Emetophobia is a phobia that causes overwhelming, intense anxiety pertaining to vomiting. This specific phobia can also include subcategories of what causes the anxiety, including a fear of vomiting in public, a fear of seeing vomit, a fear of watching the action of vomiting or fear of being nauseated. It is common for emetophobics to be underweight, or even anorexic, due to strict diets and restrictions they make for themselves. The thought of someone possibly vomiting can cause the phobic person to engage in extreme behaviors to escape the perceived (and sometimes very real) threat of that particular situation, in which the phobic person will go to great lengths to avoid even potential situations that could even be perceived as "threatening".

Emetophobia is clinically considered an "elusive predicament" because limited research has been done pertaining to it. The fear of vomiting receives little attention compared with other irrational fears. Emetophobia is not limited by age or maturity level. There are cases of emetophobia present in childhood and adolescence, as well as adulthood.

The event of vomiting may scare away anyone with this peculiar phobia. Some may fear someone throwing up while another may fear themselves throwing up. Some may have both.

Some may have anxiety which makes them feel like they will throw up when it actually might not. People with Emetophobia usually suffer from anxiety, they often scream or cry when someone or something has been sick.

The root word for emetophobia is "emesis", from the Greek word "emein" which means "an act or instance of vomiting" with "-phobia” meaning "an exaggerated usually inexplicable fear of a particular object, class of objects, or situation."

People with emetophobia frequently report a vomit related traumatic event, such as a long bout of stomach flu, accidentally vomiting in public, or having to witness someone else vomit, as the start of the emetophobia. They may also be afraid of hearing that someone is feeling like vomiting or that someone has vomited, usually in conjunction with the fears of seeing someone vomit or seeing vomit.

Specific food avoidances could be caused by food phobias that cause great anxiety when a person is presented with new or feared foods. Most eating disorders are related to a fear of gaining weight. Those who suffer from ARFID do not have this fear, but the psychological symptoms and anxiety created is similar. Some sufferers of ARFID have fears such as Emetophobia (fear of vomiting) or a fear of choking.

The fifth edition of the "Diagnostic and Statistical Manual of Mental Disorders" (DSM-5) renamed "Feeding Disorder of Infancy or Early Childhood" to Avoidant/Restrictive Food Intake Disorder, and broadened the diagnostic criteria. Previously defined as a disorder exclusive to children and adolescents, the DSM-5 broadened the disorder to include adults who limit their eating and are affected by related physiological or psychological problems, but who do not fall under the definition of another eating disorder.

The DSM-5 defines the following diagnostic criteria:

- Disturbance in eating or feeding, as evidenced by one or more of:

- Substantial weight loss (or, in children, absence of expected weight gain)

- Nutritional deficiency

- Dependence on a feeding tube or dietary supplements

- Significant psychosocial interference

- Disturbance not due to unavailability of food, or to observation of cultural norms

- Disturbance not due to anorexia nervosa or bulimia nervosa, and no evidence of disturbance in experience of body shape or weight

- Disturbance not better explained by another medical condition or mental disorder, or when occurring concurrently with another condition, the disturbance exceeds what is normally caused by that condition

In previous years, the DSM was not inclusive in recognizing all of the challenges associated with feeding and eating disorders in 3 main domains:

- Eating Disorders Not Otherwise Specified (EDNOS) was an all-inclusive, placeholder group for all individuals that presented challenges with feeding

- The category of Feeding Disorder of Infancy/ Early Childhood was noted to be too broad, limiting specification when treating these behaviors

- There are children and youth who present feeding challenges but do not fit within any existing categories to date

Children are often picky eaters, this does not necessarily mean they meet the criteria for an ARFID diagnosis. In addition, self-identification as having ARFID may contribute to ARFID.

There are multiple medical conditions which may be misdiagnosed as a primary psychiatric disorder, complicating or delaying treatment. These may have a synergistic effect on conditions which mimic an eating disorder or on a properly diagnosed eating disorder.

- Lyme disease which is known as the "great imitator", as it may present as a variety of psychiatric or neurological disorders including anorexia nervosa.

