Autism Spectrum Disorder (ASD) Symptoms
By
Brian Mastroianni and Tabitha Britt
Updated on June 5, 2025
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Autism spectrum disorder (ASD) is a developmental condition that affects how people communicate and interact with the world around them.
It can involve symptoms like language and communication problems, issues with social interaction, repetitive behaviors, and difficulty coping with change and altered routines. Symptoms look different for everyone, vary by severity, and often appear in early childhood, though some people aren’t diagnosed until adolescence or adulthood.
Symptoms of Autism Spectrum Disorder
The specific challenges vary depending on the individual and the severity of the condition. Symptoms can appear at different ages for some compared with others, but in most people, symptoms of autism start to show up by age 5.
The signs and symptoms may vary in young children, older children, and adults, but some tend to occur at any age:
- Avoiding eye contact or preferring to be alone
- Struggling to understand others’ feelings or when others are upset
- Not speaking or having trouble developing language skills
- Repeating words or phrases without knowing how to use them
- Getting upset by minor changes in one’s routine or surroundings
- Having intense focus or intensity related to a specific activity or interest
- Having perseverative symptoms (persistent repetition of thoughts, speech patterns, or behaviors beyond what’s considered socially appropriate)
- Making the same movements or gestures over and over again, such as hand flapping or spinning (also known as stimming)
- Having unusual or intense reactions to sounds, smells, tastes, textures, lights, or colors (sensory processing issues)
ASD Symptoms in Babies and Young Children
Symptoms of autism in babies and toddlers often involve differences or delays in learning, language, communication skills, or behavior. Common early signs include a child making little eye contact or not responding to their name.
Children with ASD might display very specific, sometimes intense, interests in subjects that others might not, says Jeremy Veenstra-VanderWeele, MD, director of the division of child and adolescent psychiatry at NewYork-Presbyterian Hospital in New York City. In a conversation, a child with autism might return intently to one topic over and over. That was the case for one child whom Dr. Veenstra-VanderWeele worked with who had a very strong interest in sharks and did not talk about any other topic, for example.
Repetitive behaviors or following the same patterns over and over can also be indicative of ASD when they happen in combination with other symptoms. “A lot of these kids display ritualistic behaviors. Certain things have to happen the same way each time,” Veenstra-VanderWeele says. “They might only feel comfortable in your car going the same way to school every day, for instance.”
Other signs that could indicate a baby or toddler may have autism include the following:
- Delayed skills with language
- Doesn’t make eye contact with others
- Doesn’t respond to their name by 9 months old
- Not showing facial expressions reflecting happiness or sadness by 9 months old
- Doesn’t wave goodbye or make other gestures by age 1
- Doesn’t share interests with others, such as showing you an object they like, by 15 months
- Doesn’t point to things that interest them by 18 months
- Can’t tell when others are upset or hurt by age 2
- Doesn’t notice or join other kids in play by age 3
- Doesn’t play pretend (such as with superheroes) by age 4
- Doesn’t sing, dance, or act by age 5
Not all children with ASD exhibit all of these behaviors, and some signs show up at different ages or in different ways. For instance, a rare pattern of regression called childhood disintegrative disorder (CDD), also known as Heller’s syndrome, is sometimes seen on the autism spectrum. Children with CDD have a period of typical development, usually until age 2 to 4, then experience a significant loss of motor, language, social, and other learned skills. According to the most recent version of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), this specific pattern of regression is considered part of the autism spectrum.
ASD Symptoms in Older Children and Adults
Although ASD is a developmental condition that begins in childhood, it’s sometimes misdiagnosed or not diagnosed until adulthood. Many adults grew up during a time when autism was less understood and studied, meaning early signs might have been overlooked. For these individuals, getting an accurate autism diagnosis as an adult can be helpful for understanding and finding appropriate support.
Diagnosing ASD in previously undiagnosed adults can be challenging because the condition is so variable and can affect people differently over time, especially as people develop ways to manage or mask, or camouflage, their difficulties, says Veenstra-VanderWeele.
While the core diagnostic criteria for adults are the same as for children, a doctor may assess an adult differently than a child. For instance, they may ask about symptoms they have now, what they experienced as a child, and whether they have other health conditions.
Potential symptoms of ASD in older children and adults may include the following:
- Finding it hard to understand what others are thinking or feeling
- Taking things very literally and struggling to understand sarcasm, idioms, or figures of speech
- Difficulty reading nonverbal cues like body language, facial expressions, or tone of voice
- Finding it hard to express their own emotions or understand social rules intuitively
- Avoiding eye contact or finding it uncomfortable
- Having highly focused and intense interests in specific subjects or hobbies
- Repeating certain movements, sounds, or phrases
- Being more or less sensitive to sensory experiences, such as bright lights, loud noises, and certain textures or smells
How Autism Symptoms Can Differ By Sex
Autism symptoms and prevalence may differ between men and boys compared with women and girls. Recent data from the Centers for Disease Control and Prevention showed that ASD was 3.4 times as prevalent among 8-year-old boys than girls in 2022.
