The essential feature of Major Depressive Episode is that the symptom of either depressed mood or loss of interest in almost all activities needs to be present for a period of at least two weeks.
In children and adolescents, the mood may be irritable rather than sad.
An individual must also experience at least four additional symptoms from a list that includes:

• Changes in appetite or weight.
  
• Sleep and psychomotor activity.
  
• Decreased energy.
  
• Feelings of worthlessness or guilt.
  
• Difficulty concentrating or making decisions.
  
• Recurrent thoughts regarding or planning death.
  
• Suicidal ideation or attempts.
  

To a diagnosis to be made, the symptom of a Major Depressive Episode must either be present or have recently worsened clearly in comparison to the person's state before the episode.
The symptoms must persist for most of the day, nearly every day for at least two consecutive weeks.
The episode must be accompanied by feelings of sadness or clinically significant impairment in social, occupational or other important areas.
The mood in a Major Depressive Episode is often described by the person as depressed, sad, discouraging, hopeless or "down".
In some cases, grief may be initially denied, but can subsequently be reported during an interview assessment where a client usually cries.
In some individuals who complain of feelings of emptiness, without being emotional or anxious, the presence of depressive mood can be seen from facial expression and/or behavior.
Some sufferers complain of somatic symptoms such as body aches, instead of describing feelings of sadness.
Many clients describe, or show increased irritability as in:

• persistent anger.
  
• tendency to respond to events with outbursts of anger or blame others.
  
• an exaggerated sense of frustration regarding small events.
  

Loss of interest or pleasure is almost always present, even in a slight degree.
Individuals may describe feeling less interested in their hobbies, or cease to take pleasure in activities for which they used to show interest.
Family members often notice the social isolation or neglect in pleasant occupations.
In some patients, a reduction in levels of sexual desire and interest may occur.
Appetite is usually diminished and some individuals struggle to eat.
Others may have an increase of appetite or want some specific foods, e.
g.
sweets or other carbohydrates.
When changes in appetite are intense, in either direction, there may be an increase or significant weight loss or, in children, failing to achieve the expected increase in weight for their age.