Intrusive Thoughts: What They Are and When They Point to OCD

What an intrusive thought is

An intrusive thought is a thought, image or urge that arrives uninvited and feels out of step with you. It can be a doubt, a picture, a sudden impulse or a “what if.” Researchers who interviewed 777 university students at 15 sites in 13 countries found that 93.6% had at least one in the previous three months. Doubting thoughts were the most common kind; repugnant ones, such as sexual or blasphemous thoughts, were the least common but still turned up across the world.

Everyday examples include:

• “Did I lock the door? Did I turn off the stove?” even though you remember doing it
• a sudden picture of someone you love being hurt in an accident
• an urge to say something rude or embarrassing during a quiet, serious moment
• a flash of worry that you picked up germs from a door handle
• a thought during prayer or worship that feels disrespectful to your faith
• a passing “what if I lost control?” while driving or cooking

For most people, thoughts like these feel odd or unpleasant for a moment and then fade. They are not wishes, plans or predictions.

Why some thoughts stick

The thought itself is rarely the problem. What you make of it matters more. In a study of 270 students, Purdon and Clark found that two beliefs best predicted how often a person’s most upsetting intrusive thought kept coming back: believing they could act on it, and feeling they could not control it. Thoughts that clash with what you value tend to feel the most alarming, which is why a kind parent fears a thought about harm and a devout person fears a blasphemous one.

When a thought feels dangerous, it is natural to push it away, check, seek reassurance or avoid whatever set it off. Each of those brings a moment of relief. In OCD, that relief is what keeps the cycle turning.

When intrusive thoughts point to OCD

NIMH describes obsessions as repeated thoughts, urges or mental images that are intrusive, unwanted and make most people anxious. Compulsions are repetitive behaviors you feel driven to do, often in response to an obsession. NIMH is clear that not every repeated thought is an obsession and not every habit is a compulsion. People with OCD generally:

• can’t control their obsessions or compulsions, even when they know they are excessive
• spend more than 1 hour a day on them
• don’t enjoy the compulsions but may feel brief relief from anxiety afterward
• have significant problems in daily life because of them

OCD symptoms can come and go, often get worse under stress, and can change theme over time. NIMH also notes that OCD often appears alongside a mood or anxiety disorder, and that diagnosis can be hard because worry, anxiety and low mood overlap with other conditions.

Rituals you can see, and rituals you can’t

Some compulsions are visible: washing, cleaning, checking locks and appliances, arranging things until they feel right. Others happen silently. The APA practice guideline for OCD lists mental compulsions such as counting, praying, or reviewing actions, conversations or lists, done to feel safer or less anxious. NIMH lists praying or repeating words silently among common compulsions.

Other patterns that often keep OCD going:

• Avoidance. Staying away from places, objects or people that set off the thought. NIMH notes that people with OCD may avoid triggers or use alcohol or drugs to cope.
• Reassurance. Asking others, again and again, to confirm you are a good person or that nothing bad happened. The APA guideline notes that family members may give repeated reassurance or even do checks for you, which tends to feed the cycle.
• Searching. Hours spent online trying to prove to yourself that the thought means nothing.

Harm, sexual and religious themes

Some of the most distressing intrusive thoughts are about harming someone, about sex, or about religion. They are also some of the most common themes in OCD. NIMH’s list of common obsessions includes aggressive thoughts toward others or oneself; fear of losing control over one’s behavior; and unwanted, forbidden or taboo thoughts involving sex, religion or harm.

The APA guideline describes how these obsessions usually work: the person experiences them as alien to who they are, finds them morally abhorrent, resists them and often avoids situations that might trigger them. It notes that acting on such obsessional thoughts has not been reported in OCD, while people who fear losing control may build up extensive avoidance. Religious obsessions (sometimes called scrupulosity) often come with silent praying, repeating words or seeking reassurance about sin.

If you have thoughts like these, you may be afraid to say them out loud. NIMH notes that people with OCD often don’t tell their health care provider about their obsessions out of fear of judgment. Clinicians who treat OCD hear these themes regularly. You can start by describing the theme in general terms (“thoughts about harming someone I love”) and go into detail when you feel ready.

Intrusive thoughts after having a baby

Unwanted thoughts about harm coming to a new baby are very common. In a study that followed 763 pregnant women in British Columbia through the postpartum period, 95.8% reported unwanted thoughts of accidental harm (most often fears of the baby suffocating or dying suddenly) and 53.9% reported unwanted thoughts of intentional harm (most often thoughts of neglect). The thoughts were most intense in roughly the first two months, and for most people they faded or stopped by six months.

