with lateral pressure—positive in SJS/TEN)

Distribution and extent 2, 1, 3:

• Palms and soles involvement: Characteristic of RMSF (appears late, day 5-6), secondary syphilis, hand-foot-mouth disease, or bacterial endocarditis
• Face, trunk, extremities: Note which areas are involved and spared
• Sun-exposed vs. covered areas: Helps distinguish phototoxic reactions
• Extensor vs. flexor surfaces: Psoriasis favors extensors; atopic dermatitis favors flexors
• Record extent of erythema and epidermal detachment separately on a body map using Lund and Browder chart 2

Mucosal Examination

Systematic examination of ALL mucosal sites is essential 2, 1:

• Eyes: conjunctivitis, erosions, crusting
• Mouth: mucositis, blisters, erosions, pharyngeal involvement
• Nose: nasal mucosa involvement
• Genitalia: erosions, ulcerations

Additional Physical Findings

• Lymphadenopathy (location, size, tenderness) 5
• Hepatosplenomegaly 5
• Joint involvement (swelling, erythema, tenderness) 3
• Nail changes 5

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CRITICAL PITFALLS TO AVOID

• Do not wait for the classic triad of fever, rash, and tick bite in RMSF—it is present in only a minority of patients at initial presentation 4
• Do not exclude serious disease based on absence of rash—up to 20% of RMSF cases and 50% of early meningococcal cases lack rash 4
• Do not dismiss absence of cutaneous symptoms in suspected anaphylaxis—their absence does not rule out anaphylaxis 1
• Do not confuse excoriations from scratching with primary rash—in conditions like intrahepatic cholestasis of pregnancy, the rash is secondary to scratching 1
• Do not overlook medication history—brand switches or medication errors can trigger reactions 1
• Absence of tick exposure does not exclude RMSF—tick exposure history is present in only 60% of cases 4

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IMMEDIATE ACTIONS FOR LIFE-THREATENING PRESENTATIONS

If petechial/purpuric rash with fever and systemic toxicity 3, 4:

• Start empiric doxycycline immediately if RMSF suspected (even in children <8 years)
• Add ceftriaxone if meningococcemia cannot be excluded
• Do not delay treatment while awaiting laboratory confirmation

If painful rash with mucosal involvement 2, 1:

• Discontinue all potential culprit drugs immediately
• Establish IV access through non-lesional skin if possible
• Consider urgent dermatology consultation for suspected SJS/TEN

If signs of anaphylaxis 1:

• Immediate epinephrine administration
• Airway management as needed