Differences in how symptoms appear can contribute to this disparity. For example, research suggests that women and girls with ASD may be more likely to mask their symptoms.
Additionally, some studies suggest that when girls and women with autism experience difficulties, like social challenges or sensory processing issues, they are more likely to turn their distress inward. This might mean they’re more likely to develop anxiety, become depressed, or quietly withdraw. These internalized responses can be harder to spot, since signs of autism are often compared with externalized behaviors, like having a very visible meltdown or becoming disruptive, which can often lead to quicker recognition of autism.
Types and Severity of Autism
Because ASD is a spectrum, symptoms don’t look the same or cause the same degree of challenges for everyone. Doctors describe the severity of a person’s symptoms based on how much support they need. This is broken down into three levels: level 1 (requiring support), level 2 (requiring substantial support), and level 3 (requiring very substantial support).
Level 1 (Requiring Support)
People diagnosed with level 1 ASD require some support in their day-to-day functioning. While noticeable, their challenges with social communication and flexibility might not be immediately obvious to everyone.
Level 1 ASD was previously referred to as high-functioning autism or Asperger’s syndrome; these terms are now part of the singular ASD diagnosis, according to the DSM-5.
People with level 1 ASD often have average or above-average intelligence and don’t have language delays, but they still experience difficulties with social interaction, understanding social cues or expectations, and coping with change. Symptoms of level 1 ASD may include the following:
- Finding it hard to start conversations or make the first move socially
- Responding to others’ attempts to connect in ways that might seem a little unusual or don’t lead to a typical back-and-forth
- Appearing to have less interest in social activities or engaging with others
- Having certain repetitive actions or routines that can sometimes get in the way of daily tasks or make it hard to adapt to new things
- May have some difficulty shifting their attention away from a very strong interest or specific topic they’re focused on
Level 2 (Requiring Substantial Support)
People diagnosed with level 2 ASD require substantial support because they have more significant challenges with social and communication skills and behaviors, and these challenges are apparent even when they have support in place. Symptoms of level 2 ASD can include the following:
- Difficulties with both spoken language and understanding or using nonverbal cues like gestures, facial expressions, or body language
- Showing little interest in starting social interactions or finding it very hard to do so
- Struggling to build friendships or connect with others, even when support is available
- Having very specific, intense interests or engaging in repetitive actions that are obvious to most people and often get in the way of daily activities
- Becoming very upset or frustrated if their strong interests, routines, or repetitive behaviors are disrupted
Level 3 (Requiring Very Substantial Support)
People diagnosed with level 3 ASD require very substantial support due to severe challenges with social, learning, and communication skills and behaviors that significantly interfere with functioning in all areas of life. Both verbal and nonverbal social communication are severely limited. Symptoms of level 3 ASD can include the following:
- Making few, if any, attempts to start social interactions with others
- Showing minimal, if any, reaction when other people try to engage with them socially
- Having extremely limited use of spoken language, perhaps only a few words or no words at all
- Being intensely focused on specific topics or objects, following rigid routines, or engaging in repetitive actions that disrupt most areas of life
- Finding it incredibly difficult to cope with any changes in their routine or surroundings
Potential Complications of Autism Spectrum Disorder
People with ASD often experience other medical and psychiatric conditions. Common conditions and challenges associated with ASD include the following:
- Sleep disorders, epilepsy, migraine, cerebral palsy, and obesity
- Psychiatric and behavioral health conditions or issues, such as anxiety, depression, attention deficit hyperactivity disorder, aggression, self-injury, food refusal, wandering, and tantrums
- Intellectual disabilities and differences in language development
- Problems in school, including difficulties with learning and academic achievement
- Challenges with employment and maintaining a job
- Social isolation and challenges in forming and maintaining relationships with peers
- Experience of victimization or being bullied in school or elsewhere
When to See a Doctor
If you notice certain signs or have concerns about yourself or your child, it’s important to talk to a doctor for a potential diagnosis. Let your or your child’s doctor know if you or your child has any of the symptoms described here.
The Takeaway
- Autism spectrum disorder is a complex developmental condition with a wide range of symptoms that vary from person to person and can change over time.
