The most common stress reactions include:

- The slowing of reaction time

- Slowness of thought

- Difficulty prioritizing tasks

- Difficulty initiating routine tasks

- Preoccupation with minor issues and familiar tasks

- Indecision and lack of concentration

- Loss of initiative with fatigue

- Exhaustion

Combat stress reaction symptoms align with the symptoms also found in psychological trauma, which is closely related to post-traumatic stress disorder (PTSD). CSR differs from PTSD (among other things) in that a PTSD diagnosis requires a duration of symptoms over one month, which CSR does not.

Shell shock is a phrase coined in World War I to describe the type of posttraumatic stress disorder many soldiers were afflicted with during the war (before PTSD itself was a term).

It is reaction to the intensity of the bombardment and fighting that produced a helplessness appearing variously as panic and being scared, or flight, an inability to reason, sleep, walk or talk.

During the War, the concept of shell shock was ill-defined. Cases of 'shell shock' could be interpreted as either a physical or psychological injury, or simply as a lack of moral fibre. The term "shell shock" is still used by the Veterans Administration to describe certain parts of PTSD but mostly it has entered into popular imagination and memory, and is often identified as the signature injury of the War.

In World War II and thereafter, diagnosis of 'shell shock' was replaced by that of combat stress reaction, a similar but not identical response to the trauma of warfare and bombardment.

During the early stages of World War I, soldiers from the British Expeditionary Force began to report medical symptoms after combat, including tinnitus, amnesia, headaches, dizziness, tremors, and hypersensitivity to noise. While these symptoms resembled those that would be expected after a physical wound to the brain, many of those reporting sick showed no signs of head wounds. By December 1914 as many as 10% of British officers and 4% of enlisted men were suffering from "nervous and mental shock".

The term "shell shock" came into use to reflect an assumed link between the symptoms and the effects of explosions from artillery shells. The term was first published in 1915 in an article in "The Lancet" by Charles Myers. Some 60–80% of shell shock cases displayed acute neurasthenia, while 10% displayed what would now be termed symptoms of conversion disorder, including mutism and fugue.

The number of shell shock cases grew during 1915 and 1916 but it remained poorly understood medically and psychologically. Some doctors held the view that it was a result of hidden physical damage to the brain, with the shock waves from bursting shells creating a cerebral lesion that caused the symptoms and could potentially prove fatal. Another explanation was that shell shock resulted from poisoning by the carbon monoxide formed by explosions.

At the same time an alternative view developed describing shell shock as an emotional, rather than a physical, injury. Evidence for this point of view was provided by the fact that an increasing proportion of men suffering shell shock symptoms had not been exposed to artillery fire. Since the symptoms appeared in men who had no proximity to an exploding shell, the physical explanation was clearly unsatisfactory.

In spite of this evidence, the British Army continued to try to differentiate those whose symptoms followed explosive exposure from others. In 1915 the British Army in France was instructed that:

However, it often proved difficult to identify which cases were which, as the information on whether a casualty had been close to a shell explosion or not was rarely provided.

The "DSM-IV" specifies that ASD must be accompanied by the presence of dissociative symptoms, which largely differentiates it from PTSD.

Dissociative symptoms include a sense of numbing or detachment from emotional reactions, a sense of physical detachment, such as seeing oneself from another perspective, decreased awareness of one’s surroundings, the perception that one’s environment is unreal or dreamlike, and the inability to recall critical aspects of the traumatic event (dissociative amnesia).

In addition to the characteristic dissociative symptoms, ASD shares many of the symptoms with PTSD, including:

- the experience or witnessing of a threatening event that resulted in intense fear or horror

- the re-experiencing of the event by means of flashbacks, recurrent thoughts or dreams, and distress when reminded of the event

- the avoidance of stimuli that serve as reminders of the event, such as feelings, thoughts, places, individuals, and activities

- anxiety, including restlessness, difficulty sleeping and concentrating, and hypervigilance

- a significant disruption in normal social or work functioning

The term ASR was first used to describe the symptoms of soldiers during World War I and II, and it was therefore also termed combat stress reaction (CSR). Approximately 20% of U.S. troops displayed symptoms of CSR during WWII, and it was assumed to be a temporary response of healthy individuals to witnessing or experiencing traumatic events. Symptoms include depression, anxiety, withdrawal, confusion, paranoia and sympathetic hyperactivity.

