Intolerance of Uncertainty: Why Not Knowing Can Feel So Hard

Quick Answer

Intolerance of uncertainty refers to difficulty tolerating the discomfort of not knowing what will happen. For some people, uncertainty itself begins to feel threatening, even when there is no clear evidence that something bad will happen.

In response, they may worry, seek reassurance, overprepare, check, research, avoid, or mentally replay situations in an attempt to feel more certain.

The problem is that certainty is rarely permanent.

Therapy can help clients change their relationship with uncertainty rather than continually trying to eliminate it.

Who This Article Is For

This article is written primarily for therapists, psychologists, counselors, and other mental health professionals working with clients who struggle with anxiety, chronic worry, reassurance seeking, checking, avoidance, or a persistent need to know what will happen next.

It may be particularly helpful when working with generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), health anxiety, and other anxiety-related presentations.

Why It Matters

Many clients come to therapy wanting help with anxiety.

But underneath the anxiety, I often find a quieter question:

"How can I know for sure that everything is going to be okay?"

The answer, of course, is that we can't.

We can't know with complete certainty that a relationship will work out, that a medical test will be normal, that we made the right decision, or that something difficult won't happen.

Most people don't particularly enjoy uncertainty. The clinical issue is not simply disliking the unknown. It is what happens when someone begins organizing their life around trying to eliminate it.

That's when worry, checking, reassurance seeking, avoidance, and other safety behaviors can begin to take over.

What Is Intolerance of Uncertainty?

Intolerance of uncertainty refers to a tendency to respond negatively to uncertain situations or events.

A person with high intolerance of uncertainty may experience the possibility of a negative outcome as difficult to tolerate, even when that outcome is unlikely.

Consider the difference between:

"I don't know what will happen, and I don't like that."

and:

"I don't know what will happen, and I need to figure it out before I can feel okay."

That second response can create an exhausting search for certainty.

The difficulty is that anxiety is remarkably good at finding the next question.

What Intolerance of Uncertainty Can Look Like

Intolerance of uncertainty does not always look like obvious anxiety.

It may look like:

• Repeatedly asking other people what they think

• Googling symptoms or possible outcomes

• Over-researching decisions

• Making extensive contingency plans

• Checking and rechecking work

• Replaying conversations

• Avoiding decisions until certainty feels possible

• Asking the same question in slightly different ways

• Mentally reviewing whether something was done correctly

• Preparing excessively for situations that cannot be fully controlled

A client may believe the goal of these behaviors is to solve the problem.

Sometimes it is.

But sometimes the real goal is to make the uncomfortable feeling of uncertainty go away.

That distinction matters.

What Does the Research Say?

Intolerance of uncertainty has been studied extensively in relation to generalized anxiety disorder and chronic worry, although research increasingly suggests that it is relevant across a range of anxiety-related difficulties.

The original intolerance-of-uncertainty model of GAD proposed that difficulty tolerating uncertainty contributes to excessive worry. When uncertainty is interpreted as threatening, worry may become an attempt to anticipate every possible outcome and feel more prepared.

More recent treatment research has examined behavioral experiments specifically designed to help individuals test their beliefs about uncertainty. Rather than trying to convince someone that an uncertain situation will turn out well, these approaches help clients experience uncertainty directly and discover what happens when they stop trying to control it.

The therapeutic goal is therefore not certainty.

It is greater flexibility in the presence of uncertainty.

Examples of Intolerance of Uncertainty

Health Anxiety

A client notices an unfamiliar sensation.

They search online, ask their partner what they think, check the symptom repeatedly, and eventually schedule a medical appointment.

The doctor provides reassurance.

For a while, they feel better.

Then another sensation appears.

The question becomes:

"But how do I know this one is okay?"

Relationships

A client notices that their partner seems quieter than usual.

They begin reviewing recent conversations.

"Did I say something wrong?"

"Are they upset?"

"Is something changing?"

They may repeatedly ask whether everything is okay.

The reassurance helps—but only until the next ambiguous interaction.

Decision-Making

A client spends hours researching a relatively ordinary decision because choosing one option means giving up the certainty that another choice might have been better.

