Psoriasis

For a lay person:

Psoriasis is a long-term condition in which skin cells build up too quickly, forming raised, scaly patches. It is caused by an overactive immune system, often runs in families, and can be triggered by stress, infection, injury or some medicines. It tends to come and go, and some people also develop psoriatic arthritis.

For a trained medical person:

A chronic immune-mediated inflammatory disease driven by the IL-23/Th17 axis, with plaque, guttate, inverse, pustular and erythrodermic forms, and associations with arthritis and cardiometabolic disease. Diagnosis is clinical, with biopsy occasionally. Treatment is topical corticosteroids and vitamin D analogues for mild disease, then phototherapy, methotrexate or other systemic agents, and biologics for moderate to severe disease.

In Chinese medicine:

Liu and Tseng's textbook differentiates this condition into these patterns: Wind-Heat Accumulation at Skin Internally Attacking Ying Level; Internal Accumulation of Blood-Heat, Transforming into Dryness and Wind; Blood Stasis Obstructing Collaterals; Blood-Deficiency and Wind-Dryness; Blood-Dryness Damaging Yin. Treatment follows the pattern a patient presents with, not the Western diagnosis alone.

When to get help: Get urgent care for widespread red skin covering most of the body or sudden pus-filled spots with fever, as these are emergencies. Some oral herbal treatments for psoriasis have caused liver injury, so tell your doctor, especially if you take methotrexate or biologics.