BDD is characterized by an unusual degree of worry or concern about a specific part of the face or body, rather than the general size or shape of the body. It is distinguished from anorexia nervosa and bulimia nervosa in that patients with eating disorders are preoccupied with their overall weight and body shape. As many as 50 percent of patients diagnosed with BDD undergo plastic surgery to correct their perceived physical defects.

Since the publication of DSM-IV in 1994, some psychiatrists have suggested that there is a subtype of BDD, namely muscle dysmorphia. Muscle dysmorphia is marked by excessive concern with one's muscularity and/or fitness. Persons with muscle dysmorphia spend unusual amounts of time working out in gyms or exercising rather than dieting obsessively or seeking plastic surgery. DSM-IV-TR added references to concern about body build and excessive weight lifting to DSM-IV's description of BDD in order to cover muscle dysmorphia.

BDD and muscle dysmorphia can both be described as disorders resulting from the patient's distorted body image. Body image refers to a person's mental picture of his or her outward appearance, including size, shape, and form. It has two major components: how the person perceives their physical appearance, and how they feel about their body. Significant distortions in self-perception can lead to intense dissatisfaction with one's body and dysfunctional behaviors aimed at improving one's appearance. Some patients with BDD are aware that their concerns are excessive, but others do not have this degree of insight; about 50 percent of patients diagnosed with BDD also meet the criteria for a delusional disorder.

The usual age of onset of BDD is late childhood or early adolescence; the average age of patients diagnosed with the disorder is 17. BDD has a high rate of comorbidity, which means that people diagnosed with the disorder are highly likely to have been diagnosed with another psychiatric disorder— most commonly major depression, social phobia, or obsessive-compulsive disorder (OCD). About 29% of patients with BDD eventually try to commit suicide.

BDD is thought to affect 1–2 percent of the general population in the United States and Canada, although some doctors think that it is underdiagnosed because it coexists so often with depression and other disorders. In addition, patients are often ashamed of grooming rituals and other behaviors associated with BDD, and may avoid telling their doctor about them. BDD is thought to affect men and women equally; however, there are no reliable data as of the early 2000s regarding racial or ethnic differences in the incidence of the disorder.

The causes of BDD fall into two major categories, neurobiological and psychosocial.

Research indicates that patients diagnosed with BDD have serotonin levels that are lower than normal. Serotonin is a neurotransmitter— a chemical produced by the brain that helps to transmit nerve impulses across the junctions between nerve cells. Low serotonin levels are associated with depression and other mood disorders.

Another important factor in the development of BDD is the influence of the mass media in developed countries, particularly the role of advertising in spreading images of physically “perfect” men and women. Impressionable children and adolescents absorb the message that anything short of physical perfection is unacceptable. They may then develop distorted perceptions of their own faces and bodies.

A young person's family of origin also has a powerful influence on his or her vulnerability to BDD. Children whose parents are themselves obsessed with appearance, dieting, and/or body building, or who are highly critical of their children's looks, are at greater risk of developing BDD.

An additional factor in some young people is a history of childhood trauma or abuse. Buried feelings about the abuse or traumatic incident may emerge in the form of obsession about a part of the face or body. This “reassignment” of emotions from the unacknowledged true cause to another issue is called displacement. For example, an adolescent who frequently felt overwhelmed in childhood by physically abusive parents may develop a preoccupation at the high school level with muscular strength and power.

The central symptom of BDD is excessive concern with a specific facial feature or body part. Research indicates that the features most likely to be the focus of the patient's attention are (in order of frequency) complexion flaws (acne, blemishes, scars, wrinkles); hair (on the head or the body, too much or too little); and facial features (size, shape, or lack of symmetry). The patient's concerns may, however, involve other body parts, and may shift over time from one feature to another.

