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What Are Intrusive Thoughts, And Should You Worry About Them?

It's actually perfectly normal to randomly think about driving off a cliff sometimes. No, seriously. It is.


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer

Collage with a woman covering her face and screaming mouths

Intrusive thoughts can be hard to ignore, but they're not usually a sign that anything is wrong. Image Credit: SvetaZi/

At some point fairly recently, we’re going to guess you found yourself accidentally imagining a complete stranger in the buff. Did we miss the mark? How about unexpectedly obsessing over whether you left your front door unlocked? Perhaps you even convinced yourself there’d be an intruder waiting for you when you got home. Maybe a naked intruder. Don’t worry, we’ve not been reading your diary – we’re just playing the odds. Those are all very common intrusive thoughts, with most of us experiencing at least one of them.

Maybe that surprises you. After all, we don’t usually talk about those random taboo thoughts and impulses that occasionally pop into our heads – perhaps we’re all too worried about everyone else thinking that we’re crazy or dangerous. 


But in fact, intrusive thoughts are an extremely normal part of everyday life, with a slew of techniques to manage them. And honestly? It turns out it’s those who never experience them that are the real weirdos.

What are intrusive thoughts?

Unlike some of the jargon that can pervade the arena of psychology, intrusive thoughts are exactly what they sound like: they’re thoughts that are intrusive.

You might think that doesn’t narrow things down much, and you’d be right. In a general sense, though, that’s really all they are: any random thought that “pops into mind”, clinical psychologist Professor Mark Freeston, who specializes in obsessive-compulsive disorder (OCD) and anxiety disorders at Newcastle University, told BBC Science Focus.

Technically, that can include positive thoughts as well as negative ones – but it’s the nasty ones that tend to affect us more. Those might be things like looking over the barrier on the Grand Canyon Skywalk and idly thinking that maybe you should just jump right off and see what happens, or seeing the face of a loved one and randomly imagining punching them right in the nose; it could be a fleeting, panicked thought about picking up a disease or contamination. Sometimes it’s as simple as a minor freak-out about how others are seeing you – did I forget to put on make-up this morning? Are my flies undone? Do I look as nervous as I feel?


For psychologists, the mark of an intrusive thought, as opposed to normal worries or thoughts, is that they are egodystonic. Simply put, that means they run counter to what you generally believe to be true – that’s why “what if I just stabbed that adorable kitten in the face” is an intrusive thought, while “ohmygosh I just want to squeeze him to death!” is just a normal reaction.

“A lot of times when patients bring it up to me, they might preface it with something like, ‘I’m not crazy, but this weird thought comes into my mind,’” confirmed Dr Kerry-Ann Williams, a lecturer in psychiatry at Harvard Medical School, to Harvard Health Publishing back in 2021. “They might think about hurting a family member, such as a baby. When the thought happens, they’re horrified – ‘I can’t even believe that came into my mind. I shouldn’t tell anyone; they might think something is wrong with me.’”

Are intrusive thoughts normal?

Given how shocking it can be to suddenly find yourself fighting a minor urge to get naked in front of your boss, you may well assume that intrusive thoughts are a sign that you’re a bit, well, odd. In fact, nothing could be further from the truth.

“We know that people are more likely to notice them or struggle with them during stressful periods,” Adam Radomsky, Professor of Psychology at Concordia University, told Science Focus. “But I think it’s just a fact of humanity that we have them. Most of them we probably don’t notice.”


When we say they’re common, we’re not kidding: studies into the phenomenon have found that almost 80 percent of us – that’s four out of every five people – have experienced intrusive thoughts at some point. And that’s the lower bound. A more recent study from 2014 upped that figure to a whopping 94 percent of people, consistent in 777 participants across six continents.

The most common type of intrusive thought? Those nagging doubts about whether you’re doing a task correctly, according to the 2014 study. However, they come in all different types: a 1993 survey of 293 people without diagnosed mental health conditions totted up more than 50 genres of common intrusive thoughts, and all of them were experienced by at least one in 20 respondents.

Why do we get intrusive thoughts?

For the most part, the causes of intrusive thoughts are as innocuous and normal as we now know the thoughts themselves are. 

“Intrusive thoughts may not have a cause. They can just happen randomly,” explains Healthline. “Some thoughts wander into your brain. Then just as quickly, they exit, leaving no lasting impression.”


That’s not really surprising. If we’re basically all wandering around with these weird ideas popping into our heads at random intervals, then it kind of has to be normal by definition, right? However, in some rare cases, intrusive thoughts can be a symptom of something more serious.

Some of those causes might be a mental health condition – particularly conditions like social anxiety, OCD, or post-traumatic stress disorder (PTSD). “In social anxiety, the intrusive thoughts would likely be ‘How are other people seeing me?’, ‘Is my hand shaking?’” Freeston told Science Focus; for those with OCD, they might find themselves thinking about germs or contamination, he explained, while for people with PTSD, intrusive thoughts might take the form of flashbacks or memories of traumatic events.

Occasionally, intrusive thoughts can be caused by physical problems too. Brain injuries, Parkinson’s disease, and dementia are all associated with intrusive thoughts – so, while they’re not anything to worry about per se, if you’ve noticed a recent change to your thought patterns, or your intrusive thoughts are becoming more distressing or harder to shake off, it’s probably a good idea to speak to a doctor.

However, even if your intrusive thoughts are triggered by some mental upset, don’t worry too much. “Any life stressor, if big enough, can increase your risk of having intrusive thoughts,” Williams told Harvard Health. “Keep in mind that you might not need help forever. It may be a very short-term thing.”

How to deal with intrusive thoughts

As with most mental health issues, the key to whether intrusive thoughts are a problem is how badly they affect you. In other words: just because you’re having intrusive thoughts, doesn’t necessarily mean you ought to feel the need to do anything about them.

So, for instance, “someone could have a thought about some bizarre, evil thing happening,” Freeston said. “If you were Stephen King you’d say, ‘That’s a great idea.’ And then write a novel. But if you think, ‘What sort of a person has this bizarre thought?’ or ‘It might mean that I’m this awful person that I think I am’, from there, an intrusive thought could become an obsession.”

Luckily, if your intrusive thoughts are causing issues in your life, there are some well-established and science-backed techniques for dealing with them. Cognitive behavioral therapy (CBT) is a particular favorite for those whose intrusive thoughts are linked to OCD or PTSD – it’s a treatment that aims to help change the way you think, retraining our brains to respond more reasonably to the thoughts which are stressing us out.

Other thoughts might be better treated by a technique known as exposure and response therapy. Not for the faint-hearted, this involves purposefully exposing yourself to the object of your fear. So, if your intrusive thoughts revolve around germs and contamination, for example, you might be challenged to do something like shake someone’s hand without administering hand sanitizer afterward.


As scary as that may sound, it’s important to realize that intrusive thoughts usually respond well to therapy – and in many cases, they don’t hang around long-term. Remember: they might be disturbing or annoying, but they’re also normal, and not a reflection of you as a person.

“Think to yourself, ‘that’s just an intrusive thought; it’s not how I think, it’s not what I believe, and it’s not what I want to do,’” Williams said.

“Don’t try to make it go away,” she advised. “The more you think about it, the more anxious you get and the worse the thoughts get.”

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions. 


 All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current. 


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