- Gastrointestinal diseases, such as celiac disease, Crohn's disease, peptic ulcer, eosinophilic esophagitis or non-celiac gluten sensitivity, among others. Celiac disease is also known as the "great imitator", because it may involve several organs and cause an extensive variety of non-gastrointestinal symptoms, such as psychiatric and neurological disorders, including anorexia nervosa.

- Addison's Disease is a disorder of the adrenal cortex which results in decreased hormonal production. Addison's disease, even in subclinical form may mimic many of the symptoms of anorexia nervosa.

- Gastric adenocarcinoma is one of the most common forms of cancer in the world. Complications due to this condition have been misdiagnosed as an eating disorder.

- Hypothyroidism, hyperthyroidism, hypoparathyroidism and hyperparathyroidism may mimic some of the symptoms of, can occur concurrently with, be masked by or exacerbate an eating disorder.

- Toxoplasma seropositivity: even in the absence of symptomatic toxoplasmosis, toxoplasma gondii exposure has been linked to changes in human behavior and psychiatric disorders including those comorbid with eating disorders such as depression. In reported case studies the response to antidepressant treatment improved only after adequate treatment for toxoplasma.

- Neurosyphilis: It is estimated that there may be up to one million cases of untreated syphilis in the US alone. "The disease can present with psychiatric symptoms alone, psychiatric symptoms that can mimic any other psychiatric illness". Many of the manifestations may appear atypical. Up to 1.3% of short term psychiatric admissions may be attributable to neurosyphilis, with a much higher rate in the general psychiatric population. (Ritchie, M Perdigao J,)

- Dysautonomia: a wide variety of autonomic nervous system (ANS) disorders may cause a wide variety of psychiatric symptoms including anxiety, panic attacks and depression. Dysautonomia usually involves failure of sympathetic or parasympathetic components of the ANS system but may also include excessive ANS activity. Dysautonomia can occur in conditions such as diabetes and alcoholism.

Psychological disorders which may be confused with an eating disorder, or be co-morbid with one:

- Emetophobia is an anxiety disorder characterized by an intense fear of vomiting. A person so afflicted may develop rigorous standards of food hygiene, such as not touching food with their hands. They may become socially withdrawn to avoid situations which in their perception may make them vomit. Many who suffer from emetophobia are diagnosed with anorexia or self-starvation. In severe cases of emetophobia they may drastically reduce their food intake.

- Phagophobia is an anxiety disorder characterized by a fear of eating, it is usually initiated by an adverse experience while eating such as choking or vomiting. Persons with this disorder may present with complaints of pain while swallowing.

- Body dysmorphic disorder (BDD) is listed as a somatoform disorder that affects up to 2% of the population. BDD is characterized by excessive rumination over an actual or perceived physical flaw. BDD has been diagnosed equally among men and women. While BDD has been misdiagnosed as anorexia nervosa, it also occurs comorbidly in 39% of eating disorder cases. BDD is a chronic and debilitating condition which may lead to social isolation, major depression and suicidal ideation and attempts. Neuroimaging studies to measure response to facial recognition have shown activity predominately in the left hemisphere in the left lateral prefrontal cortex, lateral temporal lobe and left parietal lobe showing hemispheric imbalance in information processing. There is a reported case of the development of BDD in a 21-year-old male following an inflammatory brain process. Neuroimaging showed the presence of a new atrophy in the frontotemporal region.

Symptoms and complications vary according to the nature and severity of the eating disorder:

Some physical symptoms of eating disorders are weakness, fatigue, sensitivity to cold, reduced beard growth in men, reduction in waking erections, reduced libido, weight loss and failure of growth. Unexplained hoarseness may be a symptom of an underlying eating disorder, as the result of acid reflux, or entry of acidic gastric material into the laryngoesophageal tract. Patients who induce vomiting, such as those with anorexia nervosa, binge eating-purging type or those with purging-type bulimia nervosa are at risk for acid reflux. Polycystic ovary syndrome (PCOS) is the most common endocrine disorder to affect women. Though often associated with obesity it can occur in normal weight individuals. PCOS has been associated with binge eating and bulimic behavior. Other possible manifestations are dry lips, burning tongue, parotid gland swelling, and temporomandibular disorders.

