Some children show signs of autism spectrum disorder in early infancy, such as less eye contact, not responding to their names or not being interested in caregivers. Other children may not develop as expected for the first few months or years of life. Then they suddenly become withdrawn or aggressive or lose the language skills they had before. Signs usually are seen by ages 2 to 3 years old.

Some people in the mild range on the autism spectrum may have more symptoms that aren't noticed early on. They may not be diagnosed until middle to late childhood, when there is a greater need to communicate and be social. Sometimes a diagnosis is made for the first time in adulthood, though symptoms were likely present during childhood.

Each child with autism spectrum disorder is likely to have a unique pattern of behavior that depends on whether symptoms are mild, moderate or severe.

Some children with autism spectrum disorder have trouble learning, and some have signs of lower than usual intelligence. Other children with the condition have usual to high intelligence. These children learn quickly but have trouble communicating, applying what they know in everyday life and adjusting to social situations.

Because each child can have a unique mix of symptoms, sometimes it can be hard to tell how severe the condition is. It's generally based on how severe the symptoms are and how much those symptoms affect a child being able to function.

Below are some common signs shown by people who have autism spectrum disorder.

Social communication and interaction

People with autism spectrum disorder may have problems getting along with others and communicating. They may have a mix of these and other symptoms:

• Don't respond to their name, or they don't seem to hear at times.
• Don't want to be cuddled or held and prefer to play alone, retreating into their own worlds.
• Have poor eye contact and have no expression on their faces.
• Don't speak or have delayed speech or lose the ability to say words or sentences as they could before.
• Can't start a conversation or keep one going, or only start one to make requests or label items.
• Speak with an unusual tone or rhythm and may use a singsong voice or robotlike speech.
• Repeat words or phrases word for word but don't know how to use them.
• Don't seem to understand simple questions or directions.
• Don't show emotions or feelings and don't seem to be aware of how others feel.
• Don't point at or bring objects to share interest.
• Are passive, aggressive or disruptive when interacting with others.
• Have a hard time figuring out what it means when people have different looks on their faces, position their bodies differently or speak in different tones of voice.

Patterns of behavior

People with autism spectrum disorder may have limited, repetitive patterns of behavior, interests or activities, including a mix of these and other signs:

• Make the same movement over and over again, such as rocking, spinning or hand-flapping.
• Do activities where they could hurt themselves, such as biting or head-banging.
• Create specific routines or rituals and become upset at even small changes.
• Aren't coordinated and may be clumsy, or they move in patterns that aren't usual, such as walking on toes.
• Have unusual, stiff or exaggerated body language.
• Are fascinated by details of an object, such as the spinning wheels of a toy car, but they don't know what the object is for or how it works.
• Are sensitive to light, sound or touch but may not be affected by pain or temperature.
• Don't mimic others or take part in make-believe play.
• Fixate on an object or activity with unusual intensity or focus.
• Prefer specific foods, such as eating only a few foods or not wanting to eat foods with certain textures.

As they get older, some children with autism spectrum disorder interact more with others and show fewer disturbances in behavior. Some, usually those with the least severe problems, eventually may lead typical or nearly typical lives. But others continue to have trouble with language or social skills. And the teenage years can bring more behavioral and emotional challenges.

When to see a doctor

Babies develop at their own pace, and many don't follow exact timelines found in some parenting books. But children with autism spectrum disorder usually show some signs of delayed development before they're 3 years old. Signs of autism spectrum disorder often appear early in development when there are obvious delays in language skills and social interactions.

If you're concerned about your child's development or think that your child may have autism spectrum disorder, talk with a healthcare professional about your concerns. Your healthcare professional may recommend developmental tests to figure out if your child has delays in learning, thinking, language or social skills that point to autism spectrum disorder or another type of developmental condition.

Autism spectrum disorder has no single known cause. Since the condition is complex and symptoms and severity vary, there could be many causes. Both genetics and the environment may play a role.

• Genetics. Several genes seem to be involved in autism spectrum disorder. For some children, autism spectrum disorder can be related to a genetic condition, such as Rett syndrome or fragile X syndrome. For other children, genetic changes, also known as mutations, may raise the risk of autism spectrum disorder. Still other genes may affect the way that the brain develops or brain cells communicate. Or those genes may affect how severe symptoms are. While some genetic changes seem to be inherited, others aren't.
• Environmental factors. Researchers are exploring whether factors such as viral infections, medicines, complications during pregnancy or air pollutants play a role in causing autism spectrum disorder.

