ADHD symptoms fall into three groups: inattention, hyperactivity and impulsivity. Everyone shows some of these behaviours from time to time. ADHD is diagnosed when they are persistent, started in childhood, and get in the way of everyday life at school, at work, at home or in relationships. This guide explains the symptoms of ADHD in adults and children, how they can look different in women and girls, and what to do if you recognise them in yourself or your child.
ADHD symptoms checklist
Clinicians in the UK assess ADHD against two lists of symptoms, nine for inattention and nine for hyperactivity and impulsivity. Adults need five or more from a list, and children six or more, present for at least six months and across more than one setting. Use this checklist as a starting point rather than a diagnosis. Our free online ADHD test takes about five minutes if you want a more structured screen.
Inattentive symptoms of ADHD
- Making careless mistakes or overlooking details at work or school
- Difficulty keeping attention on tasks, conversations or reading
- Seeming not to listen when spoken to directly
- Starting tasks but not finishing them, or not following instructions through
- Trouble organising tasks, time and belongings
- Avoiding or putting off tasks that need sustained mental effort
- Losing things needed for daily life: keys, phone, paperwork, glasses
- Being easily distracted by surroundings or by your own thoughts
- Forgetfulness in daily activities such as appointments, bills and errands
Hyperactive and impulsive symptoms of ADHD
- Fidgeting, tapping hands or feet, or squirming in your seat
- Leaving your seat when you are expected to stay put
- Running or climbing in children; a strong inner restlessness in adults
- Difficulty doing anything quietly
- Feeling “on the go” or driven by a motor
- Talking excessively
- Blurting out answers before a question is finished
- Difficulty waiting your turn or queuing
- Interrupting or intruding on others’ conversations and activities
Which list dominates decides the presentation: predominantly inattentive, predominantly hyperactive-impulsive, or combined. You can read more about how these differ in our guide to the three types of ADHD.
Understanding ADHD
Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental condition that affects an estimated 3 to 5% of children and 2 to 3% of adults, according to the NHS England Independent ADHD Taskforce. It changes how the brain manages attention, activity and self-control, and it runs in families. The core difficulty is with executive function: the mental processes that let us plan, organise, hold information in mind, manage time and regulate our emotions. When these processes work less efficiently, everyday tasks such as finishing homework, keeping on top of admin or following through on plans take far more effort than they should.
ADHD is not a lack of willpower or a character flaw, and it is not caused by poor parenting, screens or diet. Research points to a combination of genetics and differences in how the brain uses dopamine and noradrenaline. It is also one of the most treatable conditions in mental health. With an accurate ADHD diagnosis and the right support, most people see a marked improvement in their symptoms and their quality of life.
Inattention: what it looks like day to day
Inattention is the most common ADHD symptom and is present in almost every diagnosis, whichever presentation someone has. It is not an inability to pay attention. People with ADHD can concentrate intensely on things that interest them, sometimes to the point of losing track of time. The difficulty is directing and sustaining attention on demand, particularly for tasks that are routine, lengthy or dull.
At work this shows up as missed details, unmet deadlines, unread emails and a to-do list that never gets shorter. It can stall careers: adults with ADHD are more likely to be made redundant, to change jobs frequently and to resign impulsively, which is why we cover the effects of untreated ADHD in adults in its own guide. At home it looks like unopened post, missed appointments and a running sense of being behind. At school it appears as daydreaming, incomplete homework and careless mistakes in work the child understands perfectly well. Our guide to inattentive ADHD in children explains why these children are often missed.
Hyperactivity: more than being unable to sit still
Hyperactivity is the symptom most people picture when they think of ADHD, but it changes a great deal with age. In young children it is physical: running, climbing, leaving their seat, never seeming to tire. By the teenage years it usually settles into fidgeting, restlessness and constant talking. In adults it is often almost invisible from the outside and felt as an inner motor: a mind that will not switch off, difficulty relaxing, trouble sleeping, and a need to keep busy.