- Symptoms can show up differently depending on a person’s age and required level of support, and may sometimes present differently in men and boys than women and girls
- ASD is often associated with other medical, psychiatric, or behavioral health conditions and can lead to challenges in areas like learning, social interaction, and daily living.
- If you have concerns about developmental differences or potential signs of ASD, talking to a healthcare professional is the best way to get an accurate evaluation and find appropriate support.
Resources We Trust
- Mayo Clinic Health System: Understanding Autism: The Path to Diagnosis, Awareness, and Support
- Cleveland Clinic: Autism Therapies
- Centers for Disease Control and Prevention: Clinical Testing and Diagnosis for Autism Spectrum Disorder
- Autistic Self Advocacy Network: Beyond Coercion and Institutionalization: People With Intellectual and Developmental Disabilities and the Need for Improved Behavior Support Services
- Autism Society: New Autism Diagnosis
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
- Signs and Symptoms of Autism Spectrum Disorder. Centers for Disease Control and Prevention. May 16, 2024.
- Autism spectrum disorder. Mayo Clinic. May 22, 2025.
- ICD-10, International Statistical Classification of Diseases and Related Health Statistical Classification of Diseases and Related Health Problems. Tabular List, 2022. National Center for Health Statistics. March 17, 2022.
- Ellis M et al. Childhood Disintegrative Disorder (CDD): Symptomatology of the Norwegian Patient Population and Parents’ Experiences of Patient Regression. Journal of Autism and Developmental Disorders. May 2, 2021.
- Signs that a child or adult may be autistic. National Autistic Society.
- How To Pursue an Autism Diagnosis as an Adult. Cleveland Clinic. November 20, 2024.
- Prevalence and Early Identification of Autism Spectrum Disorder Among Children Aged 4 and 8 Years — Autism and Developmental Disabilities Monitoring Network, 16 Sites, United States, 2022. Centers for Disease Control and Prevention. April 17, 2025.
- Horwitz E et al. Sex differences in the course of autistic and co-occurring psychopathological symptoms in adolescents with and without autism spectrum disorder. Autism. January 21, 2023.
- Napolitano A et al. Sex Differences in Autism Spectrum Disorder: Diagnostic, Neurobiological, and Behavioral Features. Frontiers in Psychiatry. May 13, 2022.
- Waizbard-Bartov E et al. Autism severity and its relationship to disability. Autism Research. September 14, 2023.
- Diagnostic Criteria for Autism Spectrum Disorder in the DSM-5. Children’s Hospital of Philadelphia. June 9, 2020.
- High-functioning autism (HFA). American Psychological Association. November 15, 2023.
- Hosseini S et al. Asperger Syndrome. StatPearls. February 12, 2024.
- Hodis B et al. Autism Spectrum Disorder. StatPearls. January 17, 2025.
Meet Our Experts
Lee S. Cohen, MD
Medical Reviewer
Lee S. Cohen, MD, is an associate professor of clinical psychiatry at Columbia University Irving Medical Center, maintains a clinical practice focused on expert and complex diagnostics, and is considered an international expert in clinical psychopharmacology. He is also the director of the Clinical Neuroscience Center, involved in innovative development and discovery of new compounds for neuropsychiatric conditions and directly consults with multiple pharmaceutical companies worldwide.
Dr. Cohen graduated from the Sophie Davis Biomedical Education Program at the CUNY School of Medicine at The City College of New York, an accelerated six-year BS/MD program. He then completed his MD at SUNY Stony Brook School of Medicine.
He trained in pediatrics and adult psychiatry at Mount Sinai Hospital in New York City, followed by a fellowship in child and adolescent psychiatry at New York Presbyterian Columbia University Irving Medical Center. He served for 20 years as the director of psychiatry at the Clinical Neuroscience Center at Mount Sinai West Hospital.
He is a senior reviewer for multiple journals, including the Journal of Child and Adolescent Psychopharmacology, the Journal of Developmental and Physical Disabilities, and the International Journal of Autism and Related Disabilities.
Cohen teaches and presents research domestically and internationally at meetings such as those of the American Psychiatric Association and at major universities around the country.
Brian Mastroianni
Author
Brian is a New York City–based science and health journalist. Whether interviewing newsmakers — from Buzz Aldrin, Katie Couric, and Dr. Anthony Fauci to Wendy Williams and the cast of Queer Eye — and tech experts about the latest innovations, or leading medical researchers, he's comfortable chatting with just about anyone.
Brian’s work has been published by The Atlantic, The Paris Review, The New York Times For Kids, CBS News, The Today Show, Barron's PENTA, Engadget, Healthline, and more. He's also hosted podcasts: On Topic, Off Script with Brian Mastroianni as well as Re:solve Talks, from Re:solve Global Health.