No link between vaccines and autism spectrum disorder

One of the greatest controversies in autism spectrum disorder centers on whether there is a link between the condition and childhood vaccines. Many well-done research studies show no link between autism spectrum disorder and any vaccines. In fact, the original study that started the debate years ago was retracted due to poor design and questionable research methods.

When your child doesn't get vaccines, your child and other children could catch and spread viruses that cause serious diseases. These diseases include whooping cough, also known as pertussis, as well as measles, mumps and others.

The number of children diagnosed with autism spectrum disorder is rising. It isn't clear whether this is due to better ways to diagnose and report the condition, a real increase in the number of children with the condition, or both.

Autism spectrum disorder affects children of all races and nationalities. But certain factors raise a child's risk, including:

• Your child's sex. Boys are about four times more likely to be diagnosed with autism spectrum disorder than girls are. While boys may get autism spectrum disorder more often than girls, it's possible that some girls aren't diagnosed.
• Family history. Families who have one child with autism spectrum disorder have a higher risk of having another child with the condition. Sometimes parents or relatives of a child with autism spectrum disorder may have minor problems being social or communicating, or they may show certain behaviors typical of the condition.
• Other conditions. Children with certain medical conditions have a higher risk of autism spectrum disorder or symptoms similar to autism. Examples include fragile X syndrome, an inherited condition that causes intellectual disability; tuberous sclerosis, a condition in which benign tumors develop in the brain; and Rett syndrome, a genetic condition that almost always occurs in girls and causes slowing of head growth, intellectual disability and loss of purposeful hand use.
• Early birth. Babies born before 26 weeks of a parent's pregnancy may have a higher risk of autism spectrum disorder.
• Parents' ages. There may be a connection between children born to older parents and autism spectrum disorder. But more research is needed to show this link.

Because people with autism spectrum disorder often have a hard time interacting socially, communicating or behaving, this can lead to problems with:

• School and learning.
• Getting a job.
• Not being able to live on their own.
• Being isolated socially.
• Stress within the family.
• Being a victim and being bullied.

There's no known way to prevent autism spectrum disorder. But many studies have been done to see if taking folic acid and other vitamins before and during pregnancy can lower the risk of having a baby with autism spectrum disorder. A review of studies on what are known as prenatal vitamins shows no clear answer. This is due to the quality of the research. More high-quality studies are needed.

Getting diagnosed and treated early is most helpful in improving behavior, skills and language development. But getting treatment is helpful at any age. Though children usually don't outgrow autism spectrum disorder symptoms, they may learn to function well.

Your child's healthcare professional looks for signs of developmental delays at regular well-child checkups. If your child shows any symptoms of autism, you'll likely be referred to a specialist who treats children with autism spectrum disorder for an evaluation. This specialist could be a child psychiatrist or psychologist, a pediatric neurologist, or a developmental pediatrician.

Because autism spectrum disorder symptoms and how severe they are can vary widely, it may be hard to make a diagnosis. There is no specific medical test to diagnose autism spectrum disorder. Instead, a specialist may:

• Observe your child and ask how your child has developed or changed over time in terms of interacting socially, communicating and behaving.
• Give your child tests covering hearing, speech, language, level of development, and social and behavioral issues.
• Present structured social and communication interactions to your child and score the performance.
• Include other specialists in coming up with a diagnosis.
• Recommend genetic testing to figure out whether your child has a genetic condition such as Rett syndrome or fragile X syndrome.

There is no cure for autism spectrum disorder, and there is no one-size-fits-all treatment. Treatment seeks to support your child's learning, development and behavior. Getting treated early, during the preschool years, can help your child learn critical social, communication, functional and behavioral skills.

The range of home-based and school-based treatments for autism spectrum disorder can be overwhelming, and your child's needs may change over time. Your healthcare professional can recommend options and help find resources in your area.

If your child is diagnosed with autism spectrum disorder, talk with experts about creating a treatment strategy and build a team of health professionals to meet your child's needs.

