The ICD-10 defines hypochondriasis as follows:

The DSM-IV defines hypochondriasis according to the following criteria:

A. Preoccupation with fears of having, or the idea that one has, a serious disease based on the person's misinterpretation of bodily symptoms.

B. The preoccupation persists despite appropriate medical evaluation and reassurance.

C. The belief in Criterion A is not of delusional intensity (as in Delusional Disorder, Somatic Type) and is not restricted to a circumscribed concern about appearance (as in Body Dysmorphic Disorder).

D. The preoccupation causes clinically significant distress or impairment in

social, occupational, or other important areas of functioning.

E. The duration of the disturbance is at least 6 months.

F. The preoccupation is not better accounted for by Generalized Anxiety Disorder, Obsessive-Compulsive Disorder, Panic Disorder, a Major Depressive Episode, Separation Anxiety, or another Somatoform Disorder.

The newly published DSM-5 replaces the diagnosis of hypochondriasis with "illness anxiety disorder".

Most research indicates that cognitive behavioral therapy (CBT) is an effective treatment for hypochondriasis. Much of this research is limited by methodological issues. A small amount of evidence suggests that selective serotonin reuptake inhibitors can also reduce symptoms, but further research is needed.

The diagnosis of an anxiety disorder requires first ruling out an underlying medical cause. Diseases that may present similar to an anxiety disorder, including certain endocrine diseases (hypo- and hyperthyroidism, hyperprolactinemia), metabolic disorders (diabetes), deficiency states (low levels of vitamin D, B2, B12, folic acid), gastrointestinal diseases (celiac disease, non-celiac gluten sensitivity, inflammatory bowel disease), heart diseases, blood diseases (anemia), and brain degenerative diseases (Parkinson's disease, dementia, multiple sclerosis, Huntington's disease).

Also, several drugs can cause or worsen anxiety, whether in intoxication, withdrawal, or from chronic use. These include alcohol, tobacco, cannabis, sedatives (including prescription benzodiazepines), opioids (including prescription pain killers and illicit drugs like heroin), stimulants (such as caffeine, cocaine and amphetamines), hallucinogens, and inhalants.

The DSM-IV-TR diagnostic criteria for panic disorder require unexpected, recurrent panic attacks, followed in at least one instance by at least a month of a significant and related behavior change, a persistent concern of more attacks, or a worry about the attack's consequences. There are two types, one with and one without agoraphobia. Diagnosis is excluded by attacks due to a drug or medical condition, or by panic attacks that are better accounted for by other mental disorders.

The diagnostic criteria:

The essential feature is recurrent attacks of severe anxiety (panic), which are not restricted to any particular situation or set of circumstances and are therefore unpredictable.

The dominant symptoms include:

- sudden onset of palpitations

- chest pain

- choking sensations

- dizziness

- feelings of unreality (depersonalization or derealization)

- secondary fear of dying, losing control, or going mad

Panic disorder should not be given as the main diagnosis if the person has a depressive disorder at the time the attacks start; in these circumstances, the panic attacks are probably secondary to depression.

The Panic Disorder Severity Scale (PDSS) is a questionnaire for measuring the severity of panic disorder.

DSM-5 diagnostic criteria for a panic attack include a discrete period of intense fear or discomfort, in which four (or more) of the following symptoms developed abruptly and reached a peak within minutes:

- Palpitations, and/or accelerated heart rate

- Sweating

- Trembling or shaking

- Sensations of shortness of breath or being smothered

- Feeling of choking

- Chest pain or discomfort

- Nausea or abdominal distress

- Feeling dizzy, unsteady, lightheaded, or faint

- Derealization (feelings of unreality) or depersonalization (being detached from oneself)

- Fear of losing control or going insane

- Sense of impending death

- Paresthesias (numbness or tingling sensations)

- Chills or hot flashes

In DSM-5, culture-specific symptoms (e.g., tinnitus, neck soreness, headache, and uncontrollable screaming or crying) may be seen. Such symptoms should not count as one of the four required symptoms.

