ADHD Symptoms in Adults: What UK Readers Should Know

Do you ever feel like your mind is constantly racing, or that no matter how hard you try, you just can’t keep up with everyday tasks? You’re not alone. If you’re one of the many UK adults living with undiagnosed ADHD, recognising the signs could be life-changing.

Yet despite how common ADHD is, only 1 in 9 UK adults with the condition actually has a diagnosis.^[1] If you’re among the undiagnosed, you’re missing out on support that could transform your life.

Without an ADHD diagnosis, your everyday life might feel much harder than it needs to be. You might struggle with focus, planning, organisation, or managing emotions. When things go wrong at work or home, you might blame yourself, feel guilty, or be ashamed.

Learning to spot symptoms of adult ADHD can be a powerful turning point. It gives you the clarity to make informed decisions on the best steps to take to address your symptoms.

What Are the Core Symptoms of ADHD?

When it comes to ADHD, it’s important to differentiate between symptoms, the internal experiences you feel, like distractibility or restlessness, and signs, the outward behaviours others might notice.

The core symptoms of ADHD fall into three main categories, which are inattention, hyperactivity, and impulsivity.^[2]

Let’s explore the symptoms in each category.

Inattention

If you have ADHD, you might struggle to stay organised and focused. Common symptoms include:^[3][4]

• Making careless mistakes that affect your work or daily tasks
• Difficulty paying attention to details, even during important activities
• Struggling to maintain focus, often jumping between tasks
• Getting distracted easily, like losing track of conversations or tasks
• Daydreaming or drifting off unexpectedly
• Difficulty organising tasks, schedules, and belongings
• Misplacing important items such as keys or paperwork
• Being forgetful in everyday situations, like missing appointments or deadlines

Symptoms of inattention can make it harder to excel at work or school. But it can also affect life outside of work. For instance, you might struggle to stay organised at home or keep up with chores.

Restlessness or Hyperactivity

Hyperactivity in adults usually doesn’t resemble the high energy seen in children. Instead, symptoms of hyperactivity in adults often show up in the following ways:^[3][4]

• Fidgeting, tapping hands or feet, or squirming in your seat
• Finding it hard to sit still during meetings or quiet activities
• Feeling restless or “on the go” all the time
• Talking excessively or interrupting conversations
• Struggling to engage in activities quietly or calmly

Impulsivity

Impulsivity in ADHD may lead to quick decisions and actions. These are often taken without considering the potential consequences.

Examples of symptoms of impulsivity in ADHD include:^[3][4]

• Interrupting others while they are speaking
• Blurting out answers or finishing other people’s sentences
• Having difficulty waiting your turn in conversations or queues
• Making quick decisions without thinking through consequences
• Intruding on or taking over tasks or activities without permission

Most adults with ADHD experience symptoms across all three categories. However, some may primarily show signs of inattention. Others might struggle with hyperactivity and impulsivity.^[5]

You don’t have to experience every single symptom of ADHD to get a diagnosis. However, the National Institute for Health and Care Excellence (NICE) has specific criteria for a diagnosis. These include the following:^[6]

• Symptoms should have started in childhood. To confirm this, your doctor may ask you or someone who knew you well as a child about your childhood challenges and behaviours.
• Your symptoms are not explained by any other mental health conditions, such as depression, bipolar disorder, or anxiety. However, they may co-exist.
• Symptoms must occur frequently. They should also affect at least two areas of your life, such as your work, academics, family relationships, or social life.

If you’re unsure whether your symptoms meet the criteria for a diagnosis, it’s best to seek a professional assessment. Your mental health professional can evaluate your symptoms and experiences to determine whether they are due to ADHD.

How ADHD Symptoms Show Up in Adults

ADHD often looks different in adults compared to children.

Children tend to show more obvious signs of ADHD. Meanwhile, adults tend to struggle more with subtle symptoms of ADHD, like poor focus or forgetting important details.

While they may be harder to spot, they can still be as disruptive in various areas of life.

At Work or School

In your school or workplace, people might misunderstand your ADHD symptoms as a lack of effort or care. The truth is, they’re simply how your ADHD brain processes tasks and priorities.

