What are the recommended treatments and dosages for psoriasis?

Psoriasis Treatment and Dosage

Treatment Selection by Disease Severity

For mild psoriasis (less than 3% body surface area), topical corticosteroids are the first-line treatment, with combination calcipotriene/betamethasone dipropionate providing superior efficacy to either agent alone. 1, 2

Mild Psoriasis (< 3% BSA)

• Topical corticosteroids remain the primary treatment, with potency classified from Class 1 (ultrahigh-potency like clobetasol propionate 0.05%) to Class 7 (low-potency), applied for up to 4 weeks 1
• Clobetasol propionate 0.05% should be applied twice daily for optimal control, particularly in severe localized disease, as once-daily application shows reduced efficacy after 2 weeks 3, 4
• Calcipotriene 0.005%/betamethasone dipropionate 0.064% combination is recommended as the most effective topical regimen, with 69-74% of patients achieving clear or almost clear status at 52 weeks versus 27% with vehicle control 2
• Vitamin D analogs (calcipotriene) can be used alone or combined with corticosteroids, applied once or twice daily 1
• Topical calcineurin inhibitors (tacrolimus, pimecrolimus) are particularly useful for facial and intertriginous areas where corticosteroid side effects are problematic 1

Moderate to Severe Psoriasis (≥ 3% BSA)

For moderate to severe psoriasis, narrowband UVB phototherapy is recommended as first-line treatment before systemic agents, with methotrexate as the preferred initial systemic therapy if phototherapy fails. 1

Phototherapy Options

• Narrowband UVB is the first-line phototherapy with fewer side effects than PUVA 1
• PUVA (psoralen plus UVA) for adults: oral 8-methoxypsoralen followed by UVA exposure 2-3 times weekly, starting at 0.25-0.5 J/cm² and increasing by 0.25-0.5 J/cm² 5
• Bath PUVA may be used for generalized psoriasis: 50 mg of 8-methoxypsoralen in 100 L of water, 20-30 minutes pre-exposure 5
• Contraindications include lupus erythematosus, porphyria, xeroderma pigmentosum, and pregnancy 5

Systemic Therapies: Dosing and Monitoring

Methotrexate

• Initial dose: Start with test dose not exceeding 0.2 mg/kg body weight, then begin regular maintenance one week later if laboratory results are normal 5
• Maintenance dose: 15 mg weekly initially, maximum 25-30 mg weekly 1
• Monitoring: Weekly full blood count and liver function tests initially, then every 1-2 months once stable 5
• Contraindications: Pregnancy, breastfeeding, wish to father children, significant hepatic damage, anemia, leucopenia, thrombocytopenia 5
• Drug interactions: Avoid alcohol, salicylates, NSAIDs, co-trimoxazole, trimethoprim, probenecid, phenytoin, retinoids 5
• Contraception required: For at least one menstrual cycle after stopping in women; contraindicated in men wishing to father children 5

Cyclosporine

• Dose: 2.5-5 mg/kg daily 1
• Response time: Approximately 3 weeks 1
• Monitoring: Blood pressure and serum creatinine every 2 weeks for first 3 months, then monthly if stable 5
• Contraindications: Abnormal renal function, uncontrolled hypertension, previous or concomitant malignancy 5
• Drug interactions: Avoid aminoglycosides, amphotericin, trimethoprim, ketoconazole, phenytoin, rifampicin, isoniazid, NSAIDs 5

Acitretin

• Starting dose: 0.75 mg/kg/day (or 25-50 mg daily) for 2-4 weeks 5, 1
• Maintenance: Titrate down to 0.5 mg/kg/day or lowest effective dose 5
• Response time: As early as 3 weeks, particularly effective for pustular psoriasis 1
• Monitoring: Baseline and regular monitoring of CBC, lipid profile, liver function tests monthly for first 3 months, then every 3 months 5
• Contraindications: Pregnancy or wish to conceive within 2 years of stopping treatment, severely impaired liver or kidney function 5
• Contraception required: For at least 1 month before, during, and for at least 2 years after stopping treatment 5

Hydroxyurea

• Effective for severe psoriasis with about 60% response rate, safe for up to 1 year 5
• Monitoring: Full blood count and liver function tests regularly 5

Azathioprine

• Response rate of about 60%, but limited data available 5
• Monitoring: Blood pressure, urinalysis, serum creatinine, urea, and liver function tests every 2 weeks for first 3 months, then monthly 5

