Hwabyung patients reported that they were beaten and mistreated by their husbands or were in constant conflict with their in-laws (30, 31, 33). Although they had worked hard and performed their best for their families, they were not rewarded. Thus, they felt victimized and mortified (30). In some cases, Hwabyung patients were bullied by neighbors, so they felt lonely and unjust (31).

Hwabyung patients try to communicate with their husbands but fail and eventually stop trying (32, 33, 36). Whenever they would make a claim, the husband would insult them or harshly refute the claim (32, 33). Some patients reported that their relationships with their spouses lacked understanding and affection, and that there was no communication between them (33). There have also been reports of husbands having extramarital affairs. The patients condemned their husbands for the affairs because they had not rejected their husbands sexually (33).

Most Hwabyung patients encounter overwhelming life obstacles, such as poverty (30, 31, 33). Sometimes, the patients, instead of their husbands, were responsible for earning money (30). Because of these hardships, they felt tired and unhappy (30, 31).

Some Hwabyung patients experienced frustration over disappointments regarding their children. For example, their children's academic or career failures would upset them. Besides disappointment, heartbreak over their children's illnesses also causes emotional suffering (32).

Hwabyung patients reported that stressful life events frequently provoked anger (32, 34, 36).

Hwabyung patients had the desire to escape from reality, but they did not (33). There were two main reasons why these patients persevered: First, many believed their destinies were inevitable and that it was their duty to uphold the values of their culture (30, 32). Although the main cause of stress for many of the patients was their husbands, they had a compulsory tendency to follow Korea's patriarchal system (31). They believed that they were unable to change their situation or society, so they obeyed their husbands and maintained their families instead of getting divorced (30). Second, one of the primary goals was to raise their children well. Therefore, they sacrificed their own happiness for their children. They devoted themselves to their children and suppressed their anger, even to the point of illness (32).

Hwabyung patients had negative thought patterns, such as rumination and personalization. The patients repeatedly focused on the same thoughts related to the past. These thoughts usually trigger negative emotions and other or self-blame (34, 36). In some cases, the patient had an irrational belief that all her bad experiences were her own fault (31).

Hwabyung patients experienced various negative emotions (30, 32, 33), including anger and nervousness (30, 31, 33). When the patients looked back on their lives, they expressed more complex emotions, such as regret, a sense of nihility, deep sorrow or grief (“Haan”), and painful feelings, such as burning in the soul (30–33).

Hwabyung patients engage in inappropriate behaviors that weaken their interpersonal relationships (particularly with their spouses or neighbors) (31, 32, 35). Some patients neglect their self-care and withdraw from social activities (31). Other patients ignored their husbands out of revenge (believing that the husband had not treated them fairly) or to avoid conflicts (32, 35).

Patients with Hwabyung reported physical and psychological symptoms. The patients experienced physical symptoms, such as heat sensations, palpitations, and chest tightness. They also found it difficult to block excessive emotions and negative thoughts (30–32, 34). They appeared unstable and imperfect (31). During the recovery process, they are still sensitive and irritable to stimuli (34).

Most Hwabyung patients either expressed their anger through emotional outbursts or suppressed it, and they had difficulty changing this pattern and regulating their emotions. The manner in which anger was expressed seemed to be linked to personality traits (30, 31, 36).

The patient's perspective on recovery from the disorder was affected by the extent to which they blamed the external environment and their attitude toward self-regulation. Patients who thought the effects of external stress were absolute seemed to show a passive and pessimistic attitude. On the other hand, patients who thought self-regulation was important showed a relatively active attitude. However, they also had the limitation of avoiding direct problem-solving (34, 36). Patients demonstrated different expectations regarding professional help, especially psychotherapy, based on their willingness to change. Some looked forward to the effects of counseling, but others thought that Hwabyung had no therapeutic options, or that treatment was useless because symptoms recurred even after counseling sessions (36). Overall, the patients were less confident about controllability.

Specific active coping strategies differed according to the source of distress. For example, Hwabyung patients who suffered from domestic abuse divorced their husbands. Some have sought new solutions to resolve their conflicts. Patients who needed to make life changes took on this responsibility and worked hard to improve their situations and, consequently, their symptoms (31, 32, 34, 35).