The goal quietly shifts from making a reasonable decision to making a decision they will never regret.

That's an impossible standard.

Generalized Worry

A client worries about their children, finances, health, work, and the future.

Each worry feels different.

But underneath them may be the same difficulty:

"I don't know what is going to happen, and I don't trust myself to handle it if something goes wrong."

That is often an important therapeutic shift.

We may not need to solve every individual worry.

We may need to work on the client's relationship with not knowing.

How Therapists Can Help

1. Identify the Search for Certainty

When a client brings a worry into session, it can be tempting to focus immediately on the content.

Instead, become curious about the process.

Ask:

• What are you hoping to know for certain?

• How certain would you need to feel before you could let this go?

• What do you do when uncertainty shows up?

• How long does the relief from those behaviors usually last?

These questions can reveal whether the problem is the situation itself or the client's struggle to resolve uncertainty.

2. Distinguish Problem-Solving From Worry

Some uncertain situations require action.

Others do not.

A useful question is:

"Is there a problem we can solve right now?"

If yes, problem-solving may be appropriate.

If not, continued mental effort may simply be another attempt to manufacture certainty.

3. Identify Safety Behaviors

Reassurance seeking, checking, researching, avoidance, and overpreparation can all function as attempts to reduce uncertainty.

The goal is not to label every cautious behavior as pathological.

Instead, look at function.

What does the client believe this behavior is doing for them?

What do they fear would happen if they didn't do it?

4. Use Behavioral Experiments

Rather than telling clients they can tolerate uncertainty, help them discover it.

A behavioral experiment might involve:

• Sending a text without rereading it five times

• Making a small decision without additional research

• Allowing an email response to remain unknown

• Asking a question without mentally rehearsing it first

• Leaving a minor task "good enough"

• Resisting the urge to seek reassurance

Before the experiment, identify the prediction.

"If I don't check, what do you expect will happen?"

Afterward, review what the client learned.

The goal is not necessarily to discover that nothing bad happens.

Sometimes uncomfortable things do happen.

The more durable learning is often:

"I can handle not knowing."

5. Build Confidence Rather Than Certainty

Anxiety often asks therapists to join the client's search for reassurance.

"Do you think I'll be okay?"

"Do you think I made the right choice?"

"Do you think this symptom is serious?"

We can empathize without pretending to know what we cannot know.

Instead of helping clients become more certain about the future, therapy can help them become more confident in their ability to respond to whatever happens.

Common Therapist Pitfalls

Providing Too Much Reassurance

Reassurance can be compassionate and appropriate. But when it becomes the primary way a client regulates uncertainty, therapy can accidentally become part of the anxiety cycle.

Turning Uncertainty Into Positive Thinking

The goal is not to replace:

"Something bad might happen."

with:

"Everything will definitely be fine."

Both statements attempt to predict the future.

A more flexible position is:

"I don't know exactly what will happen, and I can respond when I know more."

Making Every Uncertain Situation an Exposure

Not every concern is anxiety. Sometimes clients need information, planning, medical care, advocacy, or practical problem-solving.

Clinical judgment matters.

Moving Too Quickly

Taking away reassurance or safety behaviors without helping a client understand their function can feel invalidating rather than therapeutic.

Curiosity usually gets us further than simply telling someone to stop.

Putting It Into Practice

A simple framework for working with uncertainty is:

NOTICE

N - Name the uncertainty
What don't I know?

O - Observe the urge
What do I want to do to make myself feel certain?

T - Test the function
Am I solving a problem or trying to get rid of uncertainty?

I - Identify the prediction
What am I afraid will happen if I don't act?

C- Choose an experiment
What small amount of uncertainty could I allow?

E - Examine the learning
What did I discover about uncertainty—and about my ability to cope?

FAQ

Is intolerance of uncertainty the same as anxiety?

No. Most people experience uncertainty as uncomfortable at times. Intolerance of uncertainty refers more specifically to how someone responds to not knowing and the extent to which they believe uncertainty is unacceptable, dangerous, or impossible to manage.

Is intolerance of uncertainty only associated with GAD?

