Overview of Severe Autism

The Symptoms and Challenges

There is no such diagnosis as "severe autism." When the term is used, therefore, it's really just a way of describing a person's level of functioning and need.

Severe autism is sometimes called low-functioning autism, classic autism, Kanner's autism (after the person who first described autism as a unique disorder), or profound autism. Simply put, it describes those autistic people with the most significant symptoms.

level 3 autism
 Verywell / Theresa Chiechi

Severe or Level 3 Autism

Another way to describe severe autism is to talk about the level of support required for a person with the diagnosis to function safely. The current diagnostic manual (DSM-5) provides three levels of autism, with more support required at each level.

People with severe autism would usually be diagnosed as having level 3 autism spectrum disorder, meaning they need a great deal of support.

It is not unusual for a person with severe autism to require 24/7 support and supervision.

Severe autism can be much more debilitating and challenging than other types of autism. That's because people with autism have many of the same issues as anyone else on the spectrum, but to a much greater degree, and often have major symptoms that are relatively rare in higher functioning autism.

These two sets of issues can make it virtually impossible for a person with severe autism (or their family) to function well in typical settings ranging from school to the grocery store to the doctor's office.

Severe Versions of Autism Symptoms

To qualify for an autism spectrum diagnosis, a person must have symptoms significant enough to impair daily life. Every autistic person must have social, communication, and sensory challenges that make life more difficult/

Even so-called "high functioning" autism can be very challenging. But those challenges rise to a very different level for people with "severe" autism.

Speech and Language Challenges

While everyone with an autism spectrum disorder has a difficult time with social skills and communication, people with severe autism are most likely to be entirely unable to use spoken language. They may also appear to take no notice of the people around them.

Sensory Dysfunction

Many people on the autism spectrum have sensory dysfunction (they're too sensitive or not sensitive enough to light, sound, touch, taste, or smell). People with severe autism tend to be extremely sensitive, to the degree that going out into crowds, bright lights, or loud noises can be overwhelming.

Cognitive Challenges

Many people with autism have high IQs. Some have IQs at or near 75, the cutoff for what used to be called mental retardation. Generally speaking, however, 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 have learned to communicate using signs, spelling boards, or other tools. Some of those people are quite articulate, and they make it clear that at least some individuals with severe autism are more capable than they appear to be.

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 (violent rocking, door slamming, moaning, etc.).

Physical Symptoms

People with severe autism may have physical symptoms that sometimes appear with less profound autism. These may include sleeplessness, epilepsy, and, according to some sources, gastrointestinal issues.

Because of their difficulties with communication, such issues can go undetected or undiagnosed. The result of undiagnosed physical illness can be behavioral issues that are actually caused by physical pain.

Challenges in Severe Autism

According to some researchers, the extreme behaviors seen in severe autism are very often the result of either frustration, sensory overload, or physical pain. Because people with severe autism have such a hard time communicating their needs verbally, they may find expression in behaviors that can be frightening to their caregivers and others.

If the behaviors can't be addressed or managed, they can actually be dangerous; in many cases, it becomes impossible for parents or siblings to live safely 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 is certainly not unheard of, particularly among people with more severe autism (or among people with autism and 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., which require a quick and effective response.

Wandering and Eloping

"Eloping" (running away with no obvious cause and no particular destination) is also common among people with severe autism. Unlike higher functioning individuals, people with severe autism don't have the tools to communicate with first responders.

This can, of course, increase the likelihood that the individual will wind up in a dangerous situation. In some cases, special locks, alarms, and identification tools are necessary to ensure the safety of a person with severe autism.


As research has shown, there are no treatments that cure severe autism as a disorder. There are, however, a wide range of medical and non-medical options for addressing individual symptoms of severe autism. Some of these are really nothing more than good common sense.

Check for Physical Issues

Few people with severe autism have the ability to describe physical symptoms or problems. Thus, it's a good idea to start by checking whether a child with severe autism has physical symptoms 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—pain which can be treated through dietary changes. Once the pain is gone, the person finds 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 and may repeat sounds without assigning meaning to them.

On the other hand, many of those same individuals 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

For some people with severe autism, a very regular routine along with low lights, few loud noises, predictable foods, and supports for daily activities can be extremely helpful. 

Non-Medical Therapies

Children with severe autism often respond well to applied behavior analysis (ABA), a form of behavioral therapy that is often provided at no charge by school and early intervention programs.

Sensory integration therapy can be helpful, as severe autism often comes with serious sensory challenges. Other useful therapies include speech, occupational therapyphysical therapy, and, sometimes, play therapy


Treatments for severe autism usually include medications for anxiety and related issues. Anti-psychotic drugs can also be effective, as can anti-depressants. It's important to carefully monitor your child's responses to drugs, as—in some cases—side effects or interactions can cause as many problems as they solve.

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