Other symptoms of body dysmorphic disorder include:

• Ritualistic behavior. Ritualistic behavior refers to actions that the patient performs to manage anxiety and that take up excessive amounts of his or her time. Patients are typically upset if someone or something interferes with or interrupts their ritual. Ritualistic behaviors in BDD may include exercise or makeup routines, assuming specific poses or postures in front of a mirror, etc.
• Camouflaging the “problem” feature or body part with makeup, hats, or clothing. Camouflaging appears to be the single most common symptom among patients with BDD; it is reported by 94%.
• Abnormal behavior around mirrors, car bumpers, large windows, or similar reflecting surfaces. A majority of patients diagnosed with BDD frequently check their appearance in mirrors or spend long periods of time doing so. A minority, however, react in the opposite fashion and avoid mirrors whenever possible.
• Frequent requests for reassurance from others about their appearance.
• Frequently comparing one's appearance to others.
• Avoiding activities outside the home, including school and social events.

The diagnosis of BDD in children or adolescents is often made by physicians in family practice because they are more likely to have developed long-term relationships of trust with young people. At the adult level, it is often specialists in dermatology, cosmetic dentistry, or plastic surgery who may suspect that the patient suffers from BDD because of frequent requests for repeated or unnecessary procedures. Reported rates of BDD among dermatology and cosmetic surgery patients range between 6 and 15 percent. The diagnosis is made on the basis of the patient's history together with the physician's observations of the patient's overall mood and conversation patterns. People with BDD often come across to others as generally anxious and worried. In addition, the patient's dress or clothing styles may suggest a diagnosis of BDD. It is not unusual, however, for patients with BDD to take offense if their primary care doctor suggests referral to a psychiatrist.

Some physicians may use a self-report questionnaire, such as the Multidimensional Body-Self Relations Questionnaire (MBSRQ) or the short form of the Situational Inventory of Body-Image Dysphoria (SIBID), to evaluate patients during an office visit.

There are no brain imaging studies or laboratory tests as of the early 2000s that can be used to diagnose BDD.

The standard course of treatment for body dysmorphic disorder is a combination of medications and psychotherapy. Surgical, dental, or dermatologic treatments have been found to be ineffective.

The medications most frequently prescribed for patients with BDD are the selective serotonin reuptake inhibitors, most commonly fluoxetine (Prozac) or sertraline (Zoloft). Other SSRIs that have been used with this group of patients include fluvoxamine (Luvox) and paroxetine (Paxil). In fact, it is the relatively high rate of positive responses to SSRIs among BDD patients that led to the hypothesis that the disorder has a neurobiological component related to serotonin levels in the body. An associated finding is that patients with BDD require higher dosages of SSRI medications than patients who are being treated for depression with these drugs.

The most effective approach to psychotherapy with BDD patients is cognitive-behavioral restructuring. Since the disorder is related to delusions about one's appearance, cognitive-oriented therapy that challenges inaccurate self-perceptions is more effective than purely supportive approaches. Thought-stopping and relaxation techniques also work well with BDD patients when they are combined with cognitive restructuring.

Some doctors recommend couples therapy or family therapy in order to involve the patient’s parents, spouse, or partner in his or her treatment. This approach may be particularly helpful if family members are critical of the patient’s looks or are reinforcing his or her unrealistic body image.

Although no alternative or complementary form of treatment has been recommended specifically for BDD, such herbal remedies for depression as St. John's wort have been reported as helping some BDD patients. Aromatherapy appears to be a useful aid to relaxation techniques as well as a pleasurable physical experience for BDD patients. Yoga has helped some persons with BDD acquire more realistic perceptions of their bodies and to replace obsessions about external appearance with new respect for their body's inner structure and functioning.

As of early 2005, the prognosis of BDD is considered good for patients receiving appropriate treatment. On the other hand, researchers do not know enough about the lifetime course of body dysmorphic disorder to offer detailed statistics. DSM-IV-TR notes that the disorder “has a fairly continuous course, with few symptom-free intervals, although the intensity of symptoms may wax and wane over time.”

Given the pervasive influence of the mass media in contemporary Western societies, the best preventive strategy involves challenging their unrealistic images of attractive people. Parents, teachers, primary health care professionals, and other adults who work with young people can point out and discuss the pitfalls of trying to look “perfect.” In addition, parents or other adults can educate themselves about BDD and its symptoms, and pay attention to any warning signs in their children's dress or behavior.