At work hyperactivity can look like an inability to sit through long meetings, pacing while on calls or taking on too many projects at once. At home it can mean finding it hard to wind down in the evening or to sit and watch a film with the family. In the classroom it disrupts learning for the child and for others, and is the reason hyperactive children are diagnosed earlier and more often than inattentive ones.
Impulsivity: acting before thinking
Impulsivity means acting on an urge before the consequences have been weighed up. It appears across all presentations of ADHD. Common examples include interrupting, finishing other people’s sentences, blurting out remarks that cause offence, impulse spending, risky driving, quitting jobs or relationships on the spot, and difficulty waiting for anything.
Impulsivity is closely tied to emotional regulation. Many people with ADHD experience emotions more quickly and more intensely than others, with sudden frustration, a quick temper, or an acute sensitivity to criticism and perceived rejection. These are not on the official diagnostic list but they are among the symptoms people find hardest to live with, and we look at them in detail in our guides to ADHD and emotional dysregulation and rejection sensitive dysphoria.
Symptoms of ADHD in adults
ADHD does not start in adulthood, but it is often first recognised there. Many adults were never assessed as children, particularly those who were bright, quiet, or good at masking, and only realise what has been going on when a child is diagnosed, when the structure of school or a job falls away, or when the demands of adult life outstrip their coping strategies.
The symptoms of adult ADHD are the same three groups, but they present differently. Adults with ADHD commonly describe:
- Restlessness and an inability to relax, rather than visible hyperactivity
- Chronic disorganisation: missed deadlines, late bills, lost paperwork, a chaotic home or desk
- Trouble concentrating on and completing tasks, alongside intense focus on things they enjoy
- Poor time management, lateness and underestimating how long things take
- Impulsive decisions around money, relationships and work
- Mood swings, a short fuse and a low tolerance for frustration
- Difficulty coping with stress, and feeling overwhelmed by ordinary admin
- Unstable relationships, often linked to forgetfulness, interrupting and appearing not to listen
- A long history of underachieving relative to ability, and low self-esteem as a result
Adult ADHD frequently sits alongside anxiety, depression or sleep problems, and some of its symptoms overlap with theirs, which is one reason it goes unrecognised. Because there is no single test for ADHD, an assessment by a Consultant Psychiatrist who specialises in ADHD is the only reliable way to tell them apart. If this list feels familiar, our page on Adult ADHD Assessments explains what the process involves, and our guides to ADHD in men and the lesser-known signs of ADHD cover the symptoms people rarely connect to the condition.
Symptoms of ADHD in children
In children, ADHD symptoms are usually noticed first at school, where the demands on attention and self-control are highest. Signs are typically present before the age of 12, although many children are not assessed until later. Parents and teachers often describe a child who:
- Cannot stay seated during lessons or meals
- Talks constantly and interrupts
- Struggles to follow multi-step instructions
- Loses homework, PE kit and lunchboxes
- Makes careless mistakes despite understanding the work
- Has big emotional reactions to small setbacks
- Finds it hard to wait, take turns or play quietly
Some ADHD behaviours are ordinary for a child’s age. What matters is whether they are more frequent and more severe than in other children of the same age, and whether they cause real problems at school and at home. Our ADHD symptoms in children checklist is written for parents, and our guide to the nine symptoms of ADHD in children goes through each one with examples. If you are worried, our children’s ADHD clinic can assess children from the age of six.
How ADHD symptoms differ in women and girls
ADHD in women and girls is under-diagnosed because it tends to be inattentive rather than hyperactive, and because girls are often better at masking. Instead of a disruptive child, teachers see a daydreamer who is quiet, anxious and trying hard. In adulthood, symptoms are often put down to stress, anxiety or personality: chronic overwhelm, perfectionism that hides disorganisation, emotional sensitivity, and exhaustion from holding everything together. Hormonal changes across the menstrual cycle, pregnancy and the menopause can also make ADHD symptoms noticeably worse.
