Treatment of Guttate Psoriasis
For guttate psoriasis, start with topical corticosteroids (moderately potent, grade III) combined with narrowband UVB phototherapy 3 times weekly, while screening for and treating any streptococcal infection with penicillin or erythromycin. 1
Initial Assessment and Workup
Before initiating treatment, obtain throat culture or rapid streptococcal antigen test, as guttate psoriasis is closely associated with preceding streptococcal pharyngitis occurring 3-4 weeks prior. 1 Consider anti-streptolysin O (ASO) titers if recent infection is suspected. 1
Critical pitfall: Do not confuse the guttate eruption with antibiotic allergy, as the rash typically appears 3-4 weeks after streptococcal infection, not immediately. 1
First-Line Treatment Algorithm
Topical Therapy
- Apply moderately potent topical corticosteroids (grade III) 2-3 times daily as the foundation of treatment. 1, 2
- Limit use to no more than 100g per month to avoid systemic absorption. 1
- Guttate psoriasis is less tolerant of aggressive topical treatment than chronic plaque psoriasis, so use lower concentrations initially. 3
Alternative topical options include:
- Coal tar 0.5-1.0% in petroleum jelly, increasing concentration as tolerated 1
- Dithranol (anthralin) 0.1-0.25% in short contact mode (15-45 minutes daily), though this requires careful application due to skin irritation 3, 1
- Calcipotriol cream, which has strong evidence for efficacy 4
Phototherapy (Most Robust Evidence)
Narrowband UVB phototherapy is the most effective treatment for guttate psoriasis and should be initiated early, especially for moderate-to-severe cases. 3, 4
- Start with 3 treatments per week initially, decreasing to 2 per week upon improvement 3, 1
- Initial dosing: 130-400 mJ/cm² based on skin type 3
- Increase subsequent doses by 15-65 mJ/cm² or 10% of initial dose 3
- Treatment courses typically last 8-10 weeks 3, 1
- Average 15-20 treatments needed to achieve clearance 3
- Remission rate of 38% at 1 year (superior to broadband UVB) 3
Important consideration: Phototherapy is more practical than topical therapy when treating the numerous small, widespread lesions characteristic of guttate psoriasis. 5
Antibiotic Therapy
If active streptococcal infection is documented, treat with phenoxymethylpenicillin or erythromycin. 3, 1 However, evidence suggests minimal connection between infection resolution and GP lesion remission. 4 One randomized trial showed no improvement in psoriasis when antibiotics were used, even with documented streptococcal colonization. 6
For recurrent guttate psoriasis following documented recurrent tonsillitis, refer to otolaryngology for consideration of tonsillectomy. 3, 1
Second-Line Treatment for Refractory Cases
If first-line therapy fails after 8-10 weeks, consider systemic immunosuppressants:
- Methotrexate: Start at 15 mg weekly, maximum 25-30 mg weekly 7, 4
- Cyclosporine: 2.5-5 mg/kg daily, limited to 1 year use due to nephrotoxicity risk 7, 4
Third-Line Treatment for Severe, Refractory Disease
For severe cases unresponsive to topical therapy and phototherapy, biologics may be considered, though evidence is limited for guttate psoriasis specifically. 4, 5
Critical Medications to AVOID
Never use systemic corticosteroids for guttate psoriasis. They can cause disease flare during taper and may precipitate pustular or erythrodermic psoriasis. 1, 7
Avoid commercial sunbeds (emitting UVA), as they are rarely effective and may cause premature skin aging and increased skin fragility. 3, 8
Natural History and Prognosis
Guttate psoriasis is self-limiting in most cases, resolving within 3-4 months without scarring. 1 However, 40-50% of cases may persist and progress to chronic plaque psoriasis. 4, 5 Given this high rate of progression, active treatment is generally recommended rather than watchful waiting, despite the possibility of spontaneous remission. 5