Some or all of these symptoms can be found in the presence of a pheochromocytoma.

Screening tools such as the Panic Disorder Severity Scale can be used to detect possible cases of disorder and suggest the need for a formal diagnostic assessment.

The American Psychiatric Association introduced GAD as a diagnosis in the DSM-III in 1980, when anxiety neurosis was split into GAD and panic disorder. The definition in the DSM-III required uncontrollable and diffuse anxiety or worry that is excessive and unrealistic and persists for 1 month or longer. High rates in comorbidity of GAD and major depression led many commentators to suggest that GAD would be better conceptualized as an aspect of major depression instead of an independent disorder. Many critics stated that the diagnostic features of this disorder were not well established until the DSM-III-R. Since comorbidity of GAD and other disorders decreased with time, the DSM-III-R changed the time requirement for a GAD diagnosis to 6 months or longer. The DSM-IV changed the definition of "excessive worry" and the number of associated psychophysiological symptoms required for a diagnosis. Another aspect of the diagnosis the DSM-IV clarified was what constitutes a symptom as occurring "often". The DSM-IV also required difficulty controlling the worry to be diagnosed with GAD. The DSM-5 emphasized that excessive worrying had to occur more days than not and on a number of different topics. It has been stated that the constant changes in the diagnostic features of the disorder have made assessing epidemiological statistics such as prevalence and incidence difficult, as well as increasing the difficulty for researchers in identifying the biological and psychological underpinnings of the disorder. Consequently, making specialized medications for the disorder is more difficult as well. This has led to the continuation of GAD being medicated heavily with SSRIs.

Most people who present to mental health specialists develop agoraphobia after the onset of panic disorder. Agoraphobia is best understood as an adverse behavioral outcome of repeated panic attacks and subsequent anxiety and preoccupation with these attacks that leads to an avoidance of situations where a panic attack could occur. Early treatment of panic disorder can often prevent agoraphobia. Agoraphobia is typically determined when symptoms are worse than panic disorder, but also do not meet the criteria for other anxiety disorders such as depression. In rare cases where agoraphobics do not meet the criteria used to diagnose panic disorder, the formal diagnosis of agoraphobia without history of panic disorder is used (primary agoraphobia).

As noted by Altman, McGoey & Sommer, it is important to observe the child, "in multiple contexts, on numerous occasions, and in their everyday environments (home, daycare, preschool)". It is beneficial to view parent and child interactions and behaviors that may contribute to SAD.

Dyadic Parent-Child Interaction Coding System and recently the Dyadic Parent-Child Interaction Coding System II (DPICS II) are methods used when observing parents and children interactions.

Separation Anxiety Daily Diaries (SADD) have also been used to “assess anxious behaviors along with their antecedents and consequences and may be particularly suited to SAD given its specific focus on parent–child separation” (Silverman & Ollendick, 2005). The diaries are carefully evaluated for validity.

At the preschool-aged stage, early identification and intervention is crucial. The communication abilities of young children are taken into consideration when creating age-appropriate assessments.

A commonly used assessment tool for preschool-aged children (ages 2–5) is the Preschool Age Psychiatric Assessment (PAPA). Additional questionnaires and rating scales that are used to assess the younger population include the Achenbach Scales, the Fear Survey Schedule for Infants and Preschoolers, and The Infant–Preschool Scale for Inhibited Behaviors.

Preschool children are also interviewed. Two interviews that are sometimes conducted are Attachment Doll-Play and Emotional Knowledge. In both of the assessments the interviewer depicts a scenario where separation and reunion occur; the child is then told to point at one of the four facial expressions presented. These facial expressions show emotions such as anger or sadness. The results are then analyzed.

Behavioral observations are also utilized when assessing the younger population. Observations enable the clinician to view some of the behaviors and emotions in specific contexts.

Anxiety disorders are often severe chronic conditions, which can be present from an early age or begin suddenly after a triggering event. They are prone to flare up at times of high stress and are frequently accompanied by physiological symptoms such as headache, sweating, muscle spasms, tachycardia, palpitations, and hypertension, which in some cases lead to fatigue.

