Medically Reviewed by Seth Gillihan, PhD

Fear is a healthy and adaptive human emotion — except when it becomes disproportionate to the source that’s causing it.

Fear is a natural and normal human experience. We all feel it from time to time, and there are situations when we rely on fear to keep us out of trouble.

“Fear is healthy and adaptive,” says Thompson Davis, PhD, a phobia specialist and chair of psychology at the University of Alabama in Tuscaloosa. “If we were not afraid of death and dying and getting hurt, we wouldn’t look both ways before crossing the street.”

While fear (like all our emotions) serves a purpose, Dr. Davis says it can also grow so great or disproportionate that it interferes with a person’s daily life. 

For example, fear of a snarling, barking stray dog is logical and appropriate, he says. On the other hand, a fear of dogs that prevents someone from going to parks or outdoor spaces — anywhere someone may be walking a dog — is the type of fear that likely requires a professional’s attention.

An overabundance of fear can also affect us on the inside. 

Fear can ramp up nervous system activity in some potentially unhealthy ways, according to StatPearls. It’s also closely associated with mood disorders such as anxiety and depression, and may in some cases reinforce or even give rise to these mental health conditions, Davis says.

Here, he and other experts explain what fear is, how it’s connected to health, and how people can prevent it from snowballing.

How Do Psychologists Define Fear?

In simple terms, fear is what a person feels when they are threatened. That’s according to a study in the American Journal of Psychiatry.

Types of Fear: Conditioned Fear Versus Innate Fear

Some experts break up fear into two different subtypes: conditioned (or learned) fear and innate fear. 

Conditioned fear is the type you acquire through experience, says Vadim Bolshakov, PhD, a neuroscientist and professor of psychiatry at Harvard Medical School in Boston. For example, you may have learned to fear water because you had an experience where you nearly drowned when you were a child. 

“Innate fear does not require learning,” he explains. No one needs to be taught to fear a snarling, snapping animal.

The Difference Between Fear and Anxiety

While fear is closely tied to emotions like anxiety, psychologists draw some distinctions between the two. “Fear has a clear object and target,” says Arash Javanbakht, MD, a psychiatrist and director of the Stress, Trauma, and Anxiety Research Clinic at Wayne State University in Detroit. “So if someone’s pointing a gun at me, I feel fear.”

Anxiety, on the other hand, is more vague or anticipatory. You’re worried that something bad could happen — for example, you could encounter someone with a gun — but that bad thing hasn’t actually happened yet. “You’re on high alert, but you’re not in immediate danger — that’s anxiety,” Dr. Javanbakht says.

Another way to distinguish between the two, says Davis, is to think of anxiety as being future-oriented. “Fear tends to be a reaction to an immediate threat, while anxiety is concern or a response to future events,” he says. 

It’s also common for fear to give rise to anxiety. “You can be afraid of dogs, and that can create anxiety about seeing a dog,” he says.

Many people have particular fears, such as a fear of snakes, heights, or being in enclosed spaces. In severe cases, a person may be diagnosed with a specific phobia, according to a StatPearls review on the topic. (More on this below.)

How Does Fear Affect Your Body and Health?

Fear begins when your brain, via your senses, becomes aware of a threat. For example, you see a large spider scuttling across the floor or you hear a tree limb snapping overhead.

According to a study published in 2017 in the Proceedings of the National Academy of Sciences, (PDF) there’s some expert disagreement when it comes to the exact brain circuits involved in fear. But much of the existing research suggests that the brain’s limbic system, and specifically the amygdala, are highly involved when a person experiences fear. Many of these same areas are also active during periods of anxiety.

“When you look at the brain networks that are more active in fear and anxiety, they very highly overlap,” Javanbakht says. 

“But the level of activity could be different,” he says. Typically, anxiety would produce a milder response than fear. 

Both emotions are forms of stress, and both activate the hypothalamus-pituitary-adrenal (HPA) axis, which leads to the release of stress hormones into the bloodstream, most notably cortisol. The sympathetic nervous system also kicks into high gear, activating the "fight, flight, or freeze" response through the release of adrenaline (epinephrine), research has shown.

When we feel fear, these internal responses make us more likely to fight, freeze, or flee — whatever can help neutralize the source of their fear, Dr. Bolshakov says. 

Anxiety, on the other hand, is more likely to trigger a state of alertness and risk-assessment, he says. For example, if you were walking through a park at night and felt on edge, you might notice that you’re extra sensitive to the crack of a branch or the rustle of leaves. You’re not freaking out, but your alertness is cranked up.

