Psoriasis: What It Is, Symptoms, Causes, and When to See a Doctor
Medically reviewed by Dr. Yousef Binamer — Consultant
Psoriasis is a chronic, immune-mediated inflammatory skin disease, meaning the immune system plays a central role in it. Its classic sign is thick, scaly plaques that are often red and covered with silvery scales. Psoriasis is not an infection and does not spread from person to person through touch or contact. It is a chronic condition that tends to appear and recede over time, and its severity and location vary from person to person.
What are the main symptoms of psoriasis, and where do they appear?
The clearest sign of psoriasis is thick, scaly plaques. According to data from the Saudi Arabia Psoriasis Registry (PSORSA), published in the journal Dermatology and Therapy — which included 482 patients across 40 hospitals — the most commonly affected areas were:
- The arms (upper limbs) and legs (lower limbs).
- The scalp and the trunk.
- Nails, the genital area, and the face were also affected, at lower rates.
The extent and severity of involvement differ from person to person, and psoriasis may be limited to one area or extend to several.
What are the types of psoriasis?
Psoriasis comes in several forms, including plaque, guttate, pustular, inverse, and erythrodermic. By far the most common is plaque psoriasis, which accounted for about 94% of patients in the Saudi registry; the other types were much less frequent.
What causes psoriasis, and is it hereditary?
Psoriasis is an immune-mediated disease, which means the immune response drives skin cells to renew faster than usual, so they build up into plaques and scales. Heredity has a recognized role: about 17% of patients in the Saudi registry reported a family history of psoriasis. The mean age at diagnosis in the registry was around 32 years, suggesting it often begins in early adulthood. Having a family history does not make psoriasis inevitable, but it is one of the factors a doctor considers during assessment.
Why is psoriasis considered a whole-body condition?
Psoriasis can occur alongside other health conditions. In the Saudi registry, psoriatic arthritis was the most common comorbidity among patients who had associated conditions, followed by diabetes and hypertension.
Psoriatic arthritis can cause joint pain and stiffness in some people with psoriasis, so assessment includes overall health as well as the skin. Not everyone with psoriasis develops an associated condition.
Is psoriasis contagious?
No. Psoriasis is not contagious at all. It does not spread through shaking hands, sharing items, swimming, or food. It is tied to a person's own immune system, and there is no risk in being around someone who has it.
When should you see a doctor?
It is sensible to see a dermatologist in situations such as:
- Scaly plaques or recurring, unexplained skin patches appear.
- Symptoms persist, spread, or affect quality of life and self-confidence.
- You feel joint pain or stiffness along with psoriasis — it is worth mentioning to your doctor, since psoriasis can be linked to psoriatic arthritis.
The dermatologist chooses psoriasis care according to its type, severity, and location, as well as the patient's overall health and family history.
Saudi national registry data
The Saudi Arabia Psoriasis Registry (PSORSA) is the first disease-based psoriasis registry in the Middle East and North Africa (MENA) region. It gathered data from 482 patients across 40 hospitals in different parts of the Kingdom, providing a local picture of patient characteristics and care patterns.
Source: A study of the demographics, clinical characteristics, and treatment patterns of psoriasis patients from the Saudi Arabia Psoriasis Registry (PSORSA), published in Dermatology and Therapy (2025) — DOI: 10.1007/s13555-025-01436-9
Frequently asked questions
Is psoriasis contagious?
No. Psoriasis is not contagious and does not spread through touch, shared items, or swimming. It is an immune-related condition tied to the person themselves.
Is psoriasis linked to the joints?
Yes. Psoriasis can be linked to psoriatic arthritis, which causes joint pain and stiffness. Tell your doctor if you have joint pain alongside psoriasis.
What is the most common type of psoriasis?
Plaque psoriasis is the most common, accounting for about 94% of patients in the national Saudi registry. It is characterized by thick, scaly plaques.
Is psoriasis hereditary?
Heredity plays a role: about 17% of patients in the Saudi registry reported a family history of psoriasis. However, a family history does not make the condition inevitable.
At what age does psoriasis usually begin?
It varies, but the mean age at diagnosis in the national Saudi registry was around 32 years, suggesting it often begins in early adulthood.