The APA officially included the term ASD in the "DSM-IV" in 1994, and prior to that, symptomatic individuals within the first month of trauma were diagnosed with adjustment disorder. According to the "DSM IV", ASR refers to the symptoms experienced right after exposure to a traumatic event, up until 48 hours after it. In contrast, ASD is defined by symptoms experienced after 48 hours of the event, up until one month past the event. Symptoms experienced for longer than one month are consistent with a diagnosis of PTSD.

According to an April 2010 U.S. Department of Veterans Affairs (VA) sponsored study conducted by the Institute of Medicine (IOM), part of the U.S. National Academy of Sciences, 250,000 of the 696,842 U.S. servicemen and women in the 1991 Gulf War continue to suffer from chronic multi-symptom illness, popularly known as "Gulf War Illness" or "Gulf War Syndrome." The IOM found that the chronic multi-symptom illness continues to affect these veterans nearly 20 years after the war.

According to the IOM, "It is clear that a significant portion of the soldiers deployed to the Gulf War have experienced troubling constellations of symptoms that are difficult to categorize," said committee chair Stephen L. Hauser, professor and chair, department of neurology, University of California, San Francisco (UCSF). "Unfortunately, symptoms that cannot be easily quantified are sometimes incorrectly dismissed as insignificant and receive inadequate attention and funding by the medical and scientific establishment. Veterans who continue to suffer from these symptoms deserve the very best that modern science and medicine can offer to speed the development of effective treatments, cures, and—we hope—prevention. Our report suggests a path forward to accomplish this goal, and we believe that through a concerted national effort and rigorous scientific input, answers can be found."

Questions still exist regarding why certain veterans showed, and still show, medically unexplained symptoms while others did not, why symptoms are diverse in some and specific in others, and why combat exposure is not consistently linked to having or not having symptoms. The lack of data on veterans' pre-deployment and immediate post-deployment health status and lack of measurement and monitoring of the various substances to which veterans may have been exposed make it difficult—and in many cases impossible—to reconstruct what happened to service members during their deployments nearly 20 years after the fact, the committee noted. The report called for a substantial commitment to improving identification and treatment of multisymptom illness in Gulf War veterans focussing on continued monitoring of Gulf War veterans, improved medical care, examination of genetic differences between symptomatic and asymptomatic groups and studies of environment-gene interactions.

A variety of signs and symptoms have been associated with GWS:

Birth defects have been suggested as a consequence of Gulf War deployment. However, a 2006 review of several studies of international coalition veterans' children found no strong or consistent evidence of an increase in birth defects, finding a modest increase in birth defects that was within the range of the general population, in addition to being unable to exclude recall bias as an explanation for the results. A 2008 report stated that "it is difficult to draw firm conclusions related to birth defects and pregnancy outcomes in Gulf War veterans", observing that while there have been "significant, but modest, excess rates of birth defects in children of Gulf War veterans", the "overall rates are still within the normal range found in the general population". The same report called for more research on the issue.

Medical ailments associated with Gulf War syndrome have been recognized by both the Department of Defense and the Department of Veterans Affairs. Since so little concrete information was known about this condition the Veterans Health Administration (VHA) originally classified individuals with related ailments believed to be connected to their service in the Persian Gulf a special non-ICD-9 code DX111, as well as ICD-9 code V65.5. There is no formal definition of the term "Gulf War syndrome" or "Gulf War illnesses".

A self-inflicted wound (SIW), is the act of harming oneself where there are no underlying psychological problems related to the self-injury, but where the injurer wanted to take advantage of being injured.

People who go through these types of extremely traumatic experiences often have certain symptoms and problems afterward. The severity of these symptoms depends on the person, the type of trauma involved, and the emotional support they receive from others. Reactions to and symptoms of trauma can be wide and varied, and differ in severity from person to person. A traumatized individual may experience one or several of them.

