The symptoms of autism spectrum disorders (ASD) can be hard to identify right away. In a 2021 study about delayed diagnosis, more than 75% of participants with ASD didn’t receive their diagnosis for 8 or more years after their first mental health evaluation.
Why is autism undiagnosed or misdiagnosed so often? Part of the complexity comes from the wide variety of ASD symptoms from person to person. No two people experience autism the same way, and subtle symptoms can fly under the radar.
In this guide, Ability Central shares the most common signs of autism, including symptoms in adults and children, to help you understand what ASD looks like and when to seek a diagnosis.
We answer questions like:
How do I know if I have autism?
What are the earliest symptoms of autism?
What are the symptoms of autism in children?
What are the symptoms of autism in adults?
How does autism affect communication?
Why is autism under-diagnosed?
What other conditions can be confused with autism?
If I performed well in school, could I still be autistic?
How do I get tested for autism?
Where can I get more information about autism?
How do I know if I have autism?
Typically, people with autism receive a diagnosis in childhood, sometimes as early as 18 months. Observations from doctors, parents, and teachers can help inform an early diagnosis and develop immediate interventions. But it’s also easy for autism to go unnoticed, undiagnosed, or mistaken for another condition.
Part of the reason may be that many people with ASD mask their symptoms in order to fit in with friends and family. Some aren’t diagnosed with ASD until adulthood because they didn’t miss developmental milestones or had good grades as children. Alternatively, people with mild ASD may not notice their symptoms at all. A doctor might misdiagnose ASD symptoms as a different or co-occurring condition.
If you suspect you or a loved one might have ASD, you’re not alone. Children aren’t the only people diagnosed with ASD. Many adults don’t realize they have autism until they get screened later in life.
To learn more about other conditions associated with or mistaken for autism, see Autism Spectrum Disorders (ASD) Facts: Causes, Diagnosis, and Misconceptions.
What are the most common symptoms of autism?
Autism spectrum disorder (ASD) exists due to structural differences in brain development. ASD affects the way people perceive, think about, and interact with the world and the people around there. Most often, autism is associated with difficulty with social skills, communication, and emotional regulation.
Common symptoms include:
Finding it hard to understand other people's emotions
Anxiety about social situations
Difficulty in making friends
Often being misunderstood and appearing to be blunt or even rude
Taking words and phrases too literally
Having intense anxiety over any changes in the daily routine
Avoiding eye contact
Repetitive tendencies and behavior
Symptoms can be mild or severe. For example, some people with autism carry on conversations quite easily, while others are nonverbal. Someone’s exact symptoms and severity depend on the person, not the diagnosis.
What are the symptoms of autism in children?
Autism symptoms can appear as early as 18 months, but mostly likely by age 2. In toddlers, autism symptoms are often subtle and may be mistaken for a different developmental disability.
The most common autism symptoms in kids include:
Reduced eye contact
Not responding to their name
Not wanting to be held
Preferring time alone
Lack of facial expressions
Delayed speech
Lack of awareness of other people’s feelings
Difficulty recognizing nonverbal cues like facial expressions, body language, or tone of voice
When kids with autism enter school, they may have academic and cognitive challenges. Some symptoms might appear or worsen in response to stress, especially if the child struggles in school. Autism-related behavioral challenges, learning difficulties, and communication problems can be common.
Children with autism may also show symptoms like:
Struggling to make friends (or having no interest in making friends)
Repetitive self-soothing movements like rocking, hand flapping, or spinning in circles
Self-harm (hitting, biting, etc.)
Developing specific rituals and routines, then getting upset at even the smallest changes
Difficulty with coordination or odd mobility
Sensitivities to light, flavors, smells, touch, and other sensory experiences
Being a picky eater
Poor grades, particularly in participation, social activities, or group work
Fixating on activities or objects with unusual focus and intensity (also called “hyperfixation”)
Some kids with autism have fewer, less obvious symptoms as they engage more and more with the outside world. Others struggle with language or social skills that may worsen in their teen and adult years.