In casual discourse the words "anxiety" and "fear" are often used interchangeably; in clinical usage, they have distinct meanings: "anxiety" is defined as an unpleasant emotional state for which the cause is either not readily identified or perceived to be uncontrollable or unavoidable, whereas "fear" is an emotional and physiological response to a recognized external threat. The term "anxiety disorder" includes fears (phobias) as well as anxieties.

The diagnosis of anxiety disorders is difficult because there are no objective biomarkers, it is based on symptoms, which typically need to be present at least six months, be more than would be expected for the situation, and decrease functioning. Several generic anxiety questionnaires can be used to detect anxiety symptoms, such as the State-Trait Anxiety Inventory (STAI), the Generalized Anxiety Disorder 7 (GAD-7), the Beck Anxiety Inventory (BAI), the Zung Self-Rating Anxiety Scale, and the Taylor Manifest Anxiety Scale. Other questionnaires combine anxiety and depression measurement, such as the Hamilton Anxiety Rating Scale, the Hospital Anxiety and Depression Scale (HADS), the Patient Health Questionnaire (PHQ), and the Patient-Reported Outcomes Measurement Information System (PROMIS). Examples of specific anxiety questionnaires include the Liebowitz Social Anxiety Scale (LSAS), the Social Interaction Anxiety Scale (SIAS), the Social Phobia Inventory (SPIN), the Social Phobia Scale (SPS), and the Social Anxiety Questionnaire (SAQ-A30).

Anxiety disorders often occur along with other mental disorders, in particular depression, which may occur in as many as 60% of people with anxiety disorders. The fact that there is considerable overlap between symptoms of anxiety and depression, and that the same environmental triggers can provoke symptoms in either condition, may help to explain this high rate of comorbidity.

Studies have also indicated that anxiety disorders are more likely among those with family history of anxiety disorders, especially certain types.

Sexual dysfunction often accompanies anxiety disorders, although it is difficult to determine whether anxiety causes the sexual dysfunction or whether they arise from a common cause. The most common manifestations in individuals with anxiety disorder are avoidance of intercourse, premature ejaculation or erectile dysfunction among men and pain during intercourse among women. Sexual dysfunction is particularly common among people affected by panic disorder (who may fear that a panic attack will occur during sexual arousal) and posttraumatic stress disorder.

ICD-10 defines social phobia as a fear of scrutiny by other people leading to avoidance of social situations. The anxiety symptoms may present as a complaint of blushing, hand tremor, nausea or urgency of micturition. Symptoms may progress to panic attacks.

Standardized rating scales such as the Social Phobia Inventory, the SPAI-B, Liebowitz Social Anxiety Scale, and the Social Interaction Anxiety Scale can be used to screen for social anxiety disorder and measure the severity of anxiety.

The diagnostic criteria for GAD as defined by the Diagnostic and Statistical Manual of Mental Disorders DSM-5 (2013), published by the American Psychiatric Association, are paraphrased as follows:

No major changes to GAD have occurred since publication of the Diagnostic and Statistical Manual of Mental Disorders (2004); minor changes include wording of diagnostic criteria.

According to the fourth revision of the "Diagnostic and Statistical Manual of Mental Disorders", phobias can be classified under the following general categories:

- Animal type – Fear of dogs, cats, rats and/or mice, pigs, cows, birds, spiders, or snakes.

- Natural environment type – Fear of water (aquaphobia), heights (acrophobia), lightning and thunderstorms (astraphobia), or aging (gerascophobia).

- Situational type – Fear of small confined spaces (claustrophobia), or the dark (nyctophobia).

- Blood/injection/injury type – this includes fear of medical procedures, including needles and injections (trypanophobia), fear of blood (hemophobia) and fear of getting injured.

- Other – children's fears of loud sounds or costumed characters.

Prevention of anxiety disorders is one focus of research. Use of CBT and related techniques may decrease the number of children with social anxiety disorder following completion of prevention programs.

