What to do if a rash develops after starting hydroxychloroquine (Plaquenil)?

Management of Hydroxychloroquine-Induced Rash

If a rash develops after starting hydroxychloroquine, the medication should be discontinued immediately and alternative treatment options should be considered due to the risk of progression to severe cutaneous adverse reactions.

Types of Hydroxychloroquine-Induced Skin Reactions

Hydroxychloroquine can cause various dermatological reactions, ranging from mild to severe:

• Common mild reactions: Pruritus and maculopapular eruptions
• Severe reactions:
  • Drug reaction with eosinophilia and systemic symptoms (DRESS)
  • Stevens-Johnson syndrome
  • Exacerbation of psoriasis or dermatomyositis

Evaluation of Hydroxychloroquine Rash

When a patient develops a rash after starting hydroxychloroquine, perform the following assessments:

1. Determine timing: Most hydroxychloroquine rashes develop within the first few weeks of treatment 1
2. Assess extent and severity:
   • Distribution (localized vs. widespread)
   • Presence of mucosal involvement
   • Associated symptoms (fever, lymphadenopathy)
3. Laboratory evaluation:
   • Complete blood count (look for eosinophilia)
   • Liver function tests
   • Renal function tests

Management Algorithm

Step 1: Immediate Actions

• Discontinue hydroxychloroquine immediately 2, 1, 3
• Document the reaction in the patient's medical record and allergy list

Step 2: Treat Based on Severity

For mild reactions (limited rash, no systemic symptoms):

• Topical corticosteroids (e.g., clobetasone butyrate) 4
• Oral antihistamines for pruritus
• Emollients for skin care

For moderate to severe reactions:

• Oral corticosteroids (e.g., prednisolone 10 mg) 4, 1
• Consider hospitalization if extensive rash or systemic symptoms present
• Supportive care including fluid management and temperature control

Step 3: Alternative Treatment Options

For patients requiring antimalarial therapy:

• Consider alternative disease-modifying antirheumatic drugs (DMARDs) based on the underlying condition:
  • Methotrexate 5
  • Sulfasalazine (with appropriate monitoring) 4
  • Leflunomide 4
  • Biological agents if appropriate

Special Considerations

High-Risk Patients

Patients with the following conditions may be at higher risk for hydroxychloroquine-induced rashes:

• History of drug allergies
• Dermatomyositis (particularly with TIF1γ or NXP2 antibodies) 6
• Psoriasis (hydroxychloroquine can trigger or exacerbate psoriasis) 5

Follow-up Care

• Reassess skin condition 2-4 weeks after discontinuation of hydroxychloroquine
• Consider dermatology consultation for persistent or severe rashes
• Patch testing may be considered to confirm hydroxychloroquine as the causative agent

Prevention and Patient Education

When starting hydroxychloroquine:

• Inform patients about potential skin reactions 2
• Instruct patients to report any skin changes promptly
• Provide written information about warning signs that require immediate medical attention

Pitfalls and Caveats

1. Don't rechallenge: Avoid reintroducing hydroxychloroquine in patients who have experienced significant skin reactions, as this may trigger more severe reactions

2. Don't delay discontinuation: Even mild rashes can progress to severe reactions if the medication is continued 3

3. Don't miss systemic involvement: Always assess for signs of systemic reactions (fever, lymphadenopathy, organ involvement) that may indicate DRESS syndrome

4. Don't overlook alternative diagnoses: Consider other causes of rash, including viral exanthems and reactions to other medications

By promptly recognizing and appropriately managing hydroxychloroquine-induced rashes, serious complications can be avoided while ensuring continued effective treatment of the underlying condition with alternative medications.