What are the symptoms of autism in adults?
As children with autism mature into adults, some symptoms may get better, and others may get worse. The stresses associated with paying bills, starting a family, and holding a job can impact ASD symptoms in adulthood.
Common adult autism symptoms include:
Finding it hard to understand other people's emotions
Anxiety about social situations
Difficulty in making friends
Often being misunderstood and appearing to be blunt or even rude
Taking words and phrases too literally
Having intense anxiety over any changes in the daily routine
Avoiding eye contact
Repetitive tendencies and behavior
On a more personal level, adults with ASD may:
Have always wanted a best friend but never found one.
Invent their own words to describe things.
Repeatedly make involuntary noises, even in quiet places.
Prefer to spend leisure time playing individual games and sports, where everyone works for themselves instead of working toward a common goal on a team.
How does autism affect communication?
Autism spectrum disorders primarily affect social skills, not cognitive or language skills. However, people with autism may have different educational, career, and lifestyle needs.
Because of the social impacts of autism, many people who have autism struggle to make friends and uphold relationships. Poor media portrayal has also contributed to social stigma around ASD.
Because of this, kids—and adults—with autism are often targets for social exclusion or bullying. People with autism may struggle with their emotional regulation. They may also not understand why their view of the world is so different from everyone else’s and assume something is wrong with them, which carries a high risk of mental health issues and low self-esteem.
To learn more about communication with or as a person with autism, see What To Do First After an Autism Diagnosis.
If I performed well in school, could I still be autistic?
Yes. Academic performance is not the only indicator of autism. Interestingly, autism and “giftedness” (exceptionally high intelligence or skill mastery) often go hand-in-hand.
Gifted kids share many symptoms with kids with autism, including getting bored quickly, feeling emotions and sensations more intensely, and focusing closely on things they’re interested in. Many children with a high IQ or ability also face social isolation and communication challenges with their peers.
But you don’t need to be exceptionally intelligent or unintelligent to receive an autism diagnosis. Many people with autism work hard to mask their symptoms, fitting in with others by learning new routines for socializing, schoolwork, and their careers.
How do I get tested for autism?
If you suspect you, your child, or your loved one might have autism, the next step is to schedule an ASD screening. Family doctors, pediatricians, and primary care providers can offer basic autism evaluations. In fact, these are a normal part of developmental check-ins for young children.
There is no blood test or single test for ASD. Instead, doctors use observations from parents, teachers, colleagues, and the patient’s medical and personal history to identify autism symptoms.
From there, your doctor might recommend a specialist for further evaluation, like a speech-language pathologist, child psychologist, neurologist, or occupational therapist.
Testing for autism might include:
Questionnaires filled out by parents and adult patients
Structured tests (like IQ testing, dexterity skills, or tests of imagination)
Examination of life skills (like washing, dressing, and eating)
Self-assessment tests for adults and older teens
Discussion of medical, personal, and family history
To be officially diagnosed with autism spectrum disorders, someone must have symptoms in two categories:
Challenges with social interaction and communication, like making eye contact, holding a conversation, making friends, or reading social cues.
Restricted and repetitive patterns of behavior, like routines, rituals, repetitive movements or speech, or resistance to change.
After a diagnosis, it’s time to explore treatment options like therapy, home- and school-based treatments, or apps that help with task management and life skills. To learn more, see What To Do First After an Autism Diagnosis.
Where can I get more information about autism?
To learn more about autism spectrum disorders (ASD), see:
To learn more about conditions related to or occurring with autism, see:
Muteness (selective mutism)
In addition, Ability Central maintains a searchable database of nonprofits that can help with everything from diagnosis to treatment. Use our Service Locator tool to find an organization near you.
For additional information on autism spectrum disorders, see:
Additional Information
The content provided in this article is for informational purposes only and is not intended as a substitute for legal, medical, or other professional advice. While we strive to provide accurate and up-to-date resources, some information may become outdated or incomplete. Always consult with your provider about personal medical concerns.
