Obsessive-compulsive disorder (OCD) is a mental illness that causes repeated unwanted thoughts or sensations (obsessions) or the urge to do something over and over again (compulsions). Some people can have both obsessions and compulsions. They interfere with your life, but you cannot control or stop them.

The cause of OCD is unknown. Factors such as genetics, brain biology and chemistry, and your environment may play a role.

The obsessive-compulsive disorder usually begins when you are a teen or young adult. Boys often develop OCD at a younger age than girls. Risk factors for OCD include family history, brain structure and functioning or childhood trauma, such as child abuse. Children may develop OCD or OCD symptoms following a streptococcal infection; Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS).

People with OCD may have symptoms of obsessions, compulsions, or both:

  • Obsessions are repeated thoughts, urges, or mental images that cause anxiety. They may involve things such as fear of germs or contamination, fear of losing or misplacing something, worries about harm coming towards yourself or others, unwanted forbidden thoughts involving sex or religion, aggressive thoughts towards yourself or others, needing things lined up exactly or arranged in a particular, precise way.
  • Compulsions are behaviours that you feel like you need to do repeatedly to reduce your anxiety or stop the obsessive thoughts. Common compulsions include excessive cleaning and handwashing, constantly checking on things, such as whether the door is locked or the oven is off, and compulsive counting and ordering and arranging things in a precise way.

To diagnose OCD, your doctor may do a physical exam and blood tests to ensure something else isn’t causing your symptoms. They will also talk with you about your feelings, thoughts, and habits. The main treatments for obsessive-compulsive disorder (OCD) are cognitive behavioural therapy, medicines, relaxation, neuromodulation, transcranial magnetic stimulation, and caregiver interventions.

There’s no sure way to prevent obsessive-compulsive disorder. However, getting treatment as soon as possible may help avoid OCD from worsening and disrupting activities and your daily routine.