No. Although IU has been studied extensively in generalized anxiety disorder, research has linked it with multiple forms of anxiety and related difficulties.

Should therapists encourage clients to accept all uncertainty?

No. Some situations call for information gathering, planning, or action. The clinical task is helping clients distinguish useful problem-solving from repetitive attempts to achieve impossible certainty.

How is intolerance of uncertainty related to reassurance seeking?

Reassurance seeking can function as one strategy for reducing uncertainty. The reassurance may provide temporary relief, but repeated reassurance can reinforce the belief that uncertainty cannot be tolerated without outside confirmation.

Can behavioral experiments help?

Yes. Behavioral experiments can help clients test beliefs about uncertainty in everyday situations and learn through direct experience rather than reassurance alone.

Key Takeaways

• Intolerance of uncertainty is not simply disliking the unknown.

• The search for certainty can show up as worry, checking, reassurance seeking, avoidance, research, and overpreparation.

• These strategies often provide temporary relief while making future uncertainty harder to tolerate.

• Therapy can help clients distinguish genuine problem-solving from attempts to eliminate uncertainty.

• Behavioral experiments allow clients to discover what happens when they respond differently.

• The goal is not to convince clients that everything will be okay.

• The goal is to build greater confidence in their ability to cope with not knowing.

From Clinical Practice

One thing I've noticed over the years is how often clients initially believe that if they could just get the right answer, their anxiety would finally settle down.

And sometimes an answer does help.

But with anxiety, there is often another question waiting behind it.

When I notice that happening, I become less interested in answering each individual "what if" and more curious about what the client believes they need from certainty.

Often, underneath the search for an answer is something more vulnerable:

"If I don't know what's going to happen, I don't know if I'll be able to handle it."

That gives us somewhere different to work.

Instead of spending therapy trying to predict the future together, we can begin helping the client trust their ability to meet the future when it arrives.

Clinical Pearls

Look for the question underneath the question. A client may be asking for information when what they really want is certainty.

Follow the relief. If a behavior repeatedly produces immediate relief but the same fear keeps returning, explore whether it is maintaining the cycle.

Don't confuse uncertainty with danger. They are not the same thing, although anxiety often treats them as if they are.

Confidence is more durable than reassurance. We cannot promise clients that difficult things won't happen. We can help them discover that they are more capable of responding than anxiety tells them.

Keep the experiments small enough to create learning. The goal is not to overwhelm clients. It is to give them repeated opportunities to experience uncertainty without automatically trying to eliminate it.

Reflection Question

Think about a client who repeatedly brings new worries into therapy.

Are you helping them solve genuinely different problems—or could you both be working on different versions of the same underlying problem: the difficulty of not knowing?

Further Reading

For therapists interested in exploring this topic further, look for work by Michel Dugas and colleagues on the intolerance-of-uncertainty model of generalized anxiety disorder and behavioral experiments targeting beliefs about uncertainty.

Related Therapist Marketplace articles:

Why Reassurance Makes Anxiety Worse (And What Therapists Can Do Instead)

What Are Safety Behaviors? Examples, CBT Strategies & Therapy Guide

References

Buhr, K., & Dugas, M. J. (2002). The intolerance of uncertainty scale: Psychometric properties of the English version. Behaviour Research and Therapy, 40(8), 931–945.

Carleton, R. N. (2016). Into the unknown: A review and synthesis of contemporary models involving uncertainty. Journal of Anxiety Disorders, 39, 30–43.

Dugas, M. J., Gagnon, F., Ladouceur, R., & Freeston, M. H. (1998). Generalized anxiety disorder: A preliminary test of a conceptual model. Behaviour Research and Therapy, 36(2), 215–226.

Hebert, E. A., Dugas, M. J., Tulloch, T. G., & Holowka, D. W. (2022). Behavioral experiments for intolerance of uncertainty: A randomized clinical trial for adults with generalized anxiety disorder. Behavior Therapy.

McEvoy, P. M., & Mahoney, A. E. J. (2012). To be sure, to be sure: Intolerance of uncertainty mediates symptoms of various anxiety disorders and depression. Behavior Therapy, 43(3), 533–545.