Distancing is an emotion-focused coping strategy. Hwabyung patients commonly used distancing as a coping strategy because they believed that nothing could be done to improve their symptoms (31, 32, 34).

Support coping includes all efforts to seek emotional and instrumental support (41). Hwabyung patients experienced improvement when they received support, encouragement, and comfort from family, friends, or neighbors. It was also found that taking medication or seeing a doctor was helpful in relieving symptoms (32, 34–36).

Positive cognitive restructuring is a meaning-focused strategy. Some Hwabyung patients focused on the positive aspects of their lives and themselves (31, 32). Some developed new hopes or goals (32, 35) or chose to undergo a process of loving kindness (e.g., understanding, acceptance, and forgiveness) (32–34). In other cases, they found support through religion (32).

Patients who recovered from Hwabyung recognized improvements in various aspects of their lives. Physical symptoms decreased. Emotions can be regulated and stabilized, even when patients are confronted with the same stressors experienced before recovery. Negative thoughts turned into positive. Interpersonal conflicts subsided, and the relationships improved (34).

According to earlier studies, women are more vulnerable to Hwabyung than men. The prevalence of Hwabyung in females was almost 2.5 or 3 times higher than in males (males: 2.1–2.5% and females: 5.6–7.5%) (11, 14). As with other mental disorders, including depression and anxiety disorders, reasons for gender differences in the prevalence of Hwabyung are not yet clear. Potential underlying biological factors are sex differences in hypothalamic-pituitary-adrenal (HPA) axis responses to stress (56), reproductive hormones (57), neuro-immune system (58) brain structure and function (59), and epigenetic environment (60).

At the same time, women' s social vulnerability of women exists in a cultural context (61). As cultures influence individual's beliefs, values, and behavioral patterns, Hwabyung has been considered a specific syndrome found in Koreans or Korean immigrants (4, 9, 21, 25, 31, 62–64). In Korea, which has a collectivistic and patriarchal society, women are particularly vulnerable to an unfair treatment, including domestic abuse and being forced to sacrifice for their families, especially their children. Nevertheless, Korean women believe that taking care of their families and raising children well is a task given to them as members of society. The self-esteem of Korean women depends on their children (65).

However, notably, from the perspective of female Hwabyung patients, the low marital satisfaction, a risk factor for Hwabyung, is significantly related to the husband's unfair attitude toward the role of women rather than the perception of the wife's gender role (61). This conclusion suggests that the spouses' attitudes are a more critical factor in the development of Hwabyung than the internalized cultural values of the patients.

In summary, we believe that both genetic and environmental influences are correlated to vulnerability of women to Hwabyung. Although Hwabyung was only investigated in Korea, we believe that these underlying experiences may extend beyond Korean culture, because this review focused on individuals' psychological experiences. Because these assumptions are not yet supported by empirical evidence, further studies on Hwabyung will be required to investigate the distinction between emic and etic manifestations of Hwabyung.

Horowitz (66) argued that stress reactions, such as grief, adjustment disorder, and posttraumatic stress disorder, correspond to stress response syndromes. However, Simmen-Janevska and Maercker (67) proposed a model of normal and pathological stress reactions by modifying the Horowitz stress-response model (68). They differentiated pathological symptoms, dysfunctional behavior (e.g., abusing tranquillisers), and preoccupations, from normal responses such as alternating suppression/denial and intrusions. A normal stress response usually results in adaptation and relative completion, while a pathological consequence is a mental disorder or personality change. In other words, what Simmen-Janevska and Maercker's model (67) implies is that the difference between “adaptive” and “pathologic” response is the intensity of distress applied to life.

Bonanno (69) described four trajectories of potentially traumatic events (e.g., loss and trauma): chronic, delayed, recovery, and resilience. A recent review of trajectory models (55) has provided evidence that various consequences appear after traumatic stress. According to the review, most people maintain or recover their mental health even after a traumatic event. In contrast, a small percentage of people progress chronically (delayed onset in 8.9% of the population and chronicity in 10.6%). Although resilience is a natural response to traumatic events and occurs in the majority of those who have suffered such an event, people use various coping strategies and have different outcomes. Therefore, we need to go beyond the dichotomy of normal and abnormal and investigate the details of adaptation processes and mechanisms (69).

