Because ADHD develops during childhood, the information presented here focuses on children. The primary symptoms of ADHD are inattention, hyperactivity, and impulsivity. At some time in their lives, all children are inattentive, hyperactive, or impulsive. However, children with ADHD have symptoms that are noticeably more severe and consistent. They have difficulty in school and with their family and peer relationships.

There are several different types of ADHD. Some children are mainly inattentive and don't display signs of hyperactivity (classic attention deficit disorder). However, some are hyperactive, some are impulsive, and others exhibit a mixture of these symptoms.

Behaviors linked to ADHD can last into adulthood, often resulting in problems with relationships and employment. Specific symptoms include:

  • Inattentive (classic ADD)
    • Easily distracted by sights and sounds
    • Doesn't pay attention to detail
    • Doesn't seem to listen when spoken to
    • Makes careless mistakes
    • Doesn't follow through on instructions or tasks
    • Avoids or dislikes activities that require longer periods of mental effort
    • Loses or forgets items necessary for tasks
    • Is forgetful in day-to-day activities
    • Has difficulty organizing tasks
    • Hyperfocuses on certain activities
    • Has difficulty with transitions
  • Hyperactive
    • Is restless, fidgets, and squirms
    • Runs and climbs and is not able to stay seated
    • Has difficulty playing quietly
    • Talks excessively
  • Impulsive
    • Blurts out answers before hearing the entire question
    • Interrupts others
    • Has difficulty waiting in line or waiting for turn
  • Combined (most common type)
    • Has a combination of the above symptoms

People with ADHD also can have: