• Psoriasis is a chronic autoimmune disease that causes the skin to produce too many skin cells. This causes the skin to become thick, red, and scaly. Psoriasis can affect any part of the body, but it most commonly affects the scalp, elbows, knees, and lower back.

• Red, scaly patches of skin: This is the most common symptom of psoriasis. The patches can be small or large, and they can be anywhere on the body.
• Itch: The patches of skin may be itchy, but not always.
• Pain: The patches of skin may be painful, especially if they are scratched.
• Scaling: The patches of skin may be covered in scales, which are made up of dead skin cells.
• Joint pain: Psoriasis can also cause joint pain, a condition known as psoriatic arthritis.

• Genetics: Psoriasis is more common in people with a family history of the condition.
• Immune system: Psoriasis is thought to be caused by an overactive immune system.
• Infections: Some infections, such as strep throat, can trigger a psoriasis flare-up.
• Medications: Some medications, such as lithium and beta-blockers, can trigger a psoriasis flare-up.
• Stress: Stress can trigger a psoriasis flare-up.