Overview of Severe Autism

The Symptoms and Challenges

"Severe autism" is a way of describing someone's level of functioning and need. It's not an actual diagnosis.

The official diagnosis is level three autism. The current diagnostic manual (DSM-5) defines autism severity by the amount of support that's needed.

This article will look at what severe autism is, its symptoms and challenges, and how it's managed.

Other Names for Severe Autism

  • Low-functioning autism
  • Classic autism
  • Kanner's autism (after the person who first described it)
  • Profound autism

level 3 autism
 Verywell / Theresa Chiechi

Severe Autism Symptoms

Someone with severe autism often requires 24/7 support and supervision. They face more disability and challenges than those with level one or two symptoms.

Some symptoms are shared by all levels. But others are rare in higher-functioning cases. To be diagnosed with autism, symptoms must impair daily life. Level 3 symptoms have the greatest impact.

Speech and Social Symptoms

Everyone with an autism spectrum disorder (ASD) has a difficult time with social skills and communication.

People with severe autism are most likely to be non-verbal—entirely unable to use spoken language. They may also appear not to notice the people around them.

Sensory Dysfunction

Many people on the autism spectrum have sensory dysfunction. That means they're either too sensitive to or not sensitive enough to:

  • Light
  • Sound
  • Touch
  • Taste
  • Smell

People with severe autism tend to be extremely sensitive, to the degree that crowded, bright, or noisy environments can be overwhelming.

Cognitive Challenges

Many people with autism have high IQs. But some have IQs at or near 75, the cutoff for what used to be called mental retardation.

Generally speaking, people with severe autism have low to very low IQs, even when tested using non-verbal testing tools. It's important to know, however, that appearances can be deceiving.

Some people with severe autism can learn to communicate. They may use sign language, spelling boards, or other tools. Some of them are quite articulate. They prove that at least some people with severe autism are more capable than they may appear.

Repetitive Behaviors

Most people on the autism spectrum have repetitive behaviors and self-stimulatory behaviors.

Higher functioning individuals may flap their hands, rock, or flick their fingers. Often, they can control these behaviors for a period of time when necessary.

People with severe autism are likely to have many such behaviors. And those behaviors can be extreme and uncontrollable. Common ones are violent rocking, door slamming, and moaning.

Physical Symptoms

People with severe autism may have physical symptoms that only sometimes appear with less profound autism. These may include:

  • Sleeplessness
  • Epilepsy
  • Gastrointestinal issues, according to some sources

Because of their communication difficulties, such issues can go undetected or undiagnosed. Undiagnosed physical illness can lead to physical pain, which may cause of worsen behavioral issues.


Severe ASD is called level 3 autism. Level 3 symptoms are the most debilitating. They may include speech and language problems, sensory issues, cognitive deficits, and repetitive behaviors. Physical symptoms (epilepsy, gastrointestinal issues) can worsen behavioral problems.

Challenges in Severe Autism

The extreme behaviors of severe autism may result from frustration, sensory overload, or physical pain.

Some people with severe autism express themselves through frightening behaviors. If the behaviors can't be managed, they can become dangerous.

In many cases, it's not safe for family members to live with a severely autistic teen or adult.


While self-injury can occur among people with milder forms of autism, behaviors such as head-banging and pica (eating non-food items) are far more common among people with severe autism.

Aggressive Behaviors

Aggression is relatively rare in autism. But it's certainly not unheard of, particularly among people with more severe symptoms (or those with other issues, such as severe anxiety).

People with severe autism may act out by hitting, biting, or kicking. They may also have behaviors, such as fecal smearing, door banging, etc., that require a quick and effective response.

Wandering and Eloping

It's common for people with severe autism to wander off. Often there's no obvious cause for running away and no intended destination. This is sometimes called "eloping."

Making the situation worse, people with severe autism generally don't have the tools to communicate with first responders.

This can put the person with ASD in dangerous situations. In some cases, special locks, alarms, and identification tools are necessary to keep them from eloping.


People with severe autism may injure themselves or others through their behaviors (head banging, biting, kicking). They may also put themselves in danger by eloping (wandering away).


Severe autism isn't curable. However, many medical and non-medical treatment options can address symptoms. Some are just common sense.


Treatments for severe autism usually include medications for anxiety and related issues. Anti-psychotic drugs and antidepressants can also be effective.

It's important to carefully monitor the autistic person's responses to drugs. Side effects or negative interactions can cause as many problems as they solve.

Non-Medical Therapies

Children with severe autism often respond well to applied behavior analysis (ABA), a form of behavioral therapy often provided free by schools and early intervention programs.

Sensory integration therapy can be helpful for addressing serious sensory challenges. Other useful therapies include:

Check for Physical Issues

Few people with severe autism are able to describe physical symptoms or problems. So, it's a good idea to regularly check for physical things that may be exacerbating problem behaviors.

It's not uncommon, for example, to discover that a child's apparently aggressive behavior is actually a response to severe gastrointestinal pain. That pain may go away with the right dietary changes.

Once the pain is gone, they usually find it much easier to relax, engage, learn, and behave appropriately.

Teach Communication Skills

Many children with severe autism are non-verbal. Even if they learn to use spoken language, some have a hard time asking or answering questions. They may also repeat sounds without assigning meaning to them.

On the other hand, many of those same people who cannot speak are able to communicate through the use of sign language, picture cards, digital talking boards, and keyboards.

Communication, of course, is the key to any kind of engagement and learning.

Highly Structured, Low-Stress Environment

Sensory issues can be minimized by creating the right environment. Things that may help someone with severe autism include:

  • A very regular routine
  • Low lights
  • Few loud noises
  • Predictable foods


Severe autism, diagnosed as level 3, causes debilitating symptoms. Someone with level 3 autism may be non-verbal and be unable to engage with people. Sensory stimuli may be overwhelming. Cognitive deficits are common. Repetitive behaviors may be extreme and uncontrollable.

These symptoms make for significant challenges such as self-injury, aggressive behaviors, and eloping.

Treatment includes medications and additional therapies (physical therapy, speech therapy). With time and effort, the person with level 3 autism may be able to communicate.

Caregivers need to check for physical problems that may be exacerbating behavioral problems. It's also important to provide an environment with low levels of sensory stimulation.

A Word From Verywell

When someone in your life has severe autism, it presents real challenges. It can help to educate yourself about autism and how it's treated and managed. Work closely with the healthcare team and learn from them, as well.

Remember that you need to take care of yourself, too. Reach out for support when you need it, whether that's to friends and family, social services, a healthcare provider, or a support group.

You may feel alone sometimes, but know other people are out there who understand exactly what you're going through.

Frequently Asked Questions

  • Are there different degrees of autism?

    Yes. Autism spectrum diagnoses can be level 1, level 2, or level 3. Level 1 is considered more high functioning and independent. Level 3 requires significant support and is the most debilitating form of the disorder.

  • Does autism get worse as you get older?

    No, autism doesn't get worse with age. In fact, research shows it may become less. The studies have focused on how symptoms change from early childhood to school age. Girls are more likely to have their autism become less severe as they mature.

  • What does level 3 autism look like?

    People with level 3 autism display many of the typical behaviors of people with level 1 or 2 autism, but to a greater degree. That includes difficulty with social skills, repetitive behaviors, and problems communicating. They often have intellectual disabilities and may require around-the-clock care.

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8 Sources
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