What questions should I ask during a patient's History of Present Illness (HPI) for a rash?

Essential HPI Questions for Evaluating a Rash

When evaluating a patient with a rash, your first question must determine the date of onset and progression pattern to distinguish acute drug reactions from chronic conditions, followed immediately by identifying whether the first symptom was skin pain, mucosal involvement, or sore throat—critical red flags for life-threatening conditions like Stevens-Johnson syndrome. 1

Timing and Onset

• Document the exact date the rash first appeared and whether it developed suddenly (hours) versus gradually (days to weeks), as acute onset suggests drug reactions or infections while chronic patterns indicate conditions like atopic dermatitis 1
• Ask specifically what the very first symptom was—whether skin pain, sore throat, fever, or the rash itself—since prodromal symptoms preceding the rash strongly suggest serious conditions like SJS/TEN 1
• Determine if the rash is constant, episodic, or seasonal, as this pattern helps differentiate allergic causes (seasonal/episodic) from non-allergic etiologies 1

Symptom Characteristics

• Ask directly: "Is the rash painful or itchy?" Painful rash, particularly on face and chest, raises immediate concern for SJS/TEN, while pruritus without rash suggests systemic causes like cholestasis 1
• Determine the distribution pattern: where did it start and how did it spread? Note whether it involves flexural surfaces (atopic dermatitis), extensor surfaces, or specific body regions 2, 3
• Ask if the patient can make the rash appear or bring it out, as this suggests inducible urticaria 2

Medication and Exposure History

• Document every medication taken in the previous 2 months, including over-the-counter drugs, supplements, and complementary therapies, with exact start dates and any dose escalations 1
• Ask about recent medication switches or brand changes, as these can trigger reactions even with "the same" drug 1
• Inquire about environmental exposures: new detergents, soaps, lotions, occupational chemicals, or specific allergen contact 1
• In endemic areas, specifically ask about tick exposure for rickettsial diseases 1

Red Flag Symptoms Requiring Urgent Assessment

• Ask about mucosal involvement: "Do you have any sores, pain, or redness in your mouth, eyes, nose, or genital area?" as mucosal involvement indicates severe disease requiring immediate evaluation 1
• Inquire about respiratory symptoms: cough, shortness of breath, or wheezing, which can indicate serious systemic involvement or anaphylaxis 1
• Ask about airway symptoms or feeling faint, as cutaneous manifestations with airway obstruction or syncope suggest anaphylaxis 1
• Determine if there is gastrointestinal involvement: diarrhea or abdominal distension 1

Associated Systemic Symptoms

• Document presence of fever and its timing relative to the rash, as fever with rash narrows the differential significantly toward infectious or drug causes 4, 5
• Ask about constitutional symptoms: malaise, weight loss, night sweats, which may suggest lymphoma or other systemic disease 6
• Inquire about joint pain or bone pain, as these suggest autoinflammatory diseases 2

Past Medical and Atopic History

• Ask about personal or family history of atopy: eczema, allergic rhinitis, or asthma, as this context is essential for atopic dermatitis diagnosis 2, 1
• Document previous drug allergies with specific details about the reaction type and timing 1
• Ask about recurrent herpes simplex infections, which can trigger SJS/TEN 1
• In women of childbearing age, determine pregnancy status immediately, as pregnancy-specific rashes require different management 1

Risk Factor Assessment

• Obtain sexual history and IV drug use history as risk factors for HIV and hepatitis, which can present with rash 1
• Ask about recent travel, particularly to areas endemic for specific infectious diseases 4
• Document contact with sick individuals or animals 4
• Verify immunization history in children, as vaccines like MMR or pertussis may have been omitted without good reason 2

Dietary and Lifestyle Factors

• In children with suspected atopic dermatitis, take a detailed dietary history, as parents often experiment with dietary restrictions 2
• Ask about sleep disturbance from itching, which indicates disease severity and impact on quality of life 2
• Determine effect on school, work, or social activities to assess functional impact 2

Critical Pitfalls to Avoid

• Do not dismiss the absence of cutaneous symptoms when anaphylaxis is suspected—absence of skin findings does not rule out anaphylaxis 1
• Do not confuse secondary excoriations from scratching with primary rash; in conditions like cholestasis, the rash is secondary to scratching, not the primary pathology 1
• Do not overlook the complete medication list—patients often forget to mention vitamins, supplements, or "natural" remedies that can cause reactions 7
• Do not assume "same medication" means no reaction—brand switches or formulation changes can trigger new reactions 1