Main features of diagnostic criteria for specific phobia in the DSM-IV-TR:

- Marked and persistent fear that is excessive or unreasonable, cued by the presence or anticipation of a specific object or situation (e.g., flying, heights, animals, receiving an injection, seeing blood).

- Exposure to the phobic stimulus almost invariably provokes an immediate anxiety response, which may take the form of a situationally bound or situationally predisposed panic attack. In children, the anxiety may be expressed by crying, tantrums, freezing, or clinging.

- The person recognizes that the fear is excessive or unreasonable. In children, this feature may be absent.

- The phobic situation(s) is avoided or else is endured with intense anxiety or distress.

Specific Phobia – DSM 5 Criteria

- Fear or anxiety about a specific object or situation (In children fear/anxiety can be expressed by crying, tantrums, freezing, or clinging)

- The phobic object or situation almost always provokes immediate fear or anxiety

- The phobic object or situation is avoided or endured with intense fear or anxiety

- The fear or anxiety is out of proportion to the actual danger posed by the specific object or situation and to the sociocultural context

- The fear, anxiety, or avoidance is persistent, typically lasting for 6 months or more

- The fear, anxiety, or avoidance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning

- The disturbance is not better explained by symptoms of another mental disorder, including fear, anxiety, and avoidance of situations associated with panic-like symptoms or other incapacitating symptoms; objects or situations related to obsessions; reminders of traumatic events; separation from home or attachment figures; or social situations

In the US, the American College of Obstetricians and Gynecologists suggests healthcare providers consider depression screening for perinatal women. Additionally, the American Academy of Pediatrics recommends pediatricians screen mothers for PPD at 1-month, 2-month and 4-month visits. However, many providers do not consistently provide screening and appropriate follow-up. For example, in Canada, Alberta is the only province with universal PPD screening. This screening is carried out by Public Health nurses with the baby's immunization schedule.

The Edinburgh Postnatal Depression Scale, a standardized self-reported questionnaire, may be used to identify women who have postpartum depression. If the new mother scores 13 or more, she likely has PPD and further assessment should follow.

Panic disorder typically begins during early adulthood; roughly half of all people who have panic disorder develop the condition before age 24, especially those subjected to traumatic experiences. However, some sources say that the majority of young people affected for the first time are between the ages of 25 and 30. Women are twice as likely as men to develop panic disorder and it occurs more often in people with above average intelligence.

Panic disorder can continue for months or years, depending on how and when treatment is sought. If left untreated, it may worsen to the point where one's life is seriously affected by panic attacks and by attempts to avoid or conceal the condition. In fact, many people have had problems with personal relationships or employment while struggling to cope with panic disorder. Some people with panic disorder may conceal their condition because of the stigma of mental illness. In some individuals, symptoms may occur frequently for a period of months or years, then many years may pass without symptoms. In some cases, the symptoms persist at the same level indefinitely. There is also some evidence that many individuals (especially those who develop symptoms at an early age) may experience symptom cessation later in life (e.g. past age 50).

In 2000, the World Health Organization found prevalence and incidence rates for panic disorder to be very similar across the globe. Age-standardized prevalence per 100,000 ranged from 309 in Africa to 330 in East Asia for men and from 613 in Africa to 649 in North America, Oceania, and Europe for women.

Many people being treated for panic attacks begin to experience limited symptom attacks. These panic attacks are less comprehensive, with fewer than four bodily symptoms being experienced.

It is not unusual to experience only one or two symptoms at a time, such as vibrations in their legs, shortness of breath, or an intense wave of heat traveling up their bodies, which is not similar to hot flashes due to estrogen shortage. Some symptoms, such as vibrations in the legs, are sufficiently different from any normal sensation that they clearly indicate panic disorder. Other symptoms on the list can occur in people who may or may not have panic disorder. Panic disorder does not require four or more symptoms to all be present at the same time. Causeless panic and racing heartbeat are sufficient to indicate a panic attack.