In the same research program, mothers who had unwanted thoughts of intentionally harming their infant were no more likely to report aggression toward the baby than mothers without these thoughts, and the same held for mothers with and without OCD. The APA guideline draws a key distinction: in postpartum OCD, harm thoughts feel foreign, are resisted and often lead to rituals or avoidance, and there is little risk of direct harm to the baby, though the rituals can get in the way of caring for and bonding with the baby and deserve treatment. Ideas of harm that arise in postpartum depression are different: they may feel justified, may not be strongly resisted and come with depressed mood, and steps to protect the baby may be needed.

Talk to a health care provider if the thoughts take up a lot of your day, if you are avoiding parts of baby care because of them, if you feel driven to check or repeat things, or if sadness, anxiety or exhaustion last longer than two weeks after birth, which NIMH lists as a possible sign of postpartum depression. See postpartum depression treatment.

Children and teens

According to NIMH, OCD symptoms usually start between late childhood and young adulthood. Many adults recognize that their rituals don’t make sense, but children may not, and they often fear that something terrible will happen if they don’t perform them. Parents or teachers are usually the first to notice: long bedtime routines, repeated questions, re-doing homework, or getting upset when a ritual is interrupted. NIMH also notes that children who suddenly develop or worsen OCD symptoms after a strep infection may be evaluated for a condition called PANDAS, so tell the pediatrician about a sudden change.

Willow & Stone sees preteens from age 10, teens and adults. For how OCD care works for younger patients here, see OCD treatment and medication management; for everyday worry versus a disorder, see teen anxiety vs normal worry.

When to get help

NIMH advises talking to a health care provider if you think you or your child may have OCD, because untreated symptoms can become severe and interfere with daily life. Signs it is time:

• the thoughts and rituals add up to more than an hour a day
• you are avoiding people, places or tasks you care about
• you rely on others for reassurance, or they have started doing rituals for you
• you also feel low, hopeless or constantly anxious
• the thoughts are getting in the way of caring for a baby, work, school or sleep

OCD is treatable. Exposure and response prevention (ERP) therapy and serotonin medications are the first-line treatments; compare medication, ERP and both. At Willow & Stone, Dr. Stacey Forbes, DNP, APRN, PMHNP-BC, a board-certified psychiatric-mental health nurse practitioner, evaluates OCD in a 90-minute integrative psychiatric evaluation by secure video and provides medication management. Ask us whether ERP is available through the practice or by referral.

When it is not an intrusive thought: get help now

An intrusive thought is unwanted. Some thoughts are different and need help right away:

• thoughts of ending your life, or of hurting someone, that feel like something you want or intend to do
• making a plan, researching ways to die, giving things away or saying goodbye, which NIMH lists among the warning signs of suicide
• thoughts of harm that feel justified or acceptable, or that come with deep hopelessness
• hearing or seeing things others don’t, or being sure of things that others say aren’t true

If any of these apply, call or text 988 (Suicide & Crisis Lifeline) at any hour, or call 911 if anyone is in immediate danger. OCD often comes with depression, and the APA guideline notes a higher rate of suicide attempts in people with OCD than in the general population, so thoughts of suicide always deserve a real conversation. If you can’t tell which kind of thought you are having, that is all right: a 988 counselor or your clinician can help you sort it out.

Common Questions

Sources

• Radomsky AS et al. Part 1: You can run but you can't hide: Intrusive thoughts on six continents. J Obsessive-Compulsive and Related Disorders 2014;3(3):269-279 (abstract, University of Nicosia research portal)
• Purdon C, Clark DA. Obsessive intrusive thoughts in nonclinical subjects, Part II. Behav Res Ther 1994;32(4):403-10
• NIMH: Obsessive-Compulsive Disorder: When Unwanted Thoughts or Repetitive Behaviors Take Over
• American Psychiatric Association: Practice Guideline for the Treatment of Patients With OCD (2007)
• Collardeau F et al. Prevalence and Course of Unwanted, Intrusive Thoughts of Infant-Related Harm. J Clin Psychiatry 2024;85(3):23m15145
• Fairbrother N et al. Postpartum Thoughts of Infant-Related Harm and OCD: Relation to Maternal Physical Aggression Toward the Infant. J Clin Psychiatry 2022;83(2):21m14006
• NIMH: Perinatal Depression
• NIMH: Warning Signs of Suicide

This article is general education, not a diagnosis or advice for your situation. Only a clinician who has evaluated you can diagnose a condition or recommend treatment. Do not start, stop, or change a medication without talking to the clinician who prescribes it.