Obsessive-compulsive and related disorders

This group of conditions is united by a pattern of repetitive thoughts, urges, or behaviors that are difficult to control and cause significant distress or disruption to daily life. They are more common than many people realize and respond well to the right treatment.

What are obsessive-compulsive and related disorders?

These conditions were historically grouped with anxiety disorders, but are now recognized as a distinct category with their own characteristics and treatment approaches. What links them is repetition—whether that is repetitive intrusive thoughts, repetitive checking and cleaning rituals, repetitive preoccupations with appearance or possessions, or repetitive body-focused behaviors like hair pulling or skin picking.

The repetition in these conditions is not simply a habit or a quirk. It typically causes meaningful distress or takes up significant time, interfering with work, relationships, and everyday functioning. People with these conditions are generally aware that their thoughts or behaviors are excessive—but that awareness does not make them easy to stop.

Understanding obsessions and compulsions

Two concepts run through several of these disorders and are worth understanding clearly.

Obsessions

Obsessions are recurrent, persistent thoughts, urges, or mental images that intrude into a person's mind uninvited. They are experienced as unwanted and cause anxiety or distress. Common themes include contamination, harm, symmetry, and forbidden or taboo thoughts (such as aggressive, sexual, or religious content). Having an intrusive thought does not reflect a person's character or intentions—these thoughts are ego-dystonic, meaning they feel alien to the person's sense of self.

Compulsions

Compulsions are repetitive behaviors or mental acts performed in response to an obsession, or according to rigid rules that feel necessary to follow. They may include physical actions—such as washing, checking, arranging, or tapping—or internal mental acts such as counting, repeating phrases, or mentally reviewing past events. Compulsions are aimed at reducing the anxiety caused by an obsession or preventing a feared outcome. They provide temporary relief but ultimately reinforce the cycle.

Types of obsessive-compulsive and related disorders

Obsessive-Compulsive Disorder (OCD)

OCD involves obsessions, compulsions, or both, which are time-consuming—typically taking more than an hour a day—and cause significant distress or interfere with daily life. Common presentations cluster around contamination and cleaning, symmetry and ordering, forbidden or taboo thoughts, and fears of harm or the need to check. The content of obsessions varies widely between people, and OCD can look very different from one person to the next.

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Body Dysmorphic Disorder (BDD)

BDD is characterized by a persistent preoccupation with one or more perceived flaws in physical appearance that are not observable to others or appear minor. The person engages in repetitive behaviors in response—such as mirror checking, excessive grooming, seeking reassurance, or comparing themselves to others. BDD causes significant distress and commonly leads to avoidance of social situations. A subtype called muscle dysmorphia involves a preoccupation with not being muscular enough.

Hoarding Disorder

Hoarding disorder involves persistent difficulty discarding or parting with possessions, regardless of their actual value, driven by a strong perceived need to save them. Over time, this leads to an accumulation of items that clutter living spaces to the point where they can no longer be used as intended. The difficulty discarding causes significant distress or impairment, and the condition is distinct from OCD—it has its own course, features, and treatment approach.

Trichotillomania (Hair-Pulling Disorder)

Trichotillomania involves recurrent, compulsive pulling of one's own hair—from the scalp, eyebrows, eyelashes, or other areas—resulting in noticeable hair loss. People typically make repeated attempts to stop or reduce the behavior without success. Hair pulling may occur in a focused, deliberate way or automatically without full awareness. It is not a form of self-harm but is driven by urges, tension, or a need for sensory stimulation or relief.

Excoriation (Skin-Picking) Disorder

Excoriation disorder involves recurrent picking of the skin—at the face, arms, or elsewhere—to the point of causing skin lesions, sores, or scarring. Like trichotillomania, it involves repeated failed attempts to stop and is driven by urges or the temporary relief that picking provides. Both conditions are sometimes called body-focused repetitive behaviors (BFRBs) and respond to similar treatments.

A note on insight

For OCD, body dysmorphic disorder, and hoarding disorder, the degree to which a person recognizes that their beliefs are not accurate varies and is clinically important. Some people have good insight—they understand that their obsessions or preoccupations are excessive or unfounded, even if they cannot easily dismiss them. Others have poor insight and are largely convinced that their fears or beliefs are accurate. In rare cases, the beliefs are held with complete conviction and may appear indistinguishable from delusions.

Lower insight is associated with greater distress and a more challenging treatment course. It does not mean a person is at fault or cannot improve with support.

Signs to look out for

These conditions can look very different from one another, but some patterns worth paying attention to include:

  • Spending substantial time each day on repetitive thoughts, rituals, or behaviors that feel difficult or impossible to resist
  • Distress when rituals or routines cannot be completed, or when trying to resist compulsions
  • Avoiding people, places, or situations because of fear of triggering obsessions or compulsions
  • Preoccupation with physical appearance, perceived flaws, or the belief that something is deeply wrong with how one looks
  • Difficulty discarding items even when they are no longer useful, leading to significant clutter
  • Noticeable hair loss or skin damage from repetitive pulling or picking, accompanied by difficulty stopping
  • Significant shame or secrecy around the behaviors, leading to concealment from others

What helps

These conditions are treatable, and most people see meaningful improvement with the right support. Effective approaches include:

  • Exposure and response prevention (ERP)—the gold-standard therapy for OCD, involving gradual, supported exposure to feared situations while refraining from compulsions; also effective for BDD
  • Cognitive behavioral therapy (CBT)—helps challenge distorted beliefs and change maintaining behaviors across the full range of conditions in this group
  • Habit reversal training (HRT)—a structured behavioral approach specifically effective for trichotillomania and excoriation disorder, targeting awareness of triggers and substituting alternative responses
  • Medication—SSRIs are the most evidence-based medication option across this group; higher doses are typically required for OCD than for depression
  • Decluttering and CBT for hoarding—specialized CBT for hoarding disorder addresses the beliefs and emotional attachments that drive accumulation, often alongside practical support

Many of these conditions are associated with shame, which can delay help-seeking by years. Treatment works—and the sooner support is sought, the better the outcomes tend to be.

When to seek help

Consider speaking to a GP or mental health professional if repetitive thoughts or behaviors are taking up significant time, causing distress, or getting in the way of daily life—whether at work, in relationships, or at home. You do not need to have a severe or textbook presentation to deserve support.

It is also worth seeking help if you recognize these patterns in someone you care about. Many people with these conditions minimize how much they are affected or feel too ashamed to ask for help themselves.