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Obsessive-Compulsive Disorder (OCD) - Topic Overview

Obsessive-compulsive disorder (OCD) is a type of mental illness that causes repeated unwanted thoughts. To get rid of the thoughts, a person with OCD does the same tasks over and over. For example, you may fear that everything you touch has germs on it. So to ease that fear, you wash your hands over and over again.

Experts don't know the exact cause of obsessive-compulsive disorder. Research suggests that there may be a problem with the way one part of the brain sends information to another part. Not having enough of a brain chemical called serotonin may help cause the problem.

Some experts believe that a problem related to streptococcal infections, such as strep throat and scarlet fever, can suddenly bring on the disorder or make its symptoms worse in some children.

Symptoms of obsessive-compulsive disorder tend to come and go over time and range from mild to severe. Anxiety is the most common symptom. For example, you may have an overall sense that something terrible will happen if you don't do a certain task, such as check again and again to see if the stove is on. If you fail to check, you may suddenly feel tense or anxious or have a nagging sense that you left something undone.

Symptoms of the disorder include:

  • Obsessions. These are unwanted thoughts, ideas, and impulses that you have again and again. They won't go away. They get in the way of your normal thoughts and cause anxiety or fear. The thoughts may be sexual or violent, or they may make you worry about illness or infection. Examples include:
    • A fear of harm to yourself or a loved one.
    • A driving need to do things perfectly or correctly.
    • A fear of getting dirty or infected.
  • Compulsions. These are behaviors that you repeat to try to control the obsessions. Some people have behaviors that are rigid and structured, while others have very complex behaviors that change. Examples include:
    • Washing, or checking that something has been done.
    • Counting, often while doing another compulsive action, such as hand-washing.
    • Repeating things or always moving items to keep them in perfect order.
    • Hoarding.
    • Constant praying.

The obsessions or compulsions usually take up a lot of time—more than 1 hour a day. They greatly interfere with your normal routine at work or school, and they affect social activities and relationships.

Sometimes people may understand that their obsessions and compulsions aren't real. But at other times they may not be sure, or they may believe strongly in their fears.

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