Initial Treatment for Guttate Psoriasis
For guttate psoriasis, begin with low concentrations of topical coal tar (0.5-1.0%) or dithranol (0.1-0.25%), combined with narrowband ultraviolet B (UVB) phototherapy, while investigating and treating any underlying streptococcal infection with penicillin or erythromycin. 1, 2, 3
Understanding the Natural History
Guttate psoriasis is typically a self-limiting condition that resolves within 3-4 months in many cases. 1 However, up to 39-50% of patients may progress to chronic plaque psoriasis, which justifies active treatment rather than observation alone. 3, 4 This dual nature—potentially self-resolving yet with significant risk of chronicity—shapes the treatment approach toward early, effective intervention.
First-Line Treatment Algorithm
Topical Therapy (Start Here for All Patients)
Use LOW concentrations specifically because erupting guttate psoriasis is notably less tolerant of topical treatments compared to chronic plaque psoriasis. 1, 2
Coal tar: Start at 0.5-1.0% crude coal tar in petroleum jelly, increasing gradually every few days up to maximum 10% as tolerated. 1 Cruder extracts are messier but more effective than refined products. 1
Dithranol (anthralin): Begin at 0.1-0.25% concentration, doubling the concentration as response allows. 1 Consider short-contact mode (15-45 minutes daily) to minimize irritancy and staining. 1
Topical corticosteroids: Can be used in combination with other topicals for rapid symptom control. 3, 4 The 2024 systematic review found corticosteroids and calcipotriol creams had the most evidence for efficacy in guttate psoriasis. 3
Phototherapy (Most Robust Evidence)
Narrowband UVB phototherapy is especially helpful and has the strongest evidence base for guttate psoriasis. 2, 3 This is more practical than topical therapy alone when treating the widespread, numerous small lesions characteristic of this condition. 4
- Phototherapy should be supervised by adequately trained personnel with properly calibrated equipment. 1, 2
- Avoid commercial sunbeds (UVA-emitting), as they are rarely effective and may cause significant side effects. 1, 2
Investigate and Treat Streptococcal Infection
A critical and often overlooked component: A proportion of acute guttate psoriasis cases have evidence of streptococcal infection. 1
- Conduct investigations for streptococcal infection in all patients. 1
- Treat any persistent streptococcal infection with phenoxymethylpenicillin or erythromycin. 1
- The 2002 randomized study showed that adding penicillin to topical corticosteroids plus UVB reduced PASI scores effectively (from 5.9 to 1.0). 5
- Important caveat: Guttate psoriasis may be misdiagnosed as an antibiotic allergy, delaying appropriate treatment. 6
Second-Line Treatment (For Moderate-to-Severe or Refractory Cases)
If first-line therapy fails after adequate trial:
- Methotrexate or cyclosporine are recommended as second-line systemic options. 3, 4
- These require pretreatment assessment including full blood count, liver function tests, and serum creatinine, with ongoing monitoring. 7
Third-Line Treatment (Severe and Refractory Cases)
Special Considerations for Recurrent Disease
If repeated attacks of guttate psoriasis occur after well-documented episodes of tonsillitis, refer to otolaryngology for consideration of tonsillectomy. 1
Critical Pitfalls to Avoid
- Never use systemic corticosteroids as they can precipitate disease flares upon discontinuation. 2, 7
- Do not use high concentrations of tar or dithranol initially—guttate psoriasis is less tolerant than plaque psoriasis. 1, 2
- Avoid medications that may worsen psoriasis: lithium, chloroquine, beta-blockers, and NSAIDs. 8, 7
- Don't dismiss the possibility of streptococcal infection or confuse the eruption with antibiotic allergy. 6, 5