The signs of autism can be different depending on the person and how old they are.

Because autism is present from birth, it can usually be diagnosed in childhood. However, it may only be recognised later in life. Understanding of autism has grown over time, so more people are now being diagnosed when they’re older if the signs weren’t recognised when they were children.

These are signs of autism that health professionals look for when making a diagnosis, but an autistic person may not have all of these signs. For example, delayed speech (learning to speak later than most children), or a child not speaking at all, can be a sign of autism. However, many autistic children talk at the same age a child without autism would.

It’s also possible that these signs are there, but they aren’t caused by autism.

If you think you or your child might be autistic, talk to your GP or health visitor.

Signs of autism in children 

The signs of autism can change as children grow – babies and toddlers show different signs of autism than children aged 4 and older. 

Babies and toddlers

Signs of autism in babies and toddlers can include a number of things that affect different parts of their life and behaviour.

Autistic babies and toddlers might:

  • start talking later than most children
  • seem less aware of others around them – for example, they might not respond to their name being called
  • make repetitive movements when excited or upset - for example flapping their hands, rocking back and forth, or making the same noise repeatedly

Autistic babies and toddlers might not:

  • smile back when you smile at them
  • point to show when they want something
  • point to show you something they find interesting
  • share when they’re feeling happy – for example, they might be having fun playing, but they might not turn around and smile at you

Autistic babies and toddlers might:

  • spend a long time setting up toys in a certain way, and set them up the same way every time
  • enjoy lining toys up in order, or watching parts of them move

Autistic babies and toddlers might not:

  • seem interested in playing with other children their age
  • seem to use their toys to make up stories or pretend – they might also start pretend play at a later age than most children

Autistic babies and toddlers might:

  • react strongly to sounds, smells, touch, tastes, or things they can see – for example, if they like the way a stuffed toy feels, they want to spend a lot of time stroking the toy
  • become upset if given something to eat or drink that’s new to them
  • eat a limited range of foods

Children aged 4 and up

As children grow and experience different environments, such as nursery and school, the characteristics of autism can appear differently.

Autistic children might:

  • speak differently to most children – for example, they might use an unusual accent, talk slowly or quickly compared to others, speak in a ‘flat’ tone that doesn’t change, or use a ‘sing-song’ voice
  • use longer or more complicated words than most children, even in relaxed situations
  • struggle to ask other people questions about themselves
  • find it hard to keep a conversation going

Autistic children might:

  • show a great deal of enthusiasm for talking about subjects that interest them, but experience significant difficulty when talking about other people’s interests
  • find it difficult to make and keep friends
  • want to play with other children, but find it hard to ask if they can join in
  • have 1 or 2 good friends that they spend a lot of time with
  • spend free time, such as school break times, by themselves
  • find it hard to tell the difference between someone being friendly or joking and someone trying to bully them or hurt their feelings
  • get on better with adults than other children their age
  • get on better with children who are younger or older than them
  • spend time with a group of children, but find it hard to join in with other children’s play, and so spend a lot of time on the edge of the group
  • have friends at school, but show little to no interest in seeing them outside of school

Autistic children might:

  • accidentally make social mistakes, for example correcting a teacher about classroom rules
  • find some social situations, like parties or busy places, overwhelming and difficult to cope with
  • be passive around other children or adults, agreeing to everything and doing everything people ask
  • often tell others what to do, including while playing
  • struggle with social situations with no timetable or clear ‘rules’, such as free play or school break times
  • find it difficult to cope with changes to their routine, especially if the change is unexpected – for example, having a different teacher for a day or having plans change due to bad weather

Autistic children might:

  • react strongly to sounds, smells, touch, tastes, or things they can see – for example, being unable to cope with seams in their socks or the noises in supermarkets
  • find certain sounds, smells, feelings or tastes particularly calming or enjoyable – for example, coloured lights or being tucked tightly into bed
  • make repetitive movements when excited or upset - for example flapping their hands, rocking back and forth, or making the same noise repeatedly

Signs of autism in teenagers and adults

The characteristics of autism can affect you differently as you get older – you may also recognise some of the signs of autism in children in yourself as an adult. Many people are diagnosed with autism as teenagers or adults based on noticing that they think and behave differently from most other people.

Signs of autism in teenagers

As you age and experience different environments, you might notice different signs of autism.

As an autistic teenager, you might:

  • find it hard to be understood in conversations,
  • find it hard to work out when to talk in conversations – you might never get to say what you want to say, or find yourself talking over other people
  • find it easier to communicate with other autistic people
  • be able to talk for a long time about the subjects that particularly interest you
  • show a great deal of enthusiasm for talking about subjects that interest you, but experience significant difficulty when trying to talk about other people’s interests
  • be able to answer other people’s questions, but struggle to know what questions to ask or how to answer when someone tells you something about themselves
  • find other people say you use a lot of long words, or use longer or more complicated words than most people
  • often use the same phrases when you’re talking
  • struggle with hidden meanings when other people are talking to you – it might be difficult for you to understand a ‘hint’, or notice when someone is flirting with you
  • find people can take the wrong meaning from your words or behaviour – for example, if you make a lot of eye contact, they might think you’re flirting with them

As an autistic teenager, you might:

  • find eye contact uncomfortable, or struggle to know how much eye contact to use
  • do well when you’re in your routine, but find it difficult when routines change – changes might make you feel anxious, make it hard to concentrate, or mean you have to work harder on things it’d normally be easy to do
  • struggle to imagine things that you haven’t experienced before – for example, if you’re going to a party for the first time, it might be hard for you to imagine what will happen and what you’ll be expected to do
  • find yourself making social mistakes without realising why – for example, during conversations you might not realise there are things other people would rather not talk about, or don’t think are important to talk about