Treatment options may include:

• Behavior and communication therapies. Many programs address the range of social, language and behavioral difficulties linked with autism spectrum disorder. Some programs focus on reducing challenging behaviors and teaching new skills. Other programs focus on teaching children how to act in social situations or communicate better with others. Applied behavior analysis can help children learn new skills and adapt these skills to many situations by motivating them with rewards.
• Educational therapies. Children with autism spectrum disorder often respond well to highly structured educational programs. Successful programs usually include a team of specialists and various activities to improve social skills, communication and behavior. Preschool children who get intensive, individualized behavioral treatments often show good progress.
• Family therapies. Parents and other family members can learn how to play and interact with children who have autism in ways that support social interaction skills, manage challenging behaviors, and teach daily living skills and communication.
• Other therapies. Depending on your child's needs, speech therapy to make communication skills better, occupational therapy to teach activities of daily living, and physical therapy to make movement and balance better may help. A psychologist can recommend ways to manage problem behavior.
• Medicines. Medicine can't make the core signs of autism spectrum disorder better, but specific medicines can help control symptoms. For example, certain medicines may be prescribed if your child is hyperactive. Sometimes healthcare professionals prescribe antipsychotic medicines to treat severe behavioral symptoms. Or they may prescribe antidepressants for anxiety. Keep all healthcare professionals updated on any medicines or supplements your child takes. Some medicines and supplements can affect how one medicine acts with another, causing dangerous side effects.

Managing other medical and mental health conditions

In addition to autism spectrum disorder, children, teenagers and adults also can have:

• Medical health issues. Children with autism spectrum disorder also may have medical issues such as epilepsy, sleep disorders, limited food preferences or stomach problems. Ask your child's healthcare professional how to best manage these conditions together.
• Problems with transition to adulthood. Teens and young adults with autism spectrum disorder may have a hard time understanding body changes. Also, social situations become more complex during the teen years, and there may be less tolerance for individual differences. Behavior also may be challenging at this time.
• Other mental health conditions. Teens and adults with autism spectrum disorder often have other mental health conditions, such as anxiety disorders; depression; attention-deficit-hyperactivity disorder, also known as ADHD; and substance misuse. Your healthcare professional, mental health professional, and community advocacy and service organizations can help.
• Behavioral health concerns. In addition to autism spectrum disorder, your child could be irritable or aggressive and may not pay attention. Your child also could be hyperactive, have sudden outbursts or try self-harm. Work with your healthcare professional, mental health professional and other team members to look for a cause, such as pain, distress or frustration, and to manage these challenges if they occur.

Planning for the future

Children with autism spectrum disorder usually continue to learn and come up with ways to handle challenges throughout life. But many continue to need some level of support. Planning for your child's future opportunities can make this process smoother. This includes where to work, go to school and live, and the services required for support, as well as how to be independent and social.

Because autism spectrum disorder can't be cured, many parents seek alternative or complementary therapies. But there's little or no research on these therapies to show whether they're helpful. And some alternative treatments could be dangerous.

Talk with your child's healthcare professional about whether research supports any therapy that you're thinking about for your child.

Examples of complementary and alternative therapies that may offer some benefit when used along with proven treatments include:

• Creative therapies. Some parents choose to include art or music therapy along with educational and medical therapies. Doing so can make a child less sensitive to touch or sound.
• Sensory-based therapies. Therapists may use brushes, squeeze toys, trampolines and other materials to stir the senses, such as touch, balance and hearing. But research has not proved that these therapies work. It's possible that they may help when used with other treatments.
• Melatonin. Research shows that melatonin could help with sleep issues related to autism spectrum disorder when taken as directed. But it's important to work on developing healthy sleep habits first.
• Massage. While massage may be relaxing, there isn't enough evidence to show that it improves symptoms of autism spectrum disorder.
• Pet or horse therapy. Pets can give your child a companion and a fun time. But more research is needed to determine whether being with animals improves symptoms of autism spectrum disorder.

Some complementary and alternative therapies may not be harmful, but there's no evidence that they help. Some also may be costly and hard to carry out. Examples of these therapies include:

• Vitamin supplements and probiotics. Although not harmful when used in the usual amounts, there is no evidence they help autism spectrum disorder symptoms. Also, supplements can be costly. Talk with your healthcare professional about vitamins and other supplements and the right dose for your child.
• Acupuncture. This therapy has been used to improve autism spectrum disorder symptoms, but research doesn't show that it works.

Some complementary and alternative treatments aren't proved to help, and they could be dangerous. Examples of complementary and alternative treatments that aren't recommended for autism spectrum disorder include:

• Special diets that limit nutrients. There's no evidence that special diets effectively treat autism spectrum disorder. And for growing children, restrictive diets can mean that children won't get enough nutrients. If you decide to pursue a restrictive diet, work with a registered dietitian to create a proper meal plan for your child that has all the needed nutrients.
• Chelation therapy. This treatment is said to remove mercury and other heavy metals from the body, but there's no known link between these metals and autism spectrum disorder. Research doesn't support that chelation therapy works, and it can be very dangerous. In some cases, children treated with chelation therapy have died.
• Hyperbaric oxygen treatments. Hyperbaric oxygen involves breathing oxygen inside a pressurized chamber. This treatment has not been shown to be effective in treating autism spectrum disorder symptoms, and the U.S. Food and Drug Administration (FDA) has not approved it for this use.
• Intravenous immunoglobulin (IVIg) infusions. There is no evidence that using IVIg infusions improves autism spectrum disorder symptoms. The FDA has not approved immunoglobulin products for this use.
• Other treatment claims. Treatments that may not be safe or are not proved to help include CBD oil, secretin, antifungal therapy, and clay baths that supposedly remove toxins.