Biologic Therapies

For moderate to severe psoriasis not responding to traditional systemic agents, biologics provide superior efficacy, with IL-17 and IL-23 inhibitors showing higher response rates than TNF inhibitors. 2

Secukinumab (IL-17A antagonist)

• Adult dose: 300 mg subcutaneously at weeks 0,1,2,3, and 4, then every 4 weeks 6
• Pediatric dose (≥6 years): Weight-based: 75 mg for <50 kg, 150 mg for ≥50 kg at weeks 0,1,2,3,4, then every 4 weeks 6
• Some patients may respond to 150 mg dose 6

Ustekinumab (IL-12/23 antagonist)

• Adult dose ≤100 kg: 45 mg subcutaneously initially and at 4 weeks, then every 12 weeks 7
• Adult dose >100 kg: 90 mg subcutaneously initially and at 4 weeks, then every 12 weeks 7
• Pediatric dose (6-17 years): Weight-based: 0.75 mg/kg for <60 kg, 45 mg for 60-100 kg, 90 mg for >100 kg 7

Site-Specific Treatment Recommendations

Scalp Psoriasis

• Calcipotriene foam or calcipotriene/betamethasone dipropionate gel for 4-12 weeks 2
• Clobetasol propionate 0.05% solution applied twice daily for severe cases 3

Facial Psoriasis

• Topical tacalcitol ointment or calcipotriene combined with hydrocortisone for 8 weeks 2
• Avoid high-potency corticosteroids due to skin atrophy risk 1

Nail Psoriasis

• Topical vitamin D analogs combined with betamethasone dipropionate to reduce nail thickness, hyperkeratosis, onycholysis, and pain 2

Palmoplantar Psoriasis

• Topical maxacalcitol ointment as initial treatment 2
• Acitretin for palmoplantar pustular psoriasis 2
• Topical PUVA: 0.1% 8-methoxypsoralen in emollient, apply 30 minutes before UVA 2-3 times weekly 5

Combination Therapy Strategies

The addition of ultrahigh-potency topical corticosteroids to biologics accelerates clearance and improves outcomes in moderate to severe psoriasis. 5

• Etanercept + Class 1 topical corticosteroid for 12 weeks is recommended for moderate to severe psoriasis 5
• Adalimumab + calcipotriene/betamethasone for 16 weeks accelerates plaque clearance 5
• Methotrexate + topical calcipotriene provides additional clinical benefits 5
• Cyclosporine (2 mg/kg/day) + calcipotriene/betamethasone dipropionate ointment can be used for moderate to severe psoriasis 5
• Acitretin + calcipotriene enhances efficacy 5

Special Clinical Scenarios

Pustular Psoriasis

• Acitretin 25-50 mg daily is first-line therapy, with response as early as 3 weeks 1
• Methotrexate is especially useful in acute generalized pustular psoriasis 5

Psoriatic Erythroderma

• Methotrexate is particularly effective 5
• Cyclosporine achieves about 60% improvement even in erythrodermic psoriasis 5

Psoriatic Arthritis

• TNF-α inhibitors (etanercept, infliximab) are first-line biologic therapy 1
• Methotrexate is especially useful for psoriatic arthritis 5

Critical Safety Warnings

Systemic corticosteroids should be strictly avoided in psoriasis management except for three rare specific conditions, as withdrawal precipitates erythrodermic or generalized pustular psoriasis. 5, 1

The three exceptions are:

1. Persistent uncontrollable erythroderma causing metabolic complications 5
2. Generalized pustular psoriasis of von Zumbusch type if other drugs are contraindicated 5
3. Hyperacute psoriatic polyarthritis threatening severe irreversible joint damage 5

Common Pitfalls and Monitoring Requirements

• Methotrexate hepatotoxicity: Liver biopsy should be considered before starting or continuing methotrexate, though severe hepatic fibrosis cases have only occurred with much larger doses than currently used 5
• Cyclosporine nephrotoxicity: Reduce dose if serum creatinine increases; stop if deterioration doesn't respond to dose reduction 5
• PUVA photocarcinogenesis: Increased risk of squamous cell carcinoma and basal cell carcinoma in Caucasians with skin types I-III after 200 treatments; regular full skin examinations required 5
• Acitretin teratogenicity: Absolute contraception required for at least 1 month before, during, and for at least 2 years after stopping treatment due to prolonged storage in body 5
• Combination therapy toxicity: Acitretin and methotrexate can both cause hepatotoxicity; combine with extreme caution 5
• Phototherapy drug interactions: Decrease UVA dose by one-third if oral retinoids are started during PUVA therapy 5