The differential diagnoses of anorexia nervosa (AN) includes various types of medical and psychological conditions, which may be misdiagnosed as AN. In some cases, these conditions may be comorbid with AN because the misdiagnosis of AN is not uncommon. For example, a case of achalasia was misdiagnosed as AN and the patient spent two months confined to a psychiatric hospital. A reason for the differential diagnoses that surround AN arise mainly because, like other disorders, it is primarily, albeit defensively and adaptive for, the individual concerned.

Anorexia Nervosa is a psychological disorder characterized by extremely reduced intake of food. People suffering from Aneroxia Nervosa have a low self-image and consider themselves overweight.

Common behaviors and signs of someone suffering from AN:

- Forcing oneself to vigorously exercise even in adverse conditions or when their health does not permit it.

- Forcing own self to urinate and excrete waste product from the body.

- Using substituted amphetamines (stimulants that can reduce appetite) to reduce appetite.

- Skin turning yellow

There are various other psychological issues that may factor into anorexia nervosa, some fulfill the criteria for a separate Axis I diagnosis or a personality disorder which is coded Axis II and thus are considered comorbid to the diagnosed eating disorder. Axis II disorders are subtyped into 3 "clusters", A, B and C. The causality between personality disorders and eating disorders has yet to be fully established. Some people have a previous disorder which may increase their vulnerability to developing an eating disorder. Some develop them afterwards. The severity and type of eating disorder symptoms have been shown to affect comorbidity. These comorbid disorders themselves have multiple differential diagnoses, such as depression which may be caused by such disparate causes such as Lyme disease or hypothyroidism.

- Body dysmorphic disorder (BDD) is listed as a somatoform disorder that affects up to 2% of the population. BDD is characterized by excessive rumination over an actual or perceived physical flaw. BDD has been diagnosed equally among men and women. While BDD has been misdiagnosed as anorexia nervosa, it also occurs comorbidly in 25% to 39% of AN cases.

BDD is a chronic and debilitating condition which may lead to social isolation, major depression, suicidal ideation and attempts. Neuroimaging studies to measure response to facial recognition have shown activity predominately in the left hemisphere in the left lateral prefrontal cortex, lateral temporal lobe and left parietal lobe showing hemispheric imbalance in information processing. There is a reported case of the development of BDD in a 21 year old male following an inflammatory brain process. Neuroimaging showed the presence of new atrophy in the frontotemporal region.

- Emetophobia is an anxiety disorder characterized by an intense fear of vomiting. A person so afflicted may develop rigorous standards of food hygiene, such as not touching food with their hands. They may become socially withdrawn to avoid situations which in their perception may make them vomit. Many who suffer from emetophobia are diagnosed with anorexia or self-starvation. In severe cases of emetophobia they may drastically reduce their food intake.

- Food avoidance emotional disorder is an eating disorder that affects children which involves a fear of eating which is not accompanied by a fear of weight gain which may be misdiagnosed as anorexia nervosa.

- phagophobia is an anxiety disorder characterized by a fear of eating, it is usually initiated by an adverse experience while eating such as choking or vomiting. Individuals with this disorder may present with complaints of pain while swallowing. There have been cases of it being misdiagnosed as AN. A similar phobic anxiety disorder, swallowing phobia may also lead to a misdiagnosis of anorexia nervosa; such individuals do not want to lose weight but typically want to put weight back on that they have lost due to their phobia.

The distinction between the diagnoses of anorexia nervosa, bulimia nervosa and eating disorder not otherwise specified (EDNOS) is often difficult to make as there is considerable overlap between patients diagnosed with these conditions. Seemingly minor changes in a patient's overall behavior or attitude can change a diagnosis from "anorexia: binge-eating type" to bulimia nervosa. It is not unusual for a person with an eating disorder to "move through" various diagnoses as his or her behavior and beliefs change over time.