Why Uncertainty Feels So Hard: Intolerance of Uncertainty and Anxiety

What is intolerance of uncertainty?

You send an important message and don't get a reply.

One person might think: `They'll respond when they can.`

Another person's mind may immediately begin: "Why haven't they replied? Did I say something wrong? Are they upset? Should I send another message? What if I've damaged the relationship?"

The unanswered message is the same. What differs is how difficult the uncertainty feels.

Psychologists use the term `intolerance of uncertainty`, often shortened to IU, to describe a tendency to react negatively to uncertain situations and to hold negative beliefs about what uncertainty means.

It does not mean that you literally cannot survive uncertainty. Everyone lives with uncertainty every day.

The issue is how strongly the mind feels compelled to resolve it.

Disliking uncertainty is normal

Most people prefer knowing what is going to happen.

We make plans, check the weather, read reviews, confirm appointments, and ask questions because information helps us make better decisions.

That is not a psychological problem.

Intolerance of uncertainty becomes more relevant when the need to know begins creating substantial distress or repeatedly changes behaviour.

For example, checking whether your flight is on time is sensible. Refreshing the airline app every two minutes despite having no new information may be serving a different purpose.

The question is not whether you seek certainty at all.

It is whether the search for certainty is helping you make a decision — or whether it has become the thing keeping the anxiety going.

Uncertainty is not the same as danger

An important distinction is easy to lose when you are anxious.

`I don't know` and `something bad is happening` are not the same statement.

If a medical test result has not arrived yet, you genuinely do not know the result. That uncertainty may be frightening, but the absence of information is not itself evidence of bad news.

If your manager says, "Let's talk tomorrow," you do not know what the conversation will contain. The uncertainty does not establish that the meeting will be negative.

The mind often dislikes leaving that space empty, so it fills the gap with a prediction.

When anxiety is high, that prediction is frequently the threatening one.

Why does not knowing feel so uncomfortable?

Uncertainty removes the ability to fully predict or control what happens next.

That can make it difficult to decide whether you need to prepare, protect yourself, take action, or simply wait.

For someone who struggles with uncertainty, the state of not knowing can therefore start feeling like a problem that urgently needs to be solved.

Research increasingly treats intolerance of uncertainty as a process that cuts across several forms of anxiety rather than belonging to only one diagnosis.

A 2026 preregistered meta-analysis by Akbari and colleagues synthesized 738 effect sizes from 115 studies and dissertations, representing 138 independent samples and 28,693 participants. Intolerance of uncertainty was strongly associated with worry and showed associations across generalized anxiety, social anxiety, PTSD, OCD, panic, and broader anxiety symptoms.

The relationship was strongest for generalized anxiety, which fits longstanding models of chronic worry, but it was clearly not limited to GAD.

Why worry can feel like preparation

Worry often feels active.

If you keep thinking about tomorrow's interview, perhaps you will notice something you have not prepared for.

If you replay the conversation enough times, perhaps you will finally understand what the other person meant.

If you imagine every possible thing that could go wrong, perhaps nothing will surprise you.

That makes worry easy to mistake for productive preparation.

Sometimes thinking really does reveal a useful next step.

But once you have extracted the useful information, continuing to think may be serving a different goal: trying to make the future feel certain.

A useful question is:

What do I know now that I didn't know ten minutes ago?

If the answer is nothing, more thinking may not be producing more information.

How uncertainty turns into overthinking

Many overthinking loops begin with a question that cannot be answered yet.

What if I made the wrong decision?

What if they don't like me?

What if I fail?

What if this feeling doesn't go away?

The mind then attempts to solve the uncertainty by generating more possibilities.

But each answer can create another question.

Our guide to how to stop overthinking explores repetitive negative thinking more broadly.

When uncertainty is the fuel, however, the important question is not always `How do I find the answer?`

It may be: `Is an answer actually available right now?`

How uncertainty fuels catastrophizing

When the future is unknown, the mind often gives extra attention to outcomes that would be costly or dangerous.

That can be useful to a point. Considering risk helps us prepare.

But uncertainty can also become catastrophizing when one possible negative outcome begins to feel like the most probable one.

Uncertainty: "I don't know how the presentation will go."

Catastrophe: "I'll freeze, everyone will think I'm incompetent, and this will damage my career."

The problem is not noticing that a bad outcome is possible.