As an autistic teenager, you might:

  • have a lot of knowledge on particular topics, and spend a lot of time learning about them and telling others about them
  • have a hobby you feel very passionate about and spend a lot of time on
  • find it hard to start a new activity but get very focused on it once you get started – you might be able to focus on it better than most people
  • find it difficult to stop doing an activity you’re very focused on, even if you need to move on to something else – you might forget to eat or sleep

As an autistic teenager, you might:

  • spend a lot of time being careful to avoid making social mistakes, or trying to make sure you don’t accidentally hurt anyone’s feelings
  • find that other people struggle to understand your feelings from your face or tone of voice
  • find that your friends are often older or younger than you
  • find that your friends tend to be autistic people
  • have to ask people to explain idioms (phrases that say one thing, when they’re actually talking about something else), for example: “we’ll cross that bridge when we come to it”, which means “we’ll talk about that problem later”
  • have a clear idea of right and wrong, and strong views on issues that are important to you – you might struggle to understand exceptions to rules, or ‘grey areas’
  • find a lot of people don’t understand your sense of humour, and you might not understand why their jokes are funny
  • be trusting, and find people can often take advantage of you
  • find it hard to work out when someone is being unkind

As an autistic teenager, you might:

  • have a strong negative reaction to sounds, smells, sights, and things you can touch – for example, being unable to wear certain types of clothing or find it overwhelming being in places with a lot of different noises, like gyms
  • have a strong positive reaction to sounds, smells, sights, and things you can touch – for example, enjoying flashing, multi-coloured lights in nightclubs or how loud the music is at a concert
  • seek out certain sounds, smells, feelings or tastes because you find them particularly calming – for example, coloured lights or soft clothing and blankets
  • find making repetitive movements (often with your hands, fingers or legs) or sounds calming or enjoyable

Signs of autism in adults

As you age and experience different environments, life events, and circumstances, you might notice different signs of autism. You might also have developed coping strategies for environments you find difficult, changing the way you manage them.

As an autistic adult, you might:

  • find it more difficult than most people to communicate in interviews – for example, talking about your skills – which can make it hard to get a job
  • find it more difficult than most people to keep a job – you may be good at your work, but it might be hard to have good relationships with colleagues and managers
  • have a lot of knowledge or feel very passionate about a subject that’s useful for your work or studies
  • find it difficult or frustrating when rules or ways of doing things don’t make sense to you
  • find it more difficult than most people would to work on a project or task that has unclear instructions for how to complete it

As an autistic adult, you might:

  • find socialising hard work – when others seem to have a lot of energy after meeting a group of friends, for example, you might feel exhausted
  • have had relationships with friends or partners end because you couldn’t understand how each other thought, behaved, and communicated
  • find dating challenging
  • prefer to be alone during breaks at work
  • find it difficult to make ‘small talk’ – meaning conversation about day-to-day things such as the weather – or understand the reasons for making small talk
  • enjoy spending time with other people, but find activities that don’t have clear ‘rules’ or a schedule – for example, going to parties or nightclubs – difficult because you aren’t sure what to do
  • prefer meeting up with people to do structured activities, like cooking or taking part in a shared hobby or interest

As an autistic adult, you might:

  • have a lot of detailed knowledge about a particular topic or hobby and feel very passionate about it
  • find that the hobbies or topics you’re particularly passionate about have changed several times in your life

As an autistic adult, you might:

  • find other people often misunderstand you, or seem upset by things you say even if you don’t mean to upset them
  • find it hard to understand why people around you see a situation one way, and not the way you understand it
  • find change more difficult than most people do – things that disrupt your daily routine, like changes to your job or going on holiday, can make you feel stressed and anxious

As an autistic adult, you might:

  • have a strong negative reaction to sounds, smells, sights, and things you can touch – for example, being unable to wear certain types of clothing or find it overwhelming being in places with a lot of different noises, like busy buses or trains
  • have a strong positive reaction to sounds, smells, sights, and things you can touch – for example, enjoying lying under a weighted blanket, or the loudness of the music at a concert
  • seek out certain sounds, smells, feelings or tastes because you find them particularly calming – for example, coloured lights or soft clothing and blankets
  • find making repetitive movements (often with your hands, fingers or legs) or sounds calming or enjoyable

Autistic traits and diagnosis

Autistic traits – meaning things that autistic people often do, think, and feel – are often shared by people who don’t have autism too. This doesn’t mean that everyone is ‘a little bit autistic’, or that autistic people don’t need support.

To be diagnosed with autism, a person has to have a lot of autistic traits from birth, and those traits need to have a big effect on their life. In order to be diagnosed with autism, those traits must cause what a healthcare professional would call ‘clinically significant difficulties’ in their day-to-day life. This means that they have difficulties with day-to-day life due to their autistic traits and need to use their own ways of overcoming those difficulties, or the people in their life need to help them to overcome them, or both.

Being in a supportive environment makes a big difference to an autistic person’s wellbeing and quality of life.

Learn more about how autism is diagnosed

Other health conditions

People who have these conditions can be more likely to also have autism:

  • developmental disorders such as Attention Deficit Hyperactivity Disorder (ADHD) or learning disability
  • muscular dystrophy
  • Down's syndrome
  • cerebral palsy
  • epilepsy
  • neurofibromatosis – a number of genetic conditions that cause tumours to grow along the nerves (the main types are neurofibromatosis type 1 and neurofibromatosis type 2)
  • rare genetic conditions, including fragile X syndrome, tuberous sclerosis and Rett syndrome

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