What could be causing sunburn-like symptoms without actual sun exposure in a patient with unknown medical history and demographics?

Sunburn-Like Symptoms Without Sun Exposure

The most likely causes are drug-induced photosensitivity or photodermatoses, requiring immediate medication review and discontinuation of photosensitizing agents. 1, 2, 3

Immediate Assessment and Action

Medication Review (First Priority)

Discontinue all potentially photosensitizing medications immediately if drug-induced photosensitivity is suspected. 3 The most common culprits include:

• Cardiovascular medications: ACE inhibitors (ramipril, enalapril, quinapril), ARBs (candesartan, irbesartan, losartan, olmesartan, telmisartan, valsartan), thiazide diuretics (hydrochlorothiazide), and calcium channel blockers (amlodipine, diltiazem) 1
• Anti-arrhythmic drugs: Amiodarone (causes photosensitivity in >50% of patients with burning and tingling sensation in sun-exposed skin) and dronedarone 1
• Antidepressants: Citalopram, clomipramine, escitalopram, fluoxetine, fluvoxamine, imipramine, paroxetine, sertraline, St. John's wort, and venlafaxine 1
• Antimicrobials: Fluoroquinolones, tetracyclines, sulfonamides, and anti-fungals 1
• Beta-blockers: Tilisolol 1

The typical presentation is a burning and tingling sensation in sun-exposed skin with associated erythema, even without actual sun exposure. 1

Clinical History Requirements

Obtain specific details about:

• Timing and pattern: When symptoms began relative to medication initiation, UV exposure (including through windows), or phototherapy 2
• Distribution: Whether symptoms affect sun-exposed areas (face, neck, forearms, hands) or generalized 2
• Associated symptoms: Fever, malaise, nausea, systemic symptoms 4, 5
• Recent phototherapy: PUVA or narrowband UVB treatments within the past 24-96 hours 1, 3

Differential Diagnosis

Drug-Induced Photosensitivity

This is the most common cause in patients on cardiovascular or psychiatric medications. 1 Thiazide diuretics trigger exaggerated sunburn reactions, dermatitis, and lichenoid eruptions. 1 Amiodarone can cause distinctive blue-grey pigmentation on sun-exposed sites in 1-2% of patients after long-term exposure. 1

Photodermatoses

• Solar urticaria: Rapid onset of urticaria after sun exposure 2
• Chronic actinic dermatitis: Persistent eczematous reaction in sun-exposed areas 2
• Polymorphous light eruption: Delayed reaction to UV exposure 2

Solar Burn Reactivation

A rare idiosyncratic drug reaction where previous sunburn areas become severely inflamed after drug administration (particularly methotrexate) without further sun exposure. 4 This can progress to second-degree burns and requires immediate drug discontinuation. 4

Sun Pain/Solar Dysesthesia

Intense pain, burning, dysesthesia, and hyperalgesia after brief sun exposure without visible skin lesions. 5 Patients may also develop systemic symptoms including mild fever, fatigue, and fainting. 5 This condition is strongly associated with fibromyalgia, major depressive disorder, bipolar syndrome, or conversion disorder. 5

Diagnostic Workup

Initial Laboratory Studies

• Complete blood count with differential 2
• Comprehensive metabolic panel (including renal function if on methotrexate or other nephrotoxic drugs) 2, 4
• Drug levels if applicable (e.g., methotrexate level if recently administered) 4

Specialized Testing (Dermatology Referral)

• Phototesting: Minimal erythema dose determination for UVA and UVB 2
• Minimum urticarial dose testing: For suspected solar urticaria 2
• Genetic testing: If xeroderma pigmentosum or inherited photosensitivity disorders suspected 2

Neuropsychiatric Evaluation

For patients with severe pain and symptoms without visible skin lesions or laboratory evidence of known photodermatoses, neuropsychiatric evaluation should be obtained. 5 Five out of ten patients in one series were diagnosed with fibromyalgia, and psychopharmacological treatment with antidepressants improved both neuropsychiatric symptoms and sun sensitivity. 5

Management Algorithm

Step 1: Immediate Interventions

• Stop all photosensitizing medications 3
• Avoid all sun exposure for at least 24 hours, including indirect exposure through windows 3
• Apply broad-spectrum sunscreen (SPF ≥30) to all exposed skin areas 2, 3
• Use protective clothing: Long-sleeved shirts, long pants, broad-brimmed hats 2, 3

Step 2: Symptomatic Treatment

For mild to moderate symptoms:

• NSAIDs: Ibuprofen 800mg or acetaminophen for pain control 6
• Topical emollients: Petrolatum-based products, honey, or aloe vera 6
• Cool compresses: Clean running water for 5-20 minutes if acute burning sensation 6

Step 3: Monitoring and Follow-Up

• Monthly skin examinations during active phototherapy or if photosensitizing medications cannot be discontinued 3
• Annual full-body skin examinations by dermatologist for all patients with chronic photosensitivity 2, 3
• Patient self-examination for new or changing lesions 3

Critical Pitfalls to Avoid

Do Not Delay Medication Discontinuation

If drug-induced photosensitivity is suspected, waiting to confirm the diagnosis before stopping the offending agent can lead to severe reactions including second-degree burns. 4 The risk-benefit analysis favors immediate discontinuation in most cases.

Do Not Ignore Systemic Symptoms

Fever, malaise, nausea, and elevated creatinine may indicate methotrexate toxicity with solar burn reactivation, requiring hospitalization and aggressive supportive care. 4

Do Not Dismiss Pain Without Visible Lesions

Patients with intense pain but no visible skin changes may have solar dysesthesia, which requires neuropsychiatric evaluation rather than dermatologic treatment alone. 5 These patients often have underlying fibromyalgia or mood disorders that respond to antidepressants. 5

Do Not Underestimate PUVA-Related Reactions

PUVA erythema peaks at 96 hours or later, not immediately after treatment. 1, 3 Patients must avoid all sun exposure for 24 hours after PUVA and wear UVA-blocking protective eyewear. 3

Special Considerations

Phototherapy Patients

If symptoms occur during or after narrowband UVB or PUVA treatment:

• Report all redness or discomfort to phototherapy nurse before each subsequent treatment 1
• Shield recent skin cancer sites or surgical scars completely 1, 3
• No sunscreen application on treatment days before phototherapy, as this creates areas of differential tolerance 1
• Treatment intervals: Maintain at least 48 hours between narrowband UVB treatments and 2-3 days between PUVA treatments 1, 3

Window and Indoor UV Exposure

UV radiation can penetrate windows, particularly UVA. 1 Patients on photosensitizing medications should use UV-blocking window films in vehicles and consider indoor sun protection measures. 3