What is the treatment for itching caused by contact dermatitis or allergens?

Treatment of FCM-Induced Itching

First-Line Topical Management

For FCM (ferric carboxymaltose)-induced itching, immediately apply topical moisturizers containing urea or polidocanol, followed by mid-to-high potency topical corticosteroids such as prednicarbate 0.02% cream or clobetasol 0.05% for moderate to severe symptoms. 1

Emollient and Moisturizer Therapy

• Apply skin moisturizers and urea- or polidocanol-containing lotions as the foundation of treatment to soothe pruritus 1
• Best applied after bathing when skin is still slightly damp to improve hydration and penetration 2
• Avoid alcohol-containing lotions or gels in favor of oil-in-water creams or ointments 1
• Apply emollients at least once daily to affected areas 1

Topical Corticosteroid Application

• For mild itching (grade 1): Apply hydrocortisone topically to affected areas not more than 3-4 times daily 3
• For moderate symptoms (grade 2): Use prednicarbate cream 0.02% as a short-term topical steroid 1
• For severe symptoms (grade 3): Escalate to clobetasol propionate 0.05% for up to 2 weeks, which achieves clear or almost clear skin in 67.2% of patients with severe dermatitis 4, 5
• Apply topical steroids to affected areas only, not to surrounding normal skin 3

Alternative Topical Agents

• If topical corticosteroids are contraindicated or ineffective, apply pimecrolimus 1% cream or tacrolimus 0.1% ointment twice daily to affected areas 1, 6
• These calcineurin inhibitors are particularly useful for sensitive skin areas where prolonged steroid use is inadvisable 1
• Stop treatment when signs and symptoms such as itching, rash, and redness resolve 6

Systemic Antihistamine Therapy

For grade 2/3 pruritus that persists despite topical therapy, add oral H1-antihistamines such as cetirizine 10mg daily, loratadine 10mg daily, fexofenadine 180mg daily, or clemastine for relief of itching. 1

Antihistamine Selection and Dosing

• Non-sedating antihistamines (cetirizine, loratadine, fexofenadine) provide relief primarily through their sedative properties rather than histamine blockade in drug-induced reactions 1, 7
• Sedating antihistamines may be used at night to break the itch-scratch cycle and improve sleep quality 1, 7
• Evidence for antihistamines in non-histamine-mediated pruritus is limited, but they may provide symptomatic relief through central sedation 1, 8, 9

Critical Management Steps

Skin Care Practices

• Avoid dehydrating body care such as hot showers and excessive use of soaps 1
• Substitute all soaps and detergents with emollients to prevent further irritation 2, 4
• Do not apply topical treatments to broken, irritated, or infected skin 2
• Avoid application to face, eyes, or mucous membranes 2

Monitoring and Reassessment

• Reassess after 2 weeks; if no improvement or worsening occurs, escalate therapy 1, 2
• Monitor for signs of secondary bacterial infection (crusting, weeping), which requires anti-staphylococcal antibiotics 1
• If symptoms persist beyond 6 weeks despite appropriate treatment, consider alternative diagnoses or refer to dermatology 6

Common Pitfalls to Avoid

• Do not use topical antihistamines (such as diphenhydramine gel) as they can cause allergic contact dermatitis and drowsiness from systemic absorption 1
• Avoid prolonged continuous use of potent topical steroids on the same area, which can lead to skin atrophy and steroid addiction/withdrawal 1
• Do not substitute oral antihistamines for proper topical management, as they do not directly reduce pruritus in non-histamine-mediated reactions 9
• Avoid washing affected areas with harsh soaps, detergents, or very hot water 2, 4
• Do not apply occlusive dressings over treated areas unless specifically indicated 6

Escalation for Refractory Cases

If itching persists despite 2-4 weeks of appropriate topical and systemic therapy:

• Consider short-term oral systemic steroids (prednisone tapered over 2-3 weeks) for severe, extensive symptoms 1, 5
• Refer to dermatology for consideration of phototherapy, systemic immunosuppressants (azathioprine, cyclosporine), or patch testing to rule out contact sensitization 4, 10
• Evaluate for secondary complications such as bacterial superinfection or contact dermatitis to topical medications themselves (particularly neomycin) 1