Quick Answer

Intolerance of uncertainty refers to difficulty tolerating the discomfort of not knowing what will happen. For some people, uncertainty itself begins to feel threatening, even when there is no clear evidence that something bad will happen.

In response, they may worry, seek reassurance, overprepare, check, research, avoid, or mentally replay situations in an attempt to feel more certain.

The problem is that certainty is rarely permanent.

Therapy can help clients change their relationship with uncertainty rather than continually trying to eliminate it.

Who This Article Is For

This article is written primarily for therapists, psychologists, counselors, and other mental health professionals working with clients who struggle with anxiety, chronic worry, reassurance seeking, checking, avoidance, or a persistent need to know what will happen next.

It may be particularly helpful when working with generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), health anxiety, and other anxiety-related presentations.

Why It Matters

Many clients come to therapy wanting help with anxiety.

But underneath the anxiety, I often find a quieter question:

"How can I know for sure that everything is going to be okay?"

The answer, of course, is that we can't.

We can't know with complete certainty that a relationship will work out, that a medical test will be normal, that we made the right decision, or that something difficult won't happen.

Most people don't particularly enjoy uncertainty. The clinical issue is not simply disliking the unknown. It is what happens when someone begins organizing their life around trying to eliminate it.

That's when worry, checking, reassurance seeking, avoidance, and other safety behaviors can begin to take over.

What Is Intolerance of Uncertainty?

Intolerance of uncertainty refers to a tendency to respond negatively to uncertain situations or events.

A person with high intolerance of uncertainty may experience the possibility of a negative outcome as difficult to tolerate, even when that outcome is unlikely.

Consider the difference between:

"I don't know what will happen, and I don't like that."

and:

"I don't know what will happen, and I need to figure it out before I can feel okay."

That second response can create an exhausting search for certainty.

The difficulty is that anxiety is remarkably good at finding the next question.

What Intolerance of Uncertainty Can Look Like

Intolerance of uncertainty does not always look like obvious anxiety.

It may look like:

• Repeatedly asking other people what they think

• Googling symptoms or possible outcomes

• Over-researching decisions

• Making extensive contingency plans

• Checking and rechecking work

• Replaying conversations

• Avoiding decisions until certainty feels possible

• Asking the same question in slightly different ways

• Mentally reviewing whether something was done correctly

• Preparing excessively for situations that cannot be fully controlled

A client may believe the goal of these behaviors is to solve the problem.

Sometimes it is.

But sometimes the real goal is to make the uncomfortable feeling of uncertainty go away.

That distinction matters.

What Does the Research Say?

Intolerance of uncertainty has been studied extensively in relation to generalized anxiety disorder and chronic worry, although research increasingly suggests that it is relevant across a range of anxiety-related difficulties.

The original intolerance-of-uncertainty model of GAD proposed that difficulty tolerating uncertainty contributes to excessive worry. When uncertainty is interpreted as threatening, worry may become an attempt to anticipate every possible outcome and feel more prepared.

More recent treatment research has examined behavioral experiments specifically designed to help individuals test their beliefs about uncertainty. Rather than trying to convince someone that an uncertain situation will turn out well, these approaches help clients experience uncertainty directly and discover what happens when they stop trying to control it.

The therapeutic goal is therefore not certainty.

It is greater flexibility in the presence of uncertainty.

Examples of Intolerance of Uncertainty

Health Anxiety

A client notices an unfamiliar sensation.

They search online, ask their partner what they think, check the symptom repeatedly, and eventually schedule a medical appointment.

The doctor provides reassurance.

For a while, they feel better.

Then another sensation appears.

The question becomes:

"But how do I know this one is okay?"

Relationships

A client notices that their partner seems quieter than usual.

They begin reviewing recent conversations.

"Did I say something wrong?"

"Are they upset?"

"Is something changing?"

They may repeatedly ask whether everything is okay.

The reassurance helps—but only until the next ambiguous interaction.

Decision-Making

A client spends hours researching a relatively ordinary decision because choosing one option means giving up the certainty that another choice might have been better.

