HEALTH TOPICS 
Psoriasis
What Is It?
Psoriasis is a chronic skin disorder that causes scaling and inflammation.
Psoriasis may develop as a result of an abnormality in the body's immune system. The immune system normally fights infection and allergic reactions.
To continue reading this article, you must log in.
Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.
- Research health conditions
- Check your symptoms
- Prepare for a doctor's visit or test
- Find the best treatments and procedures for you
- Explore options for better nutrition and exercise