Oral Systemic Therapy for Moderate‑to‑Severe Dermatitis

Initial Symptomatic Management

Switching from sedating antihistamines (e.g., diphenhydramine) to non‑sedating agents such as cetirizine 10 mg daily or loratadine 10 mg daily provides 24‑hour itch control with reduced sedation risk. 3
Prolonged use of sedating antihistamines should be avoided, especially in individuals who drive or operate machinery. 3

Systemic agents are indicated when optimized topical regimens (high‑potency corticosteroids, calcineurin inhibitors) and/or phototherapy fail to control disease. 1
When the skin disease causes significant physical, emotional, or social impairment, systemic therapy is warranted. 1
Extensive chronic dermatitis in elderly or infirm patients also meets criteria for systemic treatment. 4

Cyclosporine is the preferred first‑line oral systemic medication for refractory dermatitis. 1
Recommended dose: 3–6 mg/kg/day divided into two doses. 1
Clinical response typically occurs within ≈ 3 weeks. 4
Treatment should be limited to short‑term courses of 3–4 months because of nephrotoxicity and hypertension risk. 6
Contraindications include abnormal renal function, uncontrolled hypertension, and current or past malignancy. 4
Monitoring: obtain baseline and periodic serum creatinine and blood pressure; if creatinine rises >25 % above baseline, reduce dose by 1 mg/kg/day for 2–4 weeks. 1

Dose range: 7.5–25 mg once weekly (adult), initiated at low dose and titrated upward. 1
Improvement is usually seen within ≈ 2 weeks. 4
Folate supplementation should be prescribed concomitantly. 1
Contraindications: pregnancy, breastfeeding, significant hepatic injury, anemia, leukopenia, or thrombocytopenia. 4
Monitoring plan: baseline complete blood count (CBC), liver function tests, and serum creatinine; repeat CBC 5–6 days after the first dose and conduct regular liver enzyme surveillance. 1
Major risks include acute marrow suppression, cumulative‑dose hepatotoxicity, and pneumonitis. 6

Dose range: 1–3 mg/kg/day. 1
Clinical response generally occurs within ≈ 4 weeks. 4
Dosing may be individualized based on thiopurine methyltransferase (TPMT) enzyme activity testing. 1
Contraindications: pregnancy, breastfeeding, severe anemia, and significant hepatic injury. 4
Monitoring: baseline CBC, serum creatinine, and electrolytes; ongoing CBC and liver function assessments during therapy. 1

May be considered as a variably effective alternative when first‑ and second‑line agents are unsuitable. 1
Typical dose: 1–4 mg/kg/day. 1

Systemic corticosteroids should be avoided for chronic disease management; reserve them for acute severe flares as a short‑term bridge to steroid‑sparing agents. 1

All systemic immunomodulators (cyclosporine, methotrexate, azathioprine, mycophenolate) are contraindicated in pregnancy; reliable contraception must be ensured for women of child‑bearing potential. 4

Once therapeutic response is achieved, taper each immunomodulatory agent to the minimal effective dose. 1

Continue aggressive emollient therapy (at least twice daily) alongside systemic agents to reduce the required medication dose. 1
If a secondary bacterial infection is suspected (e.g., warmth, purulent discharge, crusting), add an oral antibiotic such as tetracycline for a minimum of two weeks. 8