Symptoms of ADHD might affect your work or school as follows:

• Being late to meetings, classes, or important events
• Forgetting or missing deadlines
• Having trouble following through on instructions given for tasks or assignments
• Procrastinating or leaving projects and assignments unfinished
• Getting distracted easily and frequently switching between activities
• Having trouble staying focused during meetings or lectures
• Losing important documents or work-related items
• Having a cluttered and disorganised workspace

All of these symptoms can make it harder to perform at your best at work or school. Many adults with ADHD also find it challenging to maintain steady employment.^[7]

In Relationships

Adults with ADHD might run into different relationship roadblocks.

If you have ADHD, you might experience the following in your friendships or relationships:

• Getting distracted easily and finding it hard to listen attentively during conversations
• Interrupting others unintentionally or blurting out hurtful comments without meaning to
• Having emotional outbursts and mood swings, which can cause conflicts
• Forgetting important events and dates, such as anniversaries or birthdays
• Struggling to keep up with household responsibilities, leading to others taking on more of the workload

It’s essential to learn how to manage your emotions and communicate effectively. You can build these skills and strategies with the help of a coach, counsellor, or therapist.

Internal Signs & Emotional Impact

Living with ADHD can take a heavy emotional toll. It is entirely normal to feel overwhelmed, frustrated, or even defeated at times. But it is important to remember these feelings are part of ADHD; they are not a reflection of your worth or effort.

Many adults with ADHD experience emotional dysregulation, which means emotions can feel intense, unpredictable, or challenging to manage. You might find yourself experiencing sudden mood swings, irritability, or low tolerance for stress.^[8] These reactions can sometimes make relationships and daily tasks more challenging.

It is also common for ADHD to co-exist with other conditions like anxiety or depression. These overlapping difficulties can add to feelings of self-doubt, guilt, or shame. But knowing this is not a personal failure, it is a result of how your brain is wired.

Recognising ADHD as a neurodevelopmental condition can be a powerful step toward self-compassion. 

You are not lazy, careless, or “overly dramatic.” You are simply managing a complex condition that requires understanding and support.

Lesser-Known ADHD Traits That Might Be Overlooked

When most people think of ADHD, they picture losing focus, getting restless, or being an impulsive decision-maker.

It’s important to address these common symptoms, but it is just as crucial to acknowledge the hidden, less obvious signs of ADHD in adults.

Some of these traits include:

• Time blindness: Struggling to judge how long tasks will take, underestimating or overestimating time, or losing track of it altogether
• Hyperfocus: Becoming so engrossed in an activity or interest that you lose awareness of everything else around you
• ADHD paralysis: Getting overwhelmed by information or emotions, until you are “frozen” and unable to start your tasks
• Sensitivity to criticism: Feeling disproportionately upset or discouraged by negative feedback or perceived rejection
• Difficulty with routine: Struggling to stick to helpful schedules or finding repetitive tasks boring, tedious, and hard to maintain
• Sleep problems: Having trouble falling asleep, staying asleep, and getting enough high-quality sleep each night^[9]

Recognising that these challenges may be linked to ADHD can be helpful. That way, your healthcare team can develop a more comprehensive management plan that addresses them. 

ADHD vs Everyday Forgetfulness

Everyone forgets things or gets distracted sometimes. However, with ADHD, these challenges are consistent, noticeable, and disruptive.

For example, a person without ADHD might occasionally forget an important appointment. In contrast, someone with ADHD may often miss deadlines, misplace items, or forget instructions they’ve just been given.

Take note that this isn’t about laziness or carelessness. These challenges just stem from how the ADHD brain regulates attention, motivation, and memory.

What to Do If These Symptoms Resonate With You

If many of the above signs and symptoms of ADHD feel familiar to you, it is best to work toward addressing them.

Here are some steps you can take.