“There are also certain physiological manifestations associated with fear,” he says. “They may include increases in blood pressure, heart rate, and respiration rate.” Sweating is another symptom. Immune activity, including inflammation, also ramps up, according to research.

These internal responses are designed to help you survive a threatening encounter. But if these are turned on all the time — for example, if someone has an intense fear of social interactions or other commonplace experiences — the kind of chronic activation this causes can lead to health problems.

Some research has linked chronic stress, including stress caused by fear, to pain disorders and autoimmune conditions such as arthritis and inflammatory bowel disease. 

There may also be psychological consequences. “We’re starting to regard specific phobia as a gateway disorder,” Davis says. “So as time passes, phobias sometimes morph into more internalizing problems like anxiety and depression.” 

It’s not clear exactly how or why this happens, but it may be that some specific fears produce anxiety that, as time passes, becomes more frequent or generalized. “This is a particularly interesting area of research, and it’s possible that if you just treat the phobia, these other conditions get better, too,” he adds.

When Is Fear a Clinical Phobia Disorder?

This can be quite tricky. “It’s assumed that fear becomes ‘unhealthy’ when it is not proportional to the events or situations,” says Bolshakov. “But this is very subjective.”

Davis, who was a clinician and has treated people who have phobias, says there are two main criteria that will lead people to seek professional help for their fear. “If someone sees me, either their emotions are interfering with their life or they feel the intensity is over and above what most of us would feel,” he says.

He agrees that these criteria can be subjective and also dependent on a person’s circumstances. 

For example, if someone has a terrible fear of public speaking, but they never have to speak in public, their fear isn’t having a negative impact on their life. On the other hand, stage fright may be terribly disruptive for someone whose job demands giving speeches or presentations.

The formal diagnostic features of specific phobia clarify some of these points, according to the aforementioned StatPearls review. Fear may tip into disorder territory if:

• You actively and persistently avoid the source of your fear for six months or more
• Your fear or anxiety is out of proportion to the actual danger posed by the object or situation
• Your distress or impairment in social, occupational, or other important areas of life is a problem for you

“Most people are going to come to a practitioner for help because their fear is out of the realm of typical experience, and they want a professional to guide them through that,” Davis says.

How to Get Better at Facing Your Fears

If you spend any time talking with a fear expert, discussions of treatment (or how to overcome your fears) will lead quickly to one practice: exposure.

Exposure Therapy

“The most-supported evidence-based treatment for specific phobia in both children and adults is cognitive behavioral therapy with exposure, and the variant that is recommended is a particular type called exposure therapy,” Davis says. 

Yes, that means facing the source of your fears. But that’s only part of it. “You want to do that in a manageable way, and in an environment where you can challenge yourself in the middle range of your fear, not at a panic stage where it’s your worst fear realized,” Davis explains. 

For example, someone with a fear of dogs might spend time in the same room with a dog that is known to be completely gentle and docile. As they become more comfortable over time, they would take on progressively more challenging exposure situations.

Virtual reality is also becoming a popular tool in clinical exposure treatments. “Using augmented reality, I can put a tarantula in a patient’s real-life environment,” says Javanbakht, referencing some of his own research. “In less than an hour — 38 minutes is the average — the person will actually be able to touch a real tarantula.” 

Both he and Davis say that the cognitive part of cognitive behavioral therapy coupled with exposure can also be very beneficial. Cognitive therapy involves exploring the thoughts that arise during periods of fear and, in Javanbakht’s words, “challenging” them. Awareness of these thoughts and a careful examination of their validity can help people learn to set them aside or react to them less forcefully, he says.

If your fear is severe or disruptive to your life, exposure is best practiced with an expert’s guidance. (Done wrong, it could actually make your fear worse.) 

DIY Exposure Therapy

However, if your fear is mild, Davis says you could practice “exposure lite.”

“Start small,” he says. If you’re afraid of snakes, for example, try looking at pictures of snakes, or watch videos of people handling snakes. Over time, you could also visit a zoo and look at snakes in their secure enclosures. “Those safe exposures can help you adjust,” he says. 

If you notice you’re growing more comfortable around the source of your fear, that’s a sign it’s working. You can then work up slowly to more difficult situations. 

Breathing Exercises, Positive Self-Talk, and More

Breathing exercises and positive self-talk are other methods clinicians may recommend to help people manage their fear. If your fears are mild, these sorts of relaxation practices may help you control the racing heart and other physical symptoms of fear. Physicians will at times prescribe medication for a specific phobia. 

Fear is a natural human emotion that we all experience. But if yours has become a problem, know that there are ways to deal with it.