Signs of Fear

Medically Reviewed by Jennifer Casarella, MD on December 29, 2022
3 min read

Fear is a term that describes an emotional response in reaction to something that may be dangerous or threatening. On a day-to-day basis, many people experience fear ranging from nervousness about public speaking to intense phobias.

Situation-Specific Fear

People often feel temporary fear or nervousness responding to a stressful situation, like giving a presentation at work. Also, fleeting fear sometimes happens when startled, for example, if a snake crosses the path while gardening.

Temporary fear often resolves itself after the perceived threat is gone and is a useful self-protective instinct. However, chronic fear in the form of panic disorder, social anxiety, or a phobia may interfere with day-to-day life. These conditions are complicated and often require professional intervention.

Social Anxiety Disorder

Social Anxiety Disorder refers to a condition where someone feels anxious or fearful of some or all social interactions.

Panic Disorder

Panic disorder refers to a condition where an individual experiences sudden, overwhelming fear or anxiety that may last several minutes. Panic attacks are one symptom. The causes of panic disorder aren’t well understood.

Post-Traumatic Stress Disorder (PTSD)

PTSD refers to recurring fear triggered by past trauma such as an accident, war, or another dangerous event.


Humans experience a range of phobias. Some are very specific, such as an intense fear of flying or snakes. Others are more generalized, like social phobias or agoraphobia (a fear of public or open places). Depending on the severity, a chronic fear or phobia can interfere with an individual’s daily life and sense of wellbeing.

While people often think of fear as an emotional response, physical responses are also involved. During a frightening or stressful situation, people experience the “fight or flight” response.

The adrenal gland produces the hormones adrenaline and cortisol and triggers a chain reaction of physical responses. Here are some of the physical signs to look out for:

  • Increased heart rate
  • Faster breathing or shortness of breath
  • Butterflies or digestive changes
  • Sweating and chills
  • Trembling muscles

Changes in Heart Rate

In response to frightening situations, the body releases adrenaline, which triggers the body for action. The heart rate and breath rate increases in proportion to the level of perceived threat.

It isn’t just the heart rate that adrenaline impacts. Heart Rate Variability (HRV) is a measure of the variations between heartbeat intervals.

The autonomic nervous system manages bodily functions that are not consciously controlled, like a heartbeat. It has two main branches known as parasympathetic and sympathetic. The parasympathetic branch is associated with rest, while the sympathetic branch is associated with the body’s response to stress or exertion.

When both branches of the nervous system are balanced, an individual tends to have a higher degree of HRV compared to someone who is frequently afraid or otherwise stressed.

Shortness of Breath

Along with an increase in heart rate, people breathe at a faster rate when experiencing fear. Sometimes this may result in feeling a shortness of breath. When feeling frightened or panicked, people breathe at a faster rhythm.

Researchers at Northwestern University found this results in a lower proportion of time spent inhaling, which may prepare the brain for quick action.

Butterflies, Upset Stomach, or Nausea

The body produces cortisol in response to fear or stress. This hormone inhibits insulin production, so the muscles have immediate energy. After the frightening situation is over, the hormone balance returns to normal. This is one reason many people feel butterflies, upset stomach, or sometimes nausea when afraid.

Chills or Increased Sweating

In addition to increasing the heart rate and breathing, adrenaline can also increase sweating and sometimes chills. The chills happen because the hormone stimulates muscle contraction, including the tiny muscles that surround the hair follicles.

This is commonly known as “goosebumps,” which also happens when someone is cold. The expression about fear making the hair stand up refers to this physical response.


The hormones released when afraid work together to increase the muscle’s blood flow. Sometimes the muscles tremble while afraid and for a short time afterward.

Short-lived day to day fear may be beneficial as it alerts an individual to a perceived threat. Mindfulness and self-care techniques like breathing exercises often help to manage fear and other sources of stress.

People who experience more intense fear-related conditions like Social Anxiety Disorder, Panic disorder, PTSD, and various phobias may benefit from discussing the matter with a primary care physician or a behavioral health provider.  Many individuals are able to manage fear through a combination of medical interventions, mindfulness techniques, or talk therapy.