What oral glucocorticoid (e.g., prednisone) dose and duration is appropriate for an adult without diabetes, hypertension, or active infection who has a diffuse pruritic rash that began after a recent viral respiratory illness?

Oral Prednisone for Post-Viral Diffuse Pruritic Rash

For an adult with a diffuse pruritic rash following a viral respiratory infection, prescribe oral prednisone 0.5–1 mg/kg/day (typically 40–60 mg daily for a 70 kg patient) as a single morning dose, tapered over 2 weeks. 1

Dosing Algorithm

Initial Dose Selection

• Start with prednisone 0.5–1 mg/kg/day based on rash severity and extent of body surface area involvement. 1
• For moderate pruritus limiting daily activities: use 0.5 mg/kg/day (approximately 35–40 mg for a 70 kg patient) 1
• For severe, generalized pruritus significantly impairing function: use 1 mg/kg/day (approximately 60–70 mg for a 70 kg patient) 1
• Administer as a single morning dose before 9 AM to align with physiologic cortisol rhythm and minimize hypothalamic-pituitary-adrenal axis suppression. 2

Duration and Taper Protocol

• Treat for a short course of 1–2 weeks to minimize adverse effects, with mandatory tapering regardless of duration. 1
• Example 2-week taper for 60 mg starting dose:
  • Days 1–3: 60 mg daily
  • Days 4–6: 40 mg daily
  • Days 7–9: 20 mg daily
  • Days 10–12: 10 mg daily
  • Days 13–14: 5 mg daily, then stop 1
• Tapering is essential even for short courses to prevent adrenal insufficiency, particularly in patients receiving >5 mg/day prednisone equivalent. 3

Critical Precautions

Contraindications and Risk Assessment

• Do not use systemic corticosteroids if the patient has active infection, uncontrolled diabetes, or severe hypertension without addressing these comorbidities first. 3
• Screen for diabetes, glucose intolerance, cardiovascular disease, peptic ulcer disease, and osteoporosis risk before initiating therapy 3
• Patients with these comorbidities require tight monitoring to manage the risk-benefit ratio. 3

Adverse Effects to Monitor

• Short-term effects (1–2 weeks): hyperglycemia, hypertension, gastritis, weight gain, and mood changes 1
• Risk of rebound and increased disease severity upon discontinuation if tapered too rapidly 1
• Even short courses (3–7 days) carry risks of bone density loss, hypertension, and gastrointestinal complications. 4

Prophylactic Measures

• Consider profilaxis with a proton pump inhibitor when using high doses (≥1 mg/kg/day) or treatment duration >2 weeks to prevent peptic ulcer disease. 1
• Provide calcium and vitamin D supplementation for courses exceeding 2 weeks 1, 2
• For treatment >3 weeks at doses >30 mg/day, consider Pneumocystis jirovecii pneumonia prophylaxis. 1

Common Pitfalls to Avoid

Dosing Errors

• Do not use actual body weight in overweight patients; calculate ideal body weight to avoid excessive steroid exposure and increased side effects. 2
• Do not administer evening doses, as this disrupts normal cortisol rhythm and increases HPA axis suppression. 2

Tapering Mistakes

• Never abruptly stop prednisone after any course; always implement a gradual taper to allow adrenal recovery. 1, 2
• If symptoms worsen during taper, return to the previous effective dose and slow the taper rate. 1
• Patients on chronic medium-dose glucocorticoids (>5 mg/day) are at risk of adrenal suppression and require stress-dose coverage during acute illness 3

Inappropriate Use

• Do not prescribe systemic corticosteroids for mild, localized rashes; use topical corticosteroids instead. 2
• Recognize that post-viral rashes are typically self-limited; reserve systemic steroids for cases where pruritus significantly impairs quality of life 1

Monitoring During Treatment

• Check fasting blood glucose at baseline and during treatment, especially in elderly patients who have higher risk of steroid-induced diabetes 5
• Monitor blood pressure regularly, as hypertension occurs in 3–28% of patients on medium-dose glucocorticoids 3
• Assess for signs of infection, as even short courses can increase infection risk 3, 4

Evidence Quality Note

The dosing recommendations are based on consensus guidelines from the Society for Immunotherapy of Cancer and American Society of Clinical Oncology for pruritic skin reactions, which provide moderate-quality evidence for the 0.5–1 mg/kg/day range with 2-week taper. 1 The American Academy of Pediatrics supports similar weight-based dosing algorithms, though pediatric data cannot be directly extrapolated to adults 2. The emphasis on short-course therapy (1–2 weeks) reflects growing evidence that even brief steroid exposure carries significant adverse event risk. 4