Psoriasis is thought to be an immune system problem that causes the skin to regenerate at faster than normal rates. In the most common type of psoriasis, known as plaque psoriasis, this rapid turnover of cells results in scales and red patches. Just what causes the immune system to malfunction isn't entirely clear. Researchers believe both genetics and environmental factors play a role. The condition is not contagious.
Psoriasis triggers:
Many people who are predisposed to psoriasis may be free of symptoms for years until the disease is triggered by some environmental factor. Common psoriasis triggers include:
• Infections, such as strep throat or skin infections
• Weather, especially cold, dry conditions
• Injury to the skin, such as a cut or scrape, a bug bite, or a severe sunburn
• Stress
• Smoking and exposure to secondhand smoke
• Heavy alcohol consumption
• Certain medications — including lithium, high blood pressure medications and antimalarial drugs
• Rapid withdrawal of oral or systemic corticosteroids
Courtesy: Mayo Clinic