It is allowing possibility to quietly become probability.

How uncertainty fuels mind reading

Social situations are filled with information you cannot directly access.

You cannot know exactly what another person thought about your comment, why they took several hours to reply, or what they noticed when you became nervous.

When uncertainty feels uncomfortable, the mind may try to resolve it by guessing.

Instead of: "I don't know what she thought," the conclusion becomes: "She thought I was awkward."

That is the mind reading cognitive distortion: an interpretation of someone else's private thoughts begins functioning as though it were established information.

Sometimes the difficult part is not generating a better interpretation.

It is accepting that you may not get access to the answer at all.

Why reassurance feels so compelling

When uncertainty creates anxiety, reassurance offers something powerful: temporary certainty.

You ask: "Do you think they're angry with me?"

Someone replies: "No, I'm sure they're just busy."

Your anxiety drops.

That relief can make reassurance feel like the solution.

But the underlying question may remain unresolved. You still do not actually know why the person has not replied.

Later, doubt can return and create the urge to ask again.

A 2023 daily-life study by Meyer and colleagues followed 104 young adults for 14 days. Intolerance of uncertainty was associated with greater reassurance seeking at baseline, and on days when participants experienced relatively higher anxiety, they also reported more reassurance-seeking behaviour.

This was an observational study and cannot establish that reassurance caused the anxiety. But it illustrates how closely the two behaviours can move together in daily life.

Reassurance seeking is not always unhealthy

This needs an important qualification.

Asking for reassurance is a normal part of human relationships.

You might reasonably ask your doctor whether a medication side effect is expected, ask your partner whether something you said upset them, or ask a colleague whether you understood an instruction correctly.

The issue is repetition and function.

Ask yourself:

• Am I seeking information I genuinely need?
• Has anything changed since the last time I asked?
• Would another answer actually help me make a decision?
• Or am I asking primarily so I can feel certain again for a few minutes?

Checking can serve the same purpose

Reassurance does not always come from another person.

It can come from checking.

You reread the email you already sent. Search the symptom again. Check whether somebody was recently online. Refresh the tracking page. Revisit your bank account. Review the conversation one more time.

Checking can be completely appropriate when new information may actually be available.

But repeated checking can also become an attempt to remove the feeling of uncertainty itself.

A 2026 study by Crawford and Purdon examined 204 university students with high levels of worry and found that intolerance of uncertainty uniquely predicted reassurance seeking as well as worry-related safety behaviours and avoidance.

That does not mean every checking behaviour is caused by intolerance of uncertainty. It supports the broader idea that the need to resolve uncertainty can influence what people do when they worry.

Problem solving vs certainty seeking

This is one of the most useful distinctions you can make.

Problem solving asks:

What can I do about this?

Certainty seeking asks:

How can I make sure nothing bad will happen?

The first question can produce an action.

The second often has no finish line.

For example:

• Problem solving: "I may miss the deadline. I can ask for the missing information today."
• Certainty seeking: "How can I guarantee the project will turn out perfectly?"
• Problem solving: "I don't understand this symptom. I can arrange an appropriate medical assessment."
• Certainty seeking: "How can I be 100% certain there is nothing medically wrong?"
• Problem solving: "I don't know if my friend is upset. If the distance continues, I can ask them."
• Certainty seeking: "Can I work out exactly what they think before they tell me?"

Three kinds of uncertainty

When you notice yourself looping around an unanswered question, it can help to sort it into one of three categories.

1. 1There is something useful I can do.
2. 2There is information I can reasonably obtain.
3. 3There is no reliable answer available yet.

1. There is something useful I can do

You are worried about tomorrow's presentation and realise you have not prepared the opening.

That uncertainty contains an actionable problem.

Prepare the opening.

Once you have taken the reasonable action, notice whether your mind immediately generates another requirement:

What if they ask a question I can't answer?

What if the technology fails?

What if I forget something?

At some point, preparation has done its job and uncertainty remains.

2. There is information you can reasonably obtain

Some uncertainty can be resolved through appropriate information gathering.

You can check the train time once. Ask what the meeting is about. Read the official instructions. Speak to a doctor about a symptom.

The important word is `reasonably`.

Information gathering becomes less useful when every answer creates a demand for stronger certainty.

One medical source becomes five. Five become twenty. A professional opinion becomes a search for confirmation that the professional cannot possibly be wrong.

