Psoriasis guidelines: assessment and systemic treatment
Severity assessment, comorbidity screening and principles for choosing phototherapy or systemic treatment.
Updated: 2026-09-13
Written for clinicians and medical students
This section is a teaching reference for doctors, residents and medical students. It is not patient guidance and not a substitute for clinical examination, and it must not be used for self treatment.
Assess beyond surface area
- Document objective extent and severity, symptoms, high-impact sites, functional effect and quality of life. Limited genital, facial, palmoplantar or scalp disease may still be severe [1].
- Screen for psoriatic arthritis at diagnosis and periodically. Ask about inflammatory joint pain, prolonged morning stiffness, dactylitis and enthesitis [1].
- Review cardiovascular risk, obesity, diabetes, smoking, alcohol, inflammatory bowel disease, mood and medication interactions as part of treatment selection [1,2].
Escalation principles
- Consider phototherapy or systemic therapy when topical treatment does not control disease with meaningful impact, when disease is extensive, or when high-impact sites are involved [1].
- Choose conventional, biologic or targeted treatment through shared decision-making based on phenotype, arthritis, comorbidity, pregnancy plans, infection risk, monitoring and access [2].
- Screen for tuberculosis and relevant viral infection before immunosuppressive therapy according to the selected agent and local epidemiology.