After a traumatic experience, a person may re-experience the trauma mentally and physically, hence trauma reminders, also called triggers, can be uncomfortable and even painful. It can damage people’s sense of safety, self, self-efficacy, as well as the ability to regulate emotions and navigate relationships. They may turn to psychoactive substances including alcohol to try to escape or dampen the feelings. These triggers cause flashbacks, which are dissociative experiences where the person feels as though the events is reoccurring. They can range from distracting to complete dissociation or loss of awareness of the current context. Re-experiencing symptoms are a sign that the body and mind are actively struggling to cope with the traumatic experience.

Triggers and cues act as reminders of the trauma, and can cause anxiety and other associated emotions. Often the person can be completely unaware of what these triggers are. In many cases this may lead a person suffering from traumatic disorders to engage in disruptive or self-destructive coping mechanisms, often without being fully aware of the nature or causes of their own actions. Panic attacks are an example of a psychosomatic response to such emotional triggers.

Consequently, intense feelings of anger may frequently surface, sometimes in inappropriate or unexpected situations, as danger may always seem to be present, as much as it is actually present and experienced from past events. Upsetting memories such as images, thoughts, or flashbacks may haunt the person, and nightmares may be frequent. Insomnia may occur as lurking fears and insecurity keep the person vigilant and on the lookout for danger, both day and night. Trauma doesn't only cause changes in one's daily functions but could also lead to morphological changes. Such epigenetic changes can be passed on to the next generations, thus making genetics as one of the components of the causes of psychological trauma. However, some people are born with or later develop protective factors such as genetics and sex that help lower their risk of psychological trauma.

The person may not remember what actually happened, while emotions experienced during the trauma may be re-experienced without the person understanding why (see Repressed memory). This can lead to the traumatic events being constantly experienced as if they were happening in the present, preventing the subject from gaining perspective on the experience. This can produce a pattern of prolonged periods of acute arousal punctuated by periods of physical and mental exhaustion. This can lead to mental health disorders like acute stress and anxiety disorder, traumatic grief, undifferentiated somatoform disorder, conversion disorders, brief psychotic disorder, borderline personality disorder, adjustment disorder...etc.

In time, emotional exhaustion may set in, leading to distraction, and clear thinking may be difficult or impossible. Emotional detachment, as well as dissociation or "numbing out", can frequently occur. Dissociating from the painful emotion includes numbing all emotion, and the person may seem emotionally flat, preoccupied, distant, or cold. Dissociation includes depersonalisation disorder, dissociative amnesia, dissociative fugue, dissociative identity disorder, etc. Exposure to and re-experiencing trauma can cause neurophysiological changes like slowed myelination, abnormalities in synaptic pruning, shrinking of the hippocampus, cognitive and affective impairment. This is significant in brain scan studies done regarding higher order function assessment with children and youth who were in vulnerable environments.

Some traumatized people may feel permanently damaged when trauma symptoms do not go away and they do not believe their situation will improve. This can lead to feelings of despair, transient paranoid ideation, loss of self-esteem, profound emptiness, suicidality, and frequently depression. If important aspects of the person's self and world understanding have been violated, the person may call their own identity into question. Often despite their best efforts, traumatized parents may have difficulty assisting their child with emotion regulation, attribution of meaning, and containment of post-traumatic fear in the wake of the child's traumatization, leading to adverse consequences for the child. In such instances, it is in the interest of the parent(s) and child for the parent(s) to seek consultation as well as to have their child receive appropriate mental health services.

Survivor guilt (or survivor's guilt; also called survivor syndrome or survivor's syndrome) is a mental condition that occurs when a person believes they have done something wrong by surviving a traumatic event when others did not. It may be found among survivors of murder, terrorism, combat, natural disasters, epidemics, among the friends and family of those who have died by suicide, and in non-mortal situation. The experience and manifestation of survivor's guilt will depend on an individual's psychological profile. When the "Diagnostic and Statistical Manual of Mental Disorders IV" (DSM-IV) was published, survivor guilt was removed as a recognized specific diagnosis, and redefined as a significant symptom of post traumatic stress disorder (PTSD).