The goal quietly shifts from making a reasonable decision to making a decision they will never regret.

That's an impossible standard.

Generalized Worry

A client worries about their children, finances, health, work, and the future.

Each worry feels different.

But underneath them may be the same difficulty:

"I don't know what is going to happen, and I don't trust myself to handle it if something goes wrong."

That is often an important therapeutic shift.

We may not need to solve every individual worry.

We may need to work on the client's relationship with not knowing.

How Therapists Can Help

1. Identify the Search for Certainty

When a client brings a worry into session, it can be tempting to focus immediately on the content.

Instead, become curious about the process.

Ask:

• What are you hoping to know for certain?

• How certain would you need to feel before you could let this go?

• What do you do when uncertainty shows up?

• How long does the relief from those behaviors usually last?

These questions can reveal whether the problem is the situation itself or the client's struggle to resolve uncertainty.

2. Distinguish Problem-Solving From Worry

Some uncertain situations require action.

Others do not.

A useful question is:

"Is there a problem we can solve right now?"

If yes, problem-solving may be appropriate.

If not, continued mental effort may simply be another attempt to manufacture certainty.

3. Identify Safety Behaviors

Reassurance seeking, checking, researching, avoidance, and overpreparation can all function as attempts to reduce uncertainty.

The goal is not to label every cautious behavior as pathological.

Instead, look at function.

What does the client believe this behavior is doing for them?

What do they fear would happen if they didn't do it?

4. Use Behavioral Experiments

Rather than telling clients they can tolerate uncertainty, help them discover it.

A behavioral experiment might involve:

• Sending a text without rereading it five times

• Making a small decision without additional research

• Allowing an email response to remain unknown

• Asking a question without mentally rehearsing it first

• Leaving a minor task "good enough"

• Resisting the urge to seek reassurance

Before the experiment, identify the prediction.

"If I don't check, what do you expect will happen?"

Afterward, review what the client learned.

The goal is not necessarily to discover that nothing bad happens.

Sometimes uncomfortable things do happen.

The more durable learning is often:

"I can handle not knowing."

5. Build Confidence Rather Than Certainty

Anxiety often asks therapists to join the client's search for reassurance.

"Do you think I'll be okay?"

"Do you think I made the right choice?"

"Do you think this symptom is serious?"

We can empathize without pretending to know what we cannot know.

Instead of helping clients become more certain about the future, therapy can help them become more confident in their ability to respond to whatever happens.

Common Therapist Pitfalls

Providing Too Much Reassurance

Reassurance can be compassionate and appropriate. But when it becomes the primary way a client regulates uncertainty, therapy can accidentally become part of the anxiety cycle.

Turning Uncertainty Into Positive Thinking

The goal is not to replace:

"Something bad might happen."

with:

"Everything will definitely be fine."

Both statements attempt to predict the future.

A more flexible position is:

"I don't know exactly what will happen, and I can respond when I know more."

Making Every Uncertain Situation an Exposure

Not every concern is anxiety. Sometimes clients need information, planning, medical care, advocacy, or practical problem-solving.

Clinical judgment matters.

Moving Too Quickly

Taking away reassurance or safety behaviors without helping a client understand their function can feel invalidating rather than therapeutic.

Curiosity usually gets us further than simply telling someone to stop.

Putting It Into Practice

A simple framework for working with uncertainty is:

NOTICE

N - Name the uncertainty
What don't I know?

O - Observe the urge
What do I want to do to make myself feel certain?

T - Test the function
Am I solving a problem or trying to get rid of uncertainty?

I - Identify the prediction
What am I afraid will happen if I don't act?

C- Choose an experiment
What small amount of uncertainty could I allow?

E - Examine the learning
What did I discover about uncertainty—and about my ability to cope?

FAQ

Is intolerance of uncertainty the same as anxiety?

No. Most people experience uncertainty as uncomfortable at times. Intolerance of uncertainty refers more specifically to how someone responds to not knowing and the extent to which they believe uncertainty is unacceptable, dangerous, or impossible to manage.

Is intolerance of uncertainty only associated with GAD?

