What is the management plan for an HIV patient with an erythematous flat rash on the chest and extremities, who has taken naproxen and sumatriptan, and is experiencing diarrhea?

Management of Erythematous Flat Rash in HIV Patient on Antiretrovirals with Recent NSAID and Triptan Use

Immediately discontinue naproxen as the most likely culprit, assess rash severity to exclude life-threatening conditions, and provide supportive care while closely monitoring for progression.

Immediate Assessment and Critical Exclusions

Assess for severe cutaneous adverse reactions (SCAR) that require immediate hospitalization: 1

• Check for mucosal involvement (oral, ocular, genital lesions), blistering, skin exfoliation, or detachment suggesting Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) 2, 1
• Measure fever - temperature >39°C indicates severe hypersensitivity requiring immediate drug cessation 2
• Calculate body surface area (BSA) involvement to grade severity: <10% (Grade 1), 10-30% (Grade 2), >30% (Grade 3), or life-threatening with mucosal involvement (Grade 4) 1
• Evaluate for DRESS syndrome - look for lymphadenopathy, hepatitis (check transaminases >5x upper limit normal), or other organ involvement, though this typically appears weeks after drug initiation 2, 1

Most Likely Diagnosis: Naproxen-Induced Cutaneous Reaction

Naproxen is the primary suspect given the temporal relationship and well-documented association with fixed drug eruptions and erythematous rashes in multiple case reports 3, 4, 5:

• Naproxen can cause chronic rashes lasting years that resolve promptly upon discontinuation 3
• Fixed drug eruptions from naproxen present as erythematous macules that can become pigmented 4, 5
• The flat erythematous presentation on chest and extremities is consistent with naproxen hypersensitivity 3, 5

Sumatriptan is less likely to cause rash but has been associated with ischemic colitis presenting with diarrhea, which may explain the gastrointestinal symptoms 6

HIV antiretrovirals remain a consideration but are less likely if the patient has been stable on medications without recent changes 2, 7:

• Antiretroviral hypersensitivity typically occurs within the first weeks of therapy 2, 1
• NNRTIs (nevirapine, efavirenz) and abacavir are the most common culprits, not mentioned in this case 2, 1
• Emtricitabine (in Truvada) causes mild rash in 17% but usually presents as asymptomatic maculae on palms/soles 7

Immediate Management Algorithm

For Grade 1 Rash (<10% BSA, no systemic symptoms):

• Discontinue naproxen immediately and permanently - do not rechallenge as reactions worsen and occur sooner with re-exposure 2, 7
• Discontinue sumatriptan temporarily given the diarrhea, which may represent ischemic colitis from triptan-induced vasoconstriction 6
• Continue HIV antiretrovirals if patient has been stable on them without recent changes, as approximately 50% of mild antiretroviral rashes resolve spontaneously even with continuation 2
• Apply topical emollients and mild-to-moderate potency topical corticosteroids to affected areas 1
• Prescribe oral antihistamines (non-sedating preferred) for symptomatic relief of pruritus 7, 1

For Grade 2 Rash (10-30% BSA):

• Hold all suspected medications immediately including naproxen, sumatriptan, and consider holding antiretrovirals 1
• Apply medium-to-high potency topical corticosteroids 1
• Use oral antihistamines for symptom control 1
• Monitor weekly until improvement to Grade 1 8

For Grade 3 or 4 Rash:

• Hospitalize immediately 1
• Permanently discontinue all suspected causative agents 1
• Administer high-potency topical corticosteroids or IV methylprednisolone for Grade 4 1

Laboratory Workup

Obtain baseline studies to assess severity and rule out systemic involvement: 1, 8

• Complete blood count (check for eosinophilia suggesting DRESS or drug hypersensitivity) 1, 8
• Comprehensive metabolic panel (evaluate liver function - ALT >5x upper limit normal indicates severe hypersensitivity requiring immediate drug cessation) 2, 1
• Consider stool studies if diarrhea persists after stopping sumatriptan to exclude infectious causes 6

Expected Timeline for Resolution

Most mild to moderate drug-induced rashes improve within days of stopping the offending medication, but new lesions may continue appearing for 2-3 weeks 7:

• Naproxen-induced rashes typically resolve promptly after discontinuation 3
• Antiretroviral rashes may worsen temporarily after cessation, particularly with longer half-life drugs 2
• Monitor closely during the first 2-3 weeks as reactions can progress despite drug withdrawal 7

Critical Pitfalls to Avoid

• Never use prophylactic corticosteroids or antihistamines when restarting medications known to cause rash, as this increases rash incidence rather than preventing it 2, 1
• Never rechallenge with naproxen if confirmed as the causative agent - hypersensitivity reactions are more severe and potentially fatal with re-exposure 2, 7
• Avoid sedating antihistamines in elderly or at-risk patients due to fall and cognitive impairment risk 1, 8
• Do not continue suspected causative medications in the presence of constitutional symptoms (fever, lymphadenopathy, elevated transaminases) even if rash is mild 2

Dermatology Referral Indications

Refer urgently if: 1, 8

• No response to initial treatment after 2 weeks 1, 8
• Diagnostic uncertainty exists 1
• Autoimmune skin disease suspected based on clinical pattern 1, 8
• Rash progresses despite appropriate management 1

Alternative Pain Management

For future pain control, avoid all NSAIDs if naproxen hypersensitivity confirmed 4:

• Cross-reactivity between propionic acid NSAIDs (naproxen, ibuprofen, ketoprofen) can occur but is not universal 4
• Consider acetaminophen as first-line alternative 4
• If NSAIDs required, patch testing can identify safe alternatives within the same class 4

Follow-Up Monitoring

• Reassess in 3-5 days to confirm rash improvement after naproxen discontinuation 3
• Monitor weekly if Grade 2 until improvement to Grade 1 8
• Immediate consultation required if fever develops, mucosal involvement appears, or systemic symptoms emerge 2, 1