More information is not always more certainty.

3. There is no reliable answer available yet

This is usually the hardest category.

You may genuinely have to wait.

You do not know whether you will get the job.

You do not know exactly what somebody thinks of you.

You do not know whether tomorrow will go according to plan.

You do not know whether the decision you made will turn out to have been the best possible one.

The work here is different.

There is no missing thought you need to discover.

There is uncertainty you need to carry.

Sometimes there is no answer yet

This sounds obvious when written down, but anxiety often operates as though every uncomfortable question must have an answer somewhere.

Perhaps if you replay the conversation differently.

Perhaps if you search for one more opinion.

Perhaps if you calculate the probability again.

But some information only arrives with time.

More thinking cannot manufacture it.

A useful response can simply be:

"I don't know yet, and there isn't anything else I need to do right now."

How to practise tolerating uncertainty

The aim is not to throw yourself into the most frightening uncertainty you can imagine.

It is to gradually practise making reasonable decisions without obtaining the maximum possible amount of certainty first.

1. 1Name the exact thing you do not know.
2. 2Decide whether action or information is genuinely available.
3. 3Choose what counts as enough information for this decision.
4. 4Notice the urge to check, analyse, or ask again.
5. 5Delay or reduce one unnecessary certainty-seeking behaviour when it is safe to do so.
6. 6Allow the unanswered question to remain unanswered for a while.
7. 7Continue with something that matters even though certainty has not arrived.

Step 1: Make the uncertainty specific

Instead of: "Everything feels uncertain," try to identify the actual unknown.

"I don't know whether they'll accept the proposal."

"I don't know why she hasn't replied."

"I don't know whether I'll feel anxious during the presentation."

A specific unknown is easier to evaluate than a general feeling that everything is unsafe.

Step 2: Decide what 'enough information' looks like

Many certainty-seeking loops have no stopping rule.

You keep researching until you feel certain.

The problem is that the feeling of certainty may never arrive.

Instead, choose the threshold before you begin.

For a purchase: "I'll compare three credible options, then decide."

For a work email: "I'll proofread it once, then send it."

For a routine decision: "I'll give myself ten minutes to decide rather than revisit it all evening."

The exact rule is less important than shifting the goal from `complete certainty` to `enough information to make a reasonable choice.`

Step 3: Notice reassurance without automatically obeying the urge

If you repeatedly ask for reassurance, removing it all at once may feel unnecessarily difficult.

Start smaller.

When the urge appears, ask: "Do I need information, or do I need the feeling of certainty?"

If you already have the information, experiment with waiting a little before asking again.

You are not trying to prove that the feared outcome will not happen.

You are learning that the feeling of uncertainty can rise and fall without always requiring an immediate response.

Step 4: Try a small uncertainty experiment

Uncertainty can be practised in ordinary, low-risk situations.

Leave a routine text without rereading it three times.

Choose from the menu without researching every option.

Send a low-stakes email after one careful proofread.

Allow somebody else to choose the film.

Wait before checking whether someone has replied.

These are essentially small behavioral experiments.

The prediction might be:

"If I don't check again, I'll feel anxious and won't be able to concentrate."

Then observe what actually happens.

The point is not to make yourself uncomfortable for its own sake. It is to gather evidence about whether uncertainty is as unmanageable as it feels.

Step 5: Act before certainty arrives

Many important decisions do not come with guarantees.

Starting a relationship, accepting a job, sharing an idea, travelling somewhere new, making a creative decision, and speaking honestly to someone all involve incomplete information.

If certainty becomes a prerequisite for action, life can gradually become smaller.

A more workable question is:

"Do I have enough information to take the next reasonable step?"

That is very different from:

"Can I guarantee this will turn out well?"

You do not need to think positively about uncertainty

Tolerance does not mean telling yourself that uncertainty is exciting or wonderful.

Sometimes uncertainty is deeply uncomfortable.

Waiting for medical results, navigating employment insecurity, dealing with a relationship problem, or facing financial instability can involve real consequences.

The goal is not to reframe genuine uncertainty into something pleasant.

It is to stop adding an impossible second requirement:

"I must know exactly how this will turn out before I can cope with it."

When uncertainty really does require action

Not every urge to reduce uncertainty is anxiety-driven.

There are situations where obtaining information or reducing risk is responsible.

Medical symptoms may require assessment. Financial commitments deserve due diligence. Safety risks should be investigated. Contracts should be read. Important instructions may need clarification.

Tolerance of uncertainty should never become an excuse to ignore information you genuinely need.

The difference is whether you are taking a proportionate action or pursuing a level of certainty the situation cannot provide.

How CBT works with intolerance of uncertainty

CBT approaches to uncertainty do not generally try to prove that everything will be okay.

Instead, treatment may help people distinguish productive from unproductive worry, identify beliefs about uncertainty, reduce safety behaviours, solve problems that genuinely can be solved, and gradually approach uncertain situations without excessive attempts to control the outcome.

A 2023 systematic review and meta-analysis by Wilson and colleagues examined 26 studies involving 1,199 adults with generalized anxiety disorder. Psychological treatments produced substantial reductions in intolerance of uncertainty as well as worry and anxiety.

CBT approaches that directly targeted intolerance of uncertainty produced larger reductions in uncertainty intolerance and worry immediately after treatment than more general CBT approaches, although that advantage was not maintained at follow-up.

That last point matters. It would be too strong to claim that explicitly targeting uncertainty has been proven superior over the long term.

What does the wider treatment research show?

There is encouraging evidence that intolerance of uncertainty can change, but the literature is not perfectly consistent.

A 2023 meta-analysis by Miller and McGuire examined 28 randomized controlled trials across anxiety-related conditions and found a large average improvement in intolerance of uncertainty compared with control conditions. Improvements in uncertainty intolerance also corresponded with improvements in anxiety symptoms.

However, a 2024 meta-analysis by Näsling and colleagues reached a more cautious conclusion. Across 22 studies and 1,491 participants, psychotherapy showed a large effect compared with passive controls, but effects were not significant when compared with active control conditions. The authors concluded that important questions remain about which treatment components actually produce change.

These findings are not necessarily contradictory. They highlight how much results depend on which studies, disorders, interventions, and comparison groups are included.

The safest conclusion is that intolerance of uncertainty is psychologically meaningful and can improve during treatment, while the exact mechanisms and most effective ways of targeting it continue to be studied.

What does the research say about intolerance of uncertainty overall?

The evidence that intolerance of uncertainty is associated with psychological distress is considerably stronger than the evidence for any one self-help technique.

A 2019 meta-analysis by McEvoy and colleagues synthesised 181 studies involving 52,402 participants and found a moderate overall association between intolerance of uncertainty and symptoms across several psychological disorders.

The newer 2026 preregistered meta-analysis substantially expanded the picture. Across 28,693 participants, intolerance of uncertainty was strongly related to worry and showed a hierarchy of associations across anxiety conditions: strongest for generalized anxiety and broader anxiety symptoms, followed by PTSD, social anxiety and OCD, with a smaller association for panic.

The authors' structural model also supported worry as one important pathway linking intolerance of uncertainty with anxiety.

These are associations, not proof that intolerance of uncertainty single-handedly causes anxiety disorders.

They do suggest that how we respond to not knowing is an important piece of the anxiety puzzle.

How Reframer helps with uncertainty

Many thoughts entered into Reframer contain a question that cannot be completely answered.

"Did I make the wrong decision?"

"What if tomorrow goes badly?"

"Why hasn't she replied?"

"What does he really think of me?"

Rather than automatically trying to reassure you, Reframer can help separate three things: what you know, what you are predicting, and what you can actually do.

If the prediction goes beyond the evidence, cognitive reframing may help.

If there is a genuine problem, the useful response may be a concrete next step.

If the thought has become repetitive without producing anything new, recognising the rumination loop may matter more.

And sometimes the most accurate answer is simply:

"There isn't enough information to know this yet."

Sometimes you need an answer. Sometimes you need a plan. Sometimes you need to not know yet.

Uncertainty is uncomfortable partly because the mind treats the discomfort as unfinished business.

Something must still need solving.

Sometimes that is true.

There is a question to ask, information to gather, a conversation to have, or a practical step to take.

But there are also moments when you have reached the edge of the information available.

Another hour of thinking cannot tell you what someone else will decide tomorrow.

Another reassurance cannot guarantee how you will feel next week.

Another search cannot remove every possible risk.

The goal is not complete comfort with uncertainty.

It is learning that you can still choose what to do next while some questions remain unanswered.