Psychological trauma is a type of damage to the mind that occurs as a result of a severely distressing event. Trauma is often the result of an overwhelming amount of stress that exceeds one's ability to cope, or integrate the emotions involved with that experience. A traumatic event involves one's experience, or repeating events of being overwhelmed that can be precipitated in weeks, years, or even decades as the person struggles to cope with the immediate circumstances, eventually leading to serious, long-term negative consequences.

However, trauma differs between individuals, according to their subjective experiences. People will react to similar events differently. In other words, not all people who experience a potentially traumatic event will actually become psychologically traumatized. However, it is possible to develop posttraumatic stress disorder (PTSD) after being exposed to a potentially traumatic event.

This discrepancy in risk rate can be attributed to protective factors some individuals may have that enable them to cope with trauma; they are related to temperamental and environmental factors. Some examples are mild exposure to stress early in life, resilience characteristics, and active seeking of help.

Physical symptoms include:

- palpitations

- anorexia

- dry mouth

- insomnia

- thoracic/chest pressure

- respiratory difficulties

- epigastric mass

- headache

- a whole-body sensation of heat (distinct from heat intolerance, a symptom of hyperthyroidism)

Psychological symptoms include:

- being easily startled

- externalization of anger, also known in Korean as "bun" (분, 憤, "eruption of anger"), a Korean culture-related sentiment related to social unfairness

- generally sad mood

- frequent sighing

- a feeling of "eok-ul" (억울, 抑鬱, [feeling of] unfairness)

- being easily agitated

- feelings of guilt

- feelings of impending doom

Diagnosed patients may also have a medical history of prior major depressive disorder, dysthymic disorder, anxiety disorders, somatoform disorders, or adjustment disorder according to the "Diagnostic and Statistical Manual of Mental Disorders", fourth edition (DSM-IV) criteria.

Diagnosed patients are most likely to be middle-aged, post-menopausal women with low socio-economic status.

Symptoms of PTSD generally begin within the first 3 months after the inciting traumatic event, but may not begin until years later. In the typical case, the individual with PTSD persistently avoids trauma-related thoughts and emotions, and discussion of the traumatic event, and may even have amnesia of the event. However, the event is commonly relived by the individual through intrusive, recurrent recollections, flashbacks, and nightmares. While it is common to have symptoms after any traumatic event, these must persist to a sufficient degree (i.e., causing dysfunction in life or clinical levels of distress) for longer than one month after the trauma to be classified as PTSD (clinically significant dysfunction or distress for less than one month after the trauma may be acute stress disorder).

Posttraumatic stress disorder (PTSD) is a mental disorder that can develop after a person is exposed to a traumatic event, such as sexual assault, warfare, traffic collisions, or other threats on a person's life. Symptoms may include disturbing thoughts, feelings, or dreams related to the events, mental or physical distress to trauma-related cues, attempts to avoid trauma-related cues, alterations in how a person thinks and feels, and an increase in the fight-or-flight response. These symptoms last for more than a month after the event. Young children are less likely to show distress but instead may express their memories through play. A person with PTSD is at a higher risk for suicide and intentional self-harm.

Most people who have experienced a traumatic event will not develop PTSD. People who experience interpersonal trauma (for example rape or child abuse) are more likely to develop PTSD, as compared to people who experience non-assault based trauma such as accidents and natural disasters. About half of people develop PTSD following rape. Children are less likely than adults to develop PTSD after trauma, especially if they are under ten years of age. Diagnosis is based on the presence of specific symptoms following a traumatic event.

Prevention may be possible when therapy is targeted at those with early symptoms but is not effective when carried out among all people following trauma. The main treatments for people with PTSD are counselling and medication. A number of different types of therapy may be useful. This may occur one-on-one or in a group. Antidepressants of the selective serotonin reuptake inhibitor type are the first-line medications for PTSD and result in benefit in about half of people. These benefits are less than those seen with therapy. It is unclear if using medications and therapy together has greater benefit. Other medications do not have enough evidence to support their use and in the case of benzodiazepines may worsen outcomes.

