Obsessive-compulsive disorder (OCD) features a pattern of unwanted thoughts and fears (obsessions) that lead you to do repetitive behaviors (compulsions). These obsessions and compulsions interfere with daily activities and cause significant distress.
You may try to ignore or stop your obsessions, but that only increases your distress and anxiety. Ultimately, you feel driven to perform compulsive acts to try to ease your stress. Despite efforts to ignore or get rid of bothersome thoughts or urges, they keep coming back. This leads to more ritualistic behavior — the vicious cycle of OCD.
OCD often centers around certain themes — for example, an excessive fear of getting contaminated by germs. To ease your contamination fears, you may compulsively wash your hands until they're sore and chapped.
If you have OCD, you may be ashamed and embarrassed about the condition, but treatment can be effective.
 

Symptoms

Obsessive-compulsive disorder usually includes both obsessions and compulsions. But it's also possible to have only obsession symptoms or only compulsion symptoms. You may or may not realize that your obsessions and compulsions are excessive or unreasonable, but they take up a great deal of time and interfere with your daily routine and social, school or work functioning.
Obsession symptoms
OCD obsessions are repeated, persistent and unwanted thoughts, urges or images that are intrusive and cause distress or anxiety. You might try to ignore them or get rid of them by performing a compulsive behavior or ritual. These obsessions typically intrude when you're trying to think of or do other things.

Obsessions often have themes to them, such as:

Fear of contamination or dirt
Doubting and having difficulty tolerating uncertainty
Needing things orderly and symmetrical
Aggressive or horrific thoughts about losing control and harming yourself or others
Unwanted thoughts, including aggression, or sexual or religious subjects
Examples of obsession signs and symptoms include:

Fear of being contaminated by touching objects others have touched
Doubts that you've locked the door or turned off the stove
Intense stress when objects aren't orderly or facing a certain way
Images of driving your car into a crowd of people
Thoughts about shouting obscenities or acting inappropriately in public
Unpleasant sexual images
Avoidance of situations that can trigger obsessions, such as shaking hands
Compulsion symptoms
OCD compulsions are repetitive behaviors that you feel driven to perform. These repetitive behaviors or mental acts are meant to reduce anxiety related to your obsessions or prevent something bad from happening. However, engaging in the compulsions brings no pleasure and may offer only a temporary relief from anxiety.
You may make up rules or rituals to follow that help control your anxiety when you're having obsessive thoughts. These compulsions are excessive and often are not realistically related to the problem they're intended to fix.
As with obsessions, compulsions typically have themes, such as:

Washing and cleaning
Checking
Counting
Orderliness
Following a strict routine
Demanding reassurance
Examples of compulsion signs and symptoms include:

Hand-washing until your skin becomes raw
Checking doors repeatedly to make sure they're locked
Checking the stove repeatedly to make sure it's off
Counting in certain patterns
Silently repeating a prayer, word or phrase
Arranging your canned goods to face the same way.