Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that affects attention, impulse control, activity level and executive functioning. It begins in childhood, although some people are not diagnosed until adolescence or adulthood.
Common signs
ADHD symptoms fall into two main groups: inattention and hyperactivity or impulsivity. A person may mainly have inattentive symptoms, mainly hyperactive-impulsive symptoms, or a combination.
- Difficulty sustaining attention or finishing tasks
- Frequently losing items or forgetting responsibilities
- Difficulty organizing time and activities
- Being easily distracted
- Restlessness or difficulty remaining seated when expected
- Talking excessively or interrupting
- Difficulty waiting for a turn
- Acting quickly without considering consequences
Everyone experiences some of these behaviors at times. ADHD is considered when symptoms are persistent, began during childhood, occur in more than one setting and interfere with everyday functioning.
ADHD in children
Symptoms may affect schoolwork, friendships, family routines and behavior. Girls and children with predominantly inattentive symptoms can be overlooked because they may show less obvious hyperactivity. Assessment should consider development, learning, sleep, anxiety, autism and other conditions that can resemble or occur alongside ADHD.
ADHD in adults
Adults may experience disorganization, procrastination, poor time management, forgetfulness, impulsive decisions, restlessness and difficulty completing tasks. Symptoms can affect work, education, finances, driving and relationships.
Diagnosis
There is no single blood test, brain scan or online questionnaire that can diagnose ADHD. A qualified clinician uses a comprehensive assessment that includes developmental and medical history, current symptoms, their impact on daily life and information from relevant settings. Other possible explanations for symptoms should also be considered.
Treatment and support
Treatment is individualized and may include education about ADHD, behavioral strategies, organizational support, parent training, school or workplace accommodations, psychological treatment and medication. Stimulant and nonstimulant medications can be effective for appropriate patients but require professional assessment, prescribing and follow-up.
Regular physical activity, consistent sleep routines and practical systems such as calendars, reminders and breaking large tasks into smaller steps can support day-to-day functioning. These strategies complement rather than replace evidence-based treatment when treatment is needed.
When to seek help
Consider professional assessment when attention, impulsivity or activity-level difficulties are persistent and interfere with school, work, relationships or daily responsibilities. Seek prompt mental health support if ADHD occurs with severe depression, substance misuse, dangerous impulsive behavior or thoughts of self-harm.
This information is general and does not replace individual medical or mental health assessment or treatment.
Sources and further reading
Last reviewed: 28 September 2026.