No. Although IU has been studied extensively in generalized anxiety disorder, research has linked it with multiple forms of anxiety and related difficulties.

Should therapists encourage clients to accept all uncertainty?

No. Some situations call for information gathering, planning, or action. The clinical task is helping clients distinguish useful problem-solving from repetitive attempts to achieve impossible certainty.

How is intolerance of uncertainty related to reassurance seeking?

Reassurance seeking can function as one strategy for reducing uncertainty. The reassurance may provide temporary relief, but repeated reassurance can reinforce the belief that uncertainty cannot be tolerated without outside confirmation.

Can behavioral experiments help?

Yes. Behavioral experiments can help clients test beliefs about uncertainty in everyday situations and learn through direct experience rather than reassurance alone.

Key Takeaways

• Intolerance of uncertainty is not simply disliking the unknown.

• The search for certainty can show up as worry, checking, reassurance seeking, avoidance, research, and overpreparation.

• These strategies often provide temporary relief while making future uncertainty harder to tolerate.

• Therapy can help clients distinguish genuine problem-solving from attempts to eliminate uncertainty.

• Behavioral experiments allow clients to discover what happens when they respond differently.

• The goal is not to convince clients that everything will be okay.

• The goal is to build greater confidence in their ability to cope with not knowing.

From Clinical Practice

One thing I've noticed over the years is how often clients initially believe that if they could just get the right answer, their anxiety would finally settle down.

And sometimes an answer does help.

But with anxiety, there is often another question waiting behind it.

When I notice that happening, I become less interested in answering each individual "what if" and more curious about what the client believes they need from certainty.

Often, underneath the search for an answer is something more vulnerable:

"If I don't know what's going to happen, I don't know if I'll be able to handle it."

That gives us somewhere different to work.

Instead of spending therapy trying to predict the future together, we can begin helping the client trust their ability to meet the future when it arrives.

Clinical Pearls

Look for the question underneath the question. A client may be asking for information when what they really want is certainty.

Follow the relief. If a behavior repeatedly produces immediate relief but the same fear keeps returning, explore whether it is maintaining the cycle.

Don't confuse uncertainty with danger. They are not the same thing, although anxiety often treats them as if they are.

Confidence is more durable than reassurance. We cannot promise clients that difficult things won't happen. We can help them discover that they are more capable of responding than anxiety tells them.

Keep the experiments small enough to create learning. The goal is not to overwhelm clients. It is to give them repeated opportunities to experience uncertainty without automatically trying to eliminate it.

Reflection Question

Think about a client who repeatedly brings new worries into therapy.

Are you helping them solve genuinely different problems—or could you both be working on different versions of the same underlying problem: the difficulty of not knowing?

Further Reading

For therapists interested in exploring this topic further, look for work by Michel Dugas and colleagues on the intolerance-of-uncertainty model of generalized anxiety disorder and behavioral experiments targeting beliefs about uncertainty.

Related Therapist Marketplace articles:

Why Reassurance Makes Anxiety Worse (And What Therapists Can Do Instead)

What Are Safety Behaviors? Examples, CBT Strategies & Therapy Guide

References

Buhr, K., & Dugas, M. J. (2002). The intolerance of uncertainty scale: Psychometric properties of the English version. Behaviour Research and Therapy, 40(8), 931–945.

Carleton, R. N. (2016). Into the unknown: A review and synthesis of contemporary models involving uncertainty. Journal of Anxiety Disorders, 39, 30–43.

Dugas, M. J., Gagnon, F., Ladouceur, R., & Freeston, M. H. (1998). Generalized anxiety disorder: A preliminary test of a conceptual model. Behaviour Research and Therapy, 36(2), 215–226.

Hebert, E. A., Dugas, M. J., Tulloch, T. G., & Holowka, D. W. (2022). Behavioral experiments for intolerance of uncertainty: A randomized clinical trial for adults with generalized anxiety disorder. Behavior Therapy.

McEvoy, P. M., & Mahoney, A. E. J. (2012). To be sure, to be sure: Intolerance of uncertainty mediates symptoms of various anxiety disorders and depression. Behavior Therapy, 43(3), 533–545.

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