At the beginning of Hwabyung research, a survey of Korean psychiatrists and doctors of traditional Korean medicine revealed that the general population considered Hwabyung synonymous with “neurotic” or “stress” related conditions (70). However, during the next two decades, the experts gradually distinguished Hwabyung from stress response and established it as a mental disorder because it presented distinct emotional and physical symptoms and the patients complained of serious distress (25).

Several empirical studies have likewise indicated that the severity of psychiatric symptoms in Hwabyung is clinically meaningful. A previous cross-sectional study (18) reported mean scores of Center for Epidemiologic Studies Depression (CES-D) scale in Hwabyung group (n = 92) was 31.98 points, which indicated clinical depression. Additionally, state anger scores of STAXI in Hwabyung group were significantly higher (16.71 points) than that of non-Hwabyung group (13.43 points). A recent study (71) also found that Hwabyung patients (n = 58) scored significantly higher for depression, anger, hostility, and aggression than patients with clinical depression (n = 180). Another study (72) reported slightly different results, but this inconsistency may be due to small samples of Hwabyung group; the mean scores of STAXI were significantly higher in Hwabyung group (n = 6) than in the non-Hwabyung group (n = 283), 52.83 points vs. 39.8 points, but there was no significant difference in depression scores between the two groups.

We believe that the consequence (i.e., severity and chronicity of symptoms) determines whether a response to stress is pathological or adaptive. Therefore, we consider Hwabyung to be a mental disorder rather than an adaptive response.

In the DSM-5 (73), two diagnoses mainly focus on recurrent aggressive outbursts: intermittent explosive disorder (IED) and disruptive mood dysregulation disorder (DMDD). IED and DMDD share core features (temper outbursts and behavioral outbursts), but there are some differences. For instance, IED is characterized by behavioral outbursts that occur twice weekly, whereas DMDD comprises three or more temper outbursts per week and persistent irritability or anger, which begins in adolescence (with patients under 10 years of age) and cannot be diagnosed for the first time in adults (over 18 years). The persistent anger present in DMDD is diagnostically and clinically the most important difference between IED and DMDD. That is, IED patients spend less time in an angry state between behavioral outbursts (74). According to DSM-5 (73), the risk factors of IED include a history of physical and emotional trauma, serotonergic abnormalities, and amygdala hyperactivity to anger stimuli, while those of DMDD involve temperament and deficits in information processing and attention to emotional stimuli.

Compared to IED and DMDD, anger in the major diagnostic criteria of Hwabyung is inner experience (i.e., feeling of unfairness and subjective anger) and not aggression (19). Although this review included the subthemes of “tantrum” (31), “quick-tempered personality” (30), “volatile type,” and “volatile personality traits” (36), these indicate part of a complex of emotions, and are kinds of specifiers. The synthesized finding of “blame” indicates that Hwabyung patients experience various emotions as well as anger, and that this involves inward or passive aggression, rather than behavioral outbursts. Another synthesized finding of “uncontrollable physical and emotional symptoms” addresses the outcome that Hwabyung causes not only psychological but also physical symptoms. Physical symptoms, such as respiratory stuffiness, heat sensation, feeling of something pushing up, and epigastric mass, are extensively emphasized in the diagnostic criteria of Hwabyung (19). Moreover, in terms of etiology and risk factors, Hwabyung symptoms develop and progress during or after extremely stressful events, such as domestic violence or financial problems, in which anger may have been suppressed, so the onset of Hwabyung frequently occurs in middle-aged or later life (18). The synthesized finding of “anger arousal” also showed that anger triggers in Hwabyung were not episodic but long-term stressors, unlike in IED and DMDD.

As mentioned in the introduction, Asians commonly suppress their emotions. Several papers (75–77) have suggested that Asians complain more about physical symptoms than psychological symptoms in mental disorders. Thus, many researchers have considered Hwabyung to be a subtype of depression in Korea (78–80). Some researchers have described that anger and depression appear sequentially in the progression of Hwabyung, such as in a cyclothymic disorder (81). Although there are differences between these studies, depression, including major depressive disorder (MDD) and dysthymic disorder, was found in 30.5–37.5% of Hwabyung patients (18, 82). In one study (83), 60.7% of Hwabyung patients had underlying MDD. Despite the high comorbidity, the two are not exactly the same, and one is not completely included in the other.