In the opinion of Allen Frances, chair of the DSM-IV task force, the DSM-5's somatic symptom disorder brings with it a risk of mislabeling a sizable proportion of the population as mentally ill. “Millions of people could be mislabeled, with the burden falling disproportionately on women, because they are more likely to be casually dismissed as ‘catastrophizers’ when presenting with physical symptoms.”

Anti-anxiety and antidepressant medication is commonly prescribed for treatment of social anxiety disorder. Selective serotonin reuptake inhibitors (SSRIs) such as sertraline, fluvoxamine and paroxetine are common medications which alleviate social phobia successfully in the short term but it is not certain if they are useful in the long-term. Also the MAOI moclobemide works well on treating social phobia in the short term. Patients who have avoided certain situations should make a big effort to become exposed to these situations while at the same time taking antidepressant medication. Anxiolytic medication aids a patient to handle social or professional situations before more lasting treatment has had an effect and therefore it is a provider of short term relief, but anxiolytics have a risk of dependence. Beta-adrenergic antagonists help to control palpitations and tremors unresponsive to the treatment of anxiolytic medication. One must read the precautions of these drugs outlined in the manufacturer's literature and be careful to watch out for the contraindications of these drugs.

Cognitive behavioral therapy (CBT) is commonly used to treat social phobia.

Somatic symptom disorder has been a controversial diagnosis, since it was historically based primarily on negative criteria - that is, the absence of a medical explanation for the presenting physical complaints. Consequently, any person suffering from a poorly understood illness can potentially fulfill the criteria for this psychiatric diagnosis, even if they exhibit no psychiatric symptoms in the conventional sense. In 2013-4, there were several widely publicized cases of individuals being involuntarily admitted to psychiatric wards on the basis of this diagnosis alone. This has raised concerns about the consequences of potential misuse of this diagnostic category.

There are two assessment tools used to diagnose emetophobia; the Specific Phobia of Vomiting inventory and the Emetophobia Questionnaire. The Specific Phobia of Vomiting Inventory and the Emetophobia Questionnaire are both self-report questionnaires that focus on a different range of symptoms.

There have been a limited number of studies in regard to emetophobia. Victims of the phobia usually experience fear before vomiting, but feel less afterwards. The fear comes again however, if the victim fears they will throw up again.

Agoraphobia occurs about twice as commonly among women as it does in men. The gender difference may be attributable to several factors: sociocultural traditions that encourage, or permit, the greater expression of avoidance coping strategies by women (including dependent and helpless behaviors), women perhaps being more likely to seek help and therefore be diagnosed, and men being more likely to abuse alcohol in reaction to anxiety and be diagnosed as an alcoholic. Research has not yet produced a single clear explanation for the gender difference in agoraphobia.

Panic disorder with or without agoraphobia affects roughly 5.1% of Americans, and about 1/3 of this population with panic disorder have comorbid agoraphobia. It is uncommon to have agoraphobia without panic attacks, with only 0.17% of people with agorophobia not presenting panic disorders as well.

There are several options for treatment of scopophobia. With one option, desensitization, the patient is stared at for a prolonged period and then describes their feelings. The hope is that the individual will either be desensitized to being stared at or will discover the root of their scopophobia.

Exposure therapy, another treatment commonly prescribed, has five steps:

- Evaluation

- Feedback

- Developing a fear hierarchy

- Exposure

- Building

In the evaluation stage, the scopophobic individual would describe their fear to the therapist and try to find out when and why this fear developed. The feedback stage is when the therapist offers a way of treating the phobia. A fear hierarchy is then developed, where the individual creates a list of scenarios involving their fear, with each one becoming worse and worse. Exposure involves the individual being exposed to the scenarios and situations in their fear hierarchy. Finally, building is when the patient, comfortable with one step, moves on to the next.

As with many human health problems support groups exist for scopophobic individuals. Being around other people who face the same issues can often create a more comfortable environment.

Other suggested treatments for scopophobia include hypnotherapy, neuro-linguistic programming (NLP), and energy psychology. In extreme cases of scopophobia, it is possible for the subject to be prescribed anti–anxiety medications. Medications may include benzodiazepines, antidepressants, or beta-blockers.