We cover this in depth in our guides to the common symptoms of ADD and ADHD in women and the signs of ADHD in girls, and on our ADHD for women page.
ADD and inattentive ADHD symptoms
ADD (attention deficit disorder) is the older name for what is now called predominantly inattentive ADHD. The term was dropped from the diagnostic manuals in the 1990s, but many people still use it, particularly for people with attention difficulties and no obvious hyperactivity. If you are looking for “ADD symptoms”, you are looking for the inattentive list above: difficulty sustaining attention, disorganisation, forgetfulness, losing things, distractibility and avoiding effortful tasks.
Inattentive ADHD is the presentation most likely to be missed, because the symptoms are internal and do not disturb anyone else. It is also the most common presentation in adults and in women. We explain the terminology in more detail in our article on the difference between ADD and ADHD.
What to do if you recognise these symptoms
Recognising the symptoms is the first step; the next is a proper assessment. At The ADHD Centre, assessments are carried out by a Consultant Psychiatrist and follow NICE guidelines. They involve a structured clinical interview, standardised rating scales and a review of your history, and they rule out or identify other conditions that can look like ADHD. You will leave with a clear answer and, if ADHD is diagnosed, a treatment plan.
Treatment usually combines ADHD medication with practical support such as coaching, cognitive behavioural therapy and adjustments at school or work. Medication is effective for most people and is reviewed regularly. Lifestyle factors including sleep, exercise and routine make a real difference too. You can read more about the options on our ADHD treatment page.
Frequently asked questions about ADHD symptoms
What are the three main symptoms of ADHD?
The three core symptoms are inattention, hyperactivity and impulsivity. Clinicians group them into two lists, inattentive and hyperactive-impulsive, and diagnose a predominantly inattentive, predominantly hyperactive-impulsive or combined presentation depending on which symptoms are present.
What are the signs of ADHD in adults?
Common signs include restlessness, disorganisation, difficulty concentrating and finishing tasks, poor time management, impulsive decisions, mood swings and unstable relationships. Adults rarely show the physical hyperactivity seen in children; instead they describe an inner restlessness and a mind that will not switch off.
Can you have ADHD without hyperactivity?
Yes. Predominantly inattentive ADHD, sometimes still called ADD, involves attention, organisation and memory difficulties without significant hyperactivity. It is the most common presentation in adults and in women, and the one most often missed in childhood.
How are ADHD symptoms different in women?
Women and girls are more likely to have inattentive symptoms and to mask them, so they are often described as dreamy, anxious or overwhelmed rather than disruptive. Symptoms can also fluctuate with hormonal changes across the menstrual cycle, pregnancy and the menopause.
At what age do ADHD symptoms start?
Symptoms are present before the age of 12 by definition, and often noticeable from around the age of three to six. They do not begin in adulthood, but they are frequently first recognised there.
How many symptoms do you need for an ADHD diagnosis?
Under the DSM-5 criteria used in the UK, children need six or more symptoms from either list and adults need five or more, present for at least six months, in two or more settings, with clear evidence they interfere with daily life.
Is there a test for ADHD symptoms?
There is no single blood test or scan. A screening questionnaire such as our free online ADHD test can indicate whether an assessment is worthwhile, but a diagnosis can only be made by a qualified clinician after a full clinical assessment.
Can ADHD symptoms be treated?
Yes. ADHD is one of the most treatable conditions in mental health. Most people see a significant improvement with medication, and coaching, therapy and practical adjustments help with the areas medication does not cover.
Book an Adult ADHD Assessment
If the symptoms on this page sound like you, an assessment with one of our Consultant Psychiatrists will give you a clear answer. Online assessments are available across the UK for £695, and in-person assessments at our London and Manchester clinics are £1,095. You can book an Adult ADHD Assessment online, or call us on 0203 966 1551 to talk it through first. For children, please see our children’s ADHD clinic.