In the United States about 3.5% of adults have PTSD in a given year, and 9% of people develop it at some point in their life. In much of the rest of the world, rates during a given year are between 0.5% and 1%. Higher rates may occur in regions of armed conflict. It is more common in women than men. Symptoms of trauma-related mental disorders have been documented since at least the time of the ancient Greeks. During the World Wars study increased and it was known under various terms including "shell shock" and "combat neurosis". The term "posttraumatic stress disorder" came into use in the 1970s in large part due to the diagnoses of U.S. military veterans of the Vietnam War. It was officially recognized by the American Psychiatric Association in 1980 in the third edition of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-III).

Hwabyeong or Hwabyung is a Korean somatization disorder, a mental illness which arises when people are unable to confront their anger as a result of conditions which they perceive to be unfair.

Hwabyung is a colloquial and somewhat inaccurate name, as it refers to the etiology of the disorder rather than its symptoms or apparent characteristics. Hwabyung is known as a culture-bound syndrome. The word hwabyung is composed of "hwa" (the Sino-Korean word for "fire" which can also contextually mean "anger") and "byung" (the Sino-Korean word for "syndrome" or "illness"). In South Korea, it may also be called "ulhwabyeong" (), literally "depression anger illness". In one survey, 4.1% of the general population in a rural area in Korea were reported as having hwabyung. Another survey shows that about 35% of Korean workers are affected by this condition at some time.

The diagnosis of PTSD was originally developed for adults who had suffered from a single event trauma, such as rape, or a traumatic experience during a war. However, the situation for many children is quite different. Children can suffer chronic trauma such as maltreatment, family violence, and a disruption in attachment to their primary caregiver. In many cases, it is the child's caregiver who caused the trauma. The diagnosis of PTSD does not take into account how the developmental stages of children may affect their symptoms and how trauma can affect a child’s development.

The term developmental trauma disorder (DTD) has also been suggested. This developmental form of trauma places children at risk for developing psychiatric and medical disorders. Bessel van der Kolk explains DTD as numerous encounters with interpersonal trauma such as physical assault, sexual assault, violence or death. It can also be characterized by subjective events like betrayal, defeat or shame.

Repeated traumatization during childhood leads to symptoms that differ from those described for PTSD. Cook and others describe symptoms and behavioural characteristics in seven domains:

- "Attachment" – "problems with relationship boundaries, lack of trust, social isolation, difficulty perceiving and responding to others' emotional states"

- "Biology" – "sensory-motor developmental dysfunction, sensory-integration difficulties, somatization, and increased medical problems"

- "Affect or emotional regulation" – "poor affect regulation, difficulty identifying and expressing emotions and internal states, and difficulties communicating needs, wants, and wishes"

- "Dissociation" – "amnesia, depersonalization, discrete states of consciousness with discrete memories, affect, and functioning, and impaired memory for state-based events"

- "Behavioural control" – "problems with impulse control, aggression, pathological self-soothing, and sleep problems"

- "Cognition" – "difficulty regulating attention, problems with a variety of 'executive functions' such as planning, judgement, initiation, use of materials, and self-monitoring, difficulty processing new information, difficulty focusing and completing tasks, poor object constancy, problems with 'cause-effect' thinking, and language developmental problems such as a gap between receptive and expressive communication abilities."

- "Self-concept" – "fragmented and disconnected autobiographical narrative, disturbed body image, low self-esteem, excessive shame, and negative internal working models of self".

Paruresis ( ) is a type of phobia in which the sufferer is unable to urinate in the real or imaginary presence of others, such as in a public restroom. The analogous condition that affects bowel movement is called parcopresis.

Adults with C-PTSD have sometimes experienced prolonged interpersonal traumatization as children as well as prolonged trauma as adults. This early injury interrupts the development of a robust sense of self and of others. Because physical and emotional pain or neglect was often inflicted by attachment figures such as caregivers or older siblings, these individuals may develop a sense that they are fundamentally flawed and that others cannot be relied upon.

This can become a pervasive way of relating to others in adult life described as insecure attachment. The diagnosis of dissociative disorder and PTSD in the current DSM-5 (2013) do not include insecure attachment as a symptom. Individuals with Complex PTSD also demonstrate lasting personality disturbances with a significant risk of revictimization.

Six clusters of symptoms have been suggested for diagnosis of C-PTSD:

- alterations in regulation of affect and impulses;

- alterations in attention or consciousness;

- alterations in self-perception;

- alterations in relations with others;

- somatization;

- alterations in systems of meaning.

Experiences in these areas may include:

- Difficulties regulating emotions, including symptoms such as persistent dysphoria, chronic suicidal preoccupation, self injury, explosive or extremely inhibited anger (may alternate), or compulsive or extremely inhibited sexuality (may alternate).

- Variations in consciousness, including forgetting traumatic events (i.e., psychogenic amnesia), reliving experiences (either in the form of intrusive PTSD symptoms or in ruminative preoccupation), or having episodes of dissociation.

- Changes in self-perception, such as a chronic and pervasive sense of helplessness, paralysis of initiative, shame, guilt, self-blame, a sense of defilement or stigma, and a sense of being completely different from other human beings.

- Varied changes in the perception of the perpetrator, such as attributing total power to the perpetrator, becoming preoccupied with the relationship to the perpetrator, including a preoccupation with revenge, idealization or paradoxical gratitude, seeking approval from the perpetrator, a sense of a special relationship with the perpetrator or acceptance of the perpetrator's belief system or rationalizations.

- Alterations in relations with others, including isolation and withdrawal, persistent distrust, anger and hostility, a repeated search for a rescuer, disruption in intimate relationships and repeated failures of self-protection.

- Loss of, or changes in, one's system of meanings, which may include a loss of sustaining faith or a sense of hopelessness and despair.

- Disconnection from surroundings accompanied by feelings of terror and confusion.

Video game-related health problems can induce repetitive strain injuries, skin disorders or other health issues. Other problems include video game-provoked seizures in patients with epilepsy. In rare and extreme cases, deaths have resulted from excessive video game playing (see Deaths due to video game addiction).

Claustrophobia is typically thought to have two key symptoms: fear of restriction and fear of suffocation. A typical claustrophobic will fear restriction in at least one, if not several, of the following areas: small rooms, locked rooms, MRI or CAT scan apparatus, cars, airplanes, trains, tunnels, underwater caves, cellars, elevators and caves. Additionally, the fear of restriction can cause some claustrophobia to fear trivial matters such as sitting in a haircutter's chair or waiting in line at a grocery store simply out of a fear of confinement to a single space. Another possible site for claustrophobic attacks is a dentist's chair, particularly during dental surgery; in that scenario, the fear is not of pain, but of being confined.

Often, when confined to an area, claustrophobics begin to fear suffocation, believing that there may be a lack of air in the area to which they are confined.

Ephebiphobia is the fear of youth. First coined as the "fear or loathing of teenagers", today the phenomenon is recognized as the "inaccurate, exaggerated and sensational characterization of young people" in a range of settings around the world. Studies of the fear of youth occur in sociology and youth studies.

Claustrophobia is the fear of having no escape, and being closed into a small space. It is typically classified as an anxiety disorder and often times results in a rather severe panic attack. It is also confused sometimes with Cleithrophobia (the fear of being trapped).

It appears that paruresis involves a tightening of the sphincter and/or bladder neck due to a sympathetic nervous system response. The adrenaline rush that produces the involuntary nervous system response probably has peripheral and central nervous system involvement. The internal urethral sphincter (smooth muscle tissue) or the external urethral sphincter (striated muscle), levator ani (especially the pubococcygeus) muscle area, or some combination of the above, may be involved. It is possible that there is an inhibition of the detrusor command through a reflex pathway as well. The pontine micturition center (Barrington's nucleus) also may be involved, as its inhibition results in relaxation of the detrusor and prevents the relaxation of the internal sphincter.

Exsanguination is the process of blood loss, to a degree sufficient to cause death. One does not have to lose all of one's blood to cause death. Depending upon the age, health, and fitness level of the individual, people can die from losing half to two-thirds of their blood; a loss of roughly one-third of the blood volume is considered very serious. Even a single deep cut can warrant suturing and hospitalization, especially if trauma, a vein or artery, or another comorbidity is involved. It is most commonly known as "bleeding to death" or colloquially as "bleeding out". The word itself originated from Latin: "ex" ("out of") and "sanguis" ("blood").