Raising a child with autism spectrum disorder can tire you physically and drain you emotionally. These suggestions may help:

• Find a team of trusted health professionals and others. A team, coordinated by your healthcare professional, may include social workers, teachers, therapists, and a case manager or service coordinator. Team members can help find and assess the resources in your area. They also can explain financial services and state and federal programs for children and adults with disabilities.
• Keep records of visits with healthcare professionals. Your child may have visits, evaluations and meetings with many people on the care team. Keep an organized file of these meetings and reports to help you decide about treatment options and watch progress.
• Learn about the disorder. There are many stories and beliefs that are not true about autism spectrum disorder. Learning the truth can help you better understand your child and attempts to communicate.
• Take time for yourself and other family members. Caring for a child with autism spectrum disorder can put stress on your personal relationships and your family. To avoid burnout, take time out to relax, exercise or enjoy your favorite activities. Try to schedule one-on-one time with your other children and plan date nights with your spouse or partner — even if it's just watching a movie together after the children go to bed.
• Seek out other families of children with autism spectrum disorder. Other families managing the challenges of autism spectrum disorder may have useful advice. Some communities have support groups for parents and siblings of children with the disorder.
• Ask your healthcare professional about new technologies and therapies. Researchers continue to explore new ways to help children with autism spectrum disorder. See the Centers for Disease Control and Prevention website on autism spectrum disorder for helpful materials and links to resources.

Your child's healthcare professional looks for developmental issues at regular checkups. Mention any concerns you have during your appointment. If your child shows any signs of autism spectrum disorder, your child likely will be referred for an evaluation by a specialist who treats children with the condition.

Bring a family member or friend with you to the appointment, if possible, to help you remember information and for emotional support.

Here's some information to help you prepare for your appointment.

What you can do

Before your child's appointment, make a list of:

• Any medicines, including vitamins, herbs, supplements and medicines you buy without a prescription that your child takes. Include the doses.
• Any concerns you have about your child's development and behavior.
• When your child began talking and reaching milestones in development. If your child has siblings, also share information about when they reached their milestones. Milestones are skills that most children can do by a certain age.
• A description of how your child plays and interacts with other children, siblings and parents.
• Any complementary and alternative medicine or therapy your child is getting.
• Questions to ask your child's healthcare professional to make the most of your time.

Also, it may help to bring:

• Notes of any behaviors noticed by other adults and caregivers, such as babysitters, relatives and teachers. If other healthcare professionals or staff members at an early intervention or school program have evaluated your child, bring this assessment.
• A video of your child's unusual behaviors or movements, if you have one.

Questions to ask your child's healthcare professional may include:

• Why do you think my child does or doesn't have autism spectrum disorder?
• Is there a way to confirm the diagnosis?
• If my child has autism spectrum disorder, is there a way to tell how severe it is?
• What changes can I expect to see in my child over time?
• What kind of special therapies or care does my child need?
• How much and what kinds of regular medical care will my child need?
• What kind of support is available to families of children with autism spectrum disorder?
• How can I learn more about autism spectrum disorder?

Don't hesitate to ask other questions during your appointment.

What to expect from your child's doctor

Your child's healthcare professional is likely to ask you several questions. Be ready to answer them to reserve time to go over any points you want to focus on. Your healthcare professional may ask:

• What specific behaviors prompted your visit today?
• When did you first notice these signs in your child? Have others noticed signs?
• Do these behaviors happen all the time or only once in a while?
• Does your child have any other symptoms that don't seem to be related to autism spectrum disorder, such as stomach issues?
• What seems to make your child's symptoms better or worse?
• When did your child first crawl, walk or speak for the first time?
• What are some of your child's favorite activities?
• How does your child get along with you, other siblings and other children? Is your child interested in others? Does your child make eye contact, smile or want to play with others?
• Does your child have a family history of autism spectrum disorder, language delay, Rett syndrome, obsessive-compulsive disorder, or anxiety or other mood disorders?
• What is your child's education plan? What services does your child receive through school?