Compared to depression, Hwabyung is more somatic, hyperarousal, and severe with regard to anger (71, 84). Hwabyung researchers have paid attention to its distinctive physical symptoms and typical causes, as well as anger, in order to distinguish between Hwabyung and depression (39, 85–87). The physical symptoms of Hwabyung include respiratory stuffiness, a heat sensation, a feeling of pushing up in the chest, a feeling of a mass in the throat or epigastrium, dry mouth, headache or dizziness, palpitations, and sighing (19). These symptoms are well clustered in this syndrome. Another difference between Hwabyung and MDD is that Hwabyung must be preceded by a stressful event, and these events are typically related to family, close neighborhoods, or financial problems (see synthesized finding “anger arousal”). The patient resents and blames a particular object or situation (see the synthesized finding “blame”), whereas MDD patients feel guilty. It should also be noted that Hwabyung's diagnostic criteria do not include suicidal ideation (19).

Lastly, we should compare Hwabyung and adjustment disorder. According to DSM-5 (73), adjustment disorder is defined as the presence of emotional or behavioral symptoms in response to one or more identifiable stressors. In adjustment disorders, symptoms develop and then disappear in the short-term depending on the onset and end of the stressor. However, unlike adjustment disorder, Hwabyung symptoms last after the stressor or its consequences are terminated. As shown in the results of meta-aggregation, Hwabyung patients stated that they could not improve because they still remembered stressful events (34, 36). It has been consistently reported that persistent and aggravating factors of Hwabyung are not only stressors but also rumination of bad memories (88) and blame (51).

Hwabyung has been proposed as a new anger disorder, but it is currently not reflected in the DSM-5 (73). Min, a Korean psychiatrist, has consistently suggested that Hwabyung could offer the opportunity for the formulation of a new model of pathological anger (89) and proposed an anger disorder in 2008 (16). Following this proposal, we agree on the need for a new anger disorder in official classification systems such as the DSM and ICD.

Explosive and aggressive outbursts are not the only anger-related mental problems, and various anger-related symptoms or syndromes have been reported. For instance, Fava (90) first reported anger attacks in patients with MDD in 1990. Anger attacks are associated with persistent irritability in patients with MDD (91). Linden (92–94) introduced posttraumatic embitterment disorder (PTED) as a new subtype of adjustment disorder in 2003. PTED could occur because of negative life events, to which the patient with PTED experiences embitterment, rage, and helplessness, and reacts with emotional arousal. The characteristic symptoms of PTED are repeated intrusive memories and persistent negative changes in one's mental well-being. In addition, Ataques de Nervios (of Mexico) and Stagnation Syndrome (of China) also share some characteristics of Hwabyung, such as suppression and affective dysregulation. The experience of Hwabyung's “uncontrollable physical and emotional symptoms” is very similar to the core feature of Ataques de Nervios in Puerto Rico. A study exploring Ataques de Nervios also identified that patients experienced “loss of control” of their emotional expression, bodily sensations, behavior, and nervous system due to psychological shock during the illness period (95). On the other hand, Stagnation Syndrome is defined as “a general term for diseased states characterized by a depressed mood with feelings of despair or uneasiness” in the International Standard Terminologies on Traditional Medicine by the World Health Organization (96). Stagnation Syndrome includes depression, restlessness, emotional changes, lack of energy, frequent sighing, and poor appetite (97, 98). Leng et al. (99, 100) suggested that Stagnation Syndrome was related to MDD and functional somatic syndrome, because Stagnation Syndrome showed various bodily symptoms and psychological problems.

All of these reports have indicated that there are patients with persistent negative emotions and intermittent anger attacks, but without explosive and aggressive outbursts. It is necessary to explore the aspects of anger disorder caused by the suppression of anger in a variety of contexts and cultures, and to reconcile the findings to suggest a new concept of mental disorder. Research into various anger disorders, including Hwabyung, will help complement the current mental health system.