An intrusive thought is an unwanted thought, image or urge that pops into your mind uninvited. It might be a flash of pushing someone off a platform, a sudden doubt about whether you locked the door, an image of something terrible happening to someone you love, or a thought that feels completely at odds with who you are. For most people, these thoughts pass quickly. For some, they stick, return again and again, and become a source of real distress.
This article explains why intrusive thoughts happen, why some of them become a problem, and how CBT can help.
Intrusive thoughts are normal
The first thing to know is that intrusive thoughts are a normal part of how the human mind works. Studies across many countries have found that more than nine in ten people report having unwanted intrusive thoughts. They often include thoughts about harm, sex, illness, embarrassment or doing something out of character, which are exactly the kinds of thoughts people tend to assume nobody else has.
The mind generates a constant stream of ideas, many of them random, strange or unpleasant. Most of the time, we barely notice them. Having a disturbing thought says very little about who you are or what you want.
Why some intrusive thoughts get stuck
If almost everyone has intrusive thoughts, why do they become a problem for some people? The answer lies less in the thought itself and more in what happens next.
When a thought is interpreted as meaningful or dangerous ("Why would I think that? What if it means something? What if I act on it?"), it triggers anxiety. Anxiety makes the mind pay closer attention to the thought, which makes it seem more frequent and more important, which creates more anxiety. Some common beliefs make this much more likely:
- That having a thought makes it more likely to happen
- That thinking something bad is almost as bad as doing it
- That you are responsible for preventing anything bad that might follow from a thought
- That you should be able to control your thoughts
Intrusive thoughts and anxiety
Intrusive thoughts become more frequent and harder to dismiss when you are anxious, stressed or exhausted. They are a common feature of several anxiety problems: sudden thoughts of illness in health anxiety, catastrophic "what ifs" in generalised anxiety, or vivid images of embarrassment in social anxiety. In these cases, the thoughts are part of a wider pattern of anxiety, and treating the anxiety usually reduces them. You can read more about CBT for anxiety in London and online.
Intrusive thoughts and OCD
Intrusive thoughts become part of OCD when they set off compulsions: things you do, physically or mentally, to neutralise the thought, check that it isn't true, or prevent what you fear. Common themes include:
- Unwanted thoughts or images of causing harm (harm OCD)
- Unwanted sexual thoughts about children (POCD)
- Persistent doubts about a relationship (relationship OCD, or ROCD)
- Doubts about your sexual orientation (sometimes called HOCD)
- Fears of contamination, or of having made a terrible mistake
In OCD, the thoughts that stick are usually the ones that go most against a person's values. That is why they are so distressing, and why they so rarely reflect any real wish or risk. Where most of the compulsions happen in your head, the OCD can be hard to recognise: see Pure O: when compulsions aren't visible. For how OCD is treated, see OCD therapy with ERP in London and online.
What keeps intrusive thoughts going
The natural responses to a distressing thought are to push it away, check that it isn't true, or avoid whatever triggers it. These all make sense. Unfortunately, they all tend to make intrusive thoughts more frequent and more powerful.
Thought suppression
Trying not to think about something makes you think about it more. In a well-known experiment, people asked not to think about a white bear ended up thinking about it more than people who were free to think about anything. The same happens with intrusive thoughts. Every attempt to push the thought away is also a reminder of it, and the thought tends to rebound.
Reassurance
Asking others whether something is okay, searching online, or going over the arguments in your own head can bring relief. But the relief is short-lived, and each time you seek reassurance, you teach yourself that the thought was dangerous enough to need it. I explain this in Why reassurance keeps OCD going.
Avoidance
Steering clear of the people, places or objects that trigger the thought, such as knives, driving or being alone with a child, reduces anxiety in the moment. It also stops you from discovering that you can be in those situations safely, and life gradually gets smaller.
Intolerance of uncertainty
Underneath many of these responses is the need to be completely sure: that the thought doesn't mean anything, that nothing bad will happen, that you would never act on it. That kind of certainty isn't available, and the search for it keeps the cycle running. See OCD and intolerance of uncertainty.
How CBT can help
CBT doesn't try to stop intrusive thoughts. That isn't possible, and as the white bear shows, trying makes things worse. Instead, it changes your relationship with them, so that they lose their power and become what they are for most people: passing mental events.
Treatment starts with understanding your particular pattern: the thoughts, the meaning you attach to them, and everything you do in response, including the less obvious mental responses. It then works on the beliefs that make the thoughts feel dangerous, and gradually reduces suppression, reassurance and avoidance. Where the thoughts are part of OCD, the most effective approach is exposure and response prevention (ERP). See How ERP therapy for OCD works.
Working with someone matters here, because the responses that keep intrusive thoughts going are often the hardest to see from the inside. People are often surprised by how much changes once intrusive thoughts are understood rather than fought. The goal is not to have no unpleasant thoughts. It is to reach a point where they no longer run the show.
When to seek therapy
It may be worth speaking to a therapist if:
- Intrusive thoughts take up a significant part of your day
- They cause you a lot of distress, guilt or shame
- You are avoiding people, places or activities because of them
- You find yourself checking, seeking reassurance or mentally reviewing to cope
- They are affecting your work, your relationships or your sense of who you are
Many people put off getting help for years, often because they are ashamed of what their thoughts are about, or because they assume what they are experiencing doesn't count. It does.
The thoughts described in this article are unwanted and distressing to the person having them. If you are having thoughts of harming yourself, or thoughts of harming others that don't feel unwanted, that is different: please speak to your GP, call Samaritans on 116 123, or call 999 in an emergency.
In my practice
Intrusive thoughts are one of the most common reasons people get in touch with me, whether as part of OCD or anxiety. Many tell me they have never said their thoughts aloud before. Being able to describe them to someone who recognises exactly what they are, and isn't alarmed by them, is often the first real relief. From there, treatment is structured and practical. You can read more about how I work on my pages about OCD therapy with ERP and CBT for anxiety, in London and online.
If intrusive thoughts are affecting your work, your relationships, or your sense of who you are, it may be worth speaking to someone. I offer an initial assessment, online or in person in Queen's Park, to explore whether therapy is the right step.
Book a free consultation
BABCP-accredited CBT therapist and EMDR Europe accredited practitioner, in clinical practice since 2015. Guy works with adults online and in Queen's Park, North West London, with a particular focus on OCD, anxiety and trauma. More about Guy