• Take an ADHD test. Online ADHD questionnaires ask about your symptoms and experiences to help you gauge whether they’re caused by ADHD. They won’t provide a formal diagnosis, but they can be a helpful first step.
• Speak with your GP. Your GP can help you understand what might be causing your symptoms. They can also discuss next steps and refer you to specialists experienced in assessing adult ADHD.
• Consider a specialist assessment. If your GP agrees your symptoms warrant further investigation, they can refer you for a full evaluation. This can be done under the Right to Choose scheme, which allows you to select a specialist of your choice, potentially reducing your waiting time.

Once you have a formal assessment, you and your healthcare team can decide on the best management plan. This may include medication, therapy, or coaching to make daily life more manageable and fulfilling. 

In the UK, medications and therapies for ADHD are typically prescribed and managed through the NHS. 

If you choose to seek a formal diagnosis through the NHS, be aware that waiting times for adult ADHD assessments can vary widely depending on your local area, sometimes ranging from several months to over a year. Knowing this can help you plan and consider private options if needed.

Why Identifying Symptoms Earlier Makes a Difference

ADHD symptoms can have a significant impact on many areas of your life. Taking the step towards diagnosis might feel overwhelming, but recognising its symptoms early allows you to take proactive steps to improve your life.

There are plenty of management options for adult ADHD. Finding what works best for you might take time. So the sooner your ADHD is diagnosed, the sooner you can work on building an effective personalised plan to address your symptoms. 

If you’d like to learn more about the signs and symptoms of ADHD in adults, check out ADDA+. You’ll find expert-led courses, webinars, resources, and practical tools to help you identify and manage ADHD. You’ll also gain access to support groups to connect with others on the same journey as you.

References

[1] O’Nions, E., El Baou, C., John, A., Lewer, D., Mandy, W., McKechnie, D. G. J., Petersen, I., & Stott, J. (2025). Life expectancy and years of life lost for adults with diagnosed ADHD in the UK: matched cohort study. The British journal of psychiatry: the journal of mental science, 226(5), 1–8. Advance online publication. https://doi.org/10.1192/bjp.2024.199

[2] Williams, O. C., Prasad, S., McCrary, A., Jordan, E., Sachdeva, V., Deva, S., Kumar, H., Mehta, J., Neupane, P., & Gupta, A. (2023). Adult attention deficit hyperactivity disorder: a comprehensive review. Annals of Medicine and Surgery, 85(5), 1802–1810. https://doi.org/10.1097/MS9.0000000000000631

[3] Gomez, R., Chen, W., & Houghton, S. (2023). Differences between DSM-5-TR and ICD-11 revisions of attention deficit/hyperactivity disorder: A commentary on implications and opportunities. World Journal of Psychiatry, 13(5), 138–143. https://doi.org/10.5498/wjp.v13.i5.138

[4] Substance Abuse and Mental Health Services Administration. DSM-5 Changes: Implications for Child Serious Emotional Disturbance [Internet]. Rockville (MD): Substance Abuse and Mental Health Services Administration (US); 2016 Jun. Table 7, DSM-IV to DSM-5 Attention-Deficit/Hyperactivity Disorder Comparison. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519712/table/ch3.t3/

[5] NHS. (2025). ADHD in adults. NHS.UK. https://www.nhs.uk/conditions/adhd-adults/

[6] NICE. (2018). Attention Deficit Hyperactivity Disorder: Diagnosis and Management | Guidance | NICE. Nice.org.uk; NICE. https://www.nice.org.uk/guidance/ng87

[7] Lauder, K., McDowall, A., & Tenenbaum, H. R. (2022). A systematic review of interventions to support adults with ADHD at work-Implications from the paucity of context-specific research for theory and practice. Frontiers in Psychology, 13, 893469. https://doi.org/10.3389/fpsyg.2022.893469

[8] Astenvald, R., Frick, M. A., Neufeld, J., Bölte, S., & Isaksson, J. (2022). Emotion dysregulation in ADHD and other neurodevelopmental conditions: a co-twin control study. Child and adolescent psychiatry and mental health, 16(1), 92. https://doi.org/10.1186/s13034-022-00528-0

[9] Surman, C. B. H., & Walsh, D. M. (2021). Managing Sleep in Adults with ADHD: From Science to Pragmatic Approaches. Brain sciences, 11(10), 1361. https://doi.org/10.3390/brainsci11101361