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Is It Behavior, or Could It Be Pain?

Behavior is communication. Because some autistic individuals may have difficulty recognizing, interpreting, or describing what they feel inside their bodies, pain and illness may show up first as changes in behavior.

Catatonia & Autism

THE MOST IMPORTANT QUESTION

Is this new or significantly
different for this person?

Look for change from the individual’s own baseline, rather than comparing them with someone else.

RECOGNIZING CHANGE

Pain, Illness, and Interoception in Autism

Behavior changes often signal that something important is happening. When an autistic child, teen, or adult suddenly becomes more irritable, withdrawn, anxious, aggressive, or begins engaging in self-injurious behavior, it may be tempting to assume the behavior is related to Autism. However, behavior changes can sometimes be the first sign of pain, illness, or physical discomfort.

Autistic individuals experience the same illnesses and medical conditions as everyone else, including constipation, dental pain, infections, headaches, injuries, and menstrual pain. The challenge is that they may not always recognize, describe, or communicate what they feel in the ways others expect.

UNDERSTANDING

Interoception and Alexithymia

Two concepts can help explain why some autistic individuals may not recognize or communicate pain, illness, or other physical and emotional experiences in expected ways.

Interoception: Understanding What Your Body Is Telling You

Interoception is the ability to notice and understand signals coming from inside your body.

Interoception signals include:

Hunger/Thirst

Feeling full

Needing to use the bathroom

Fatigue

Feel too hot/cold

Nausea

Pain

Stress/Anxiety

Many autistic individuals experience differences in interoception. Some may not notice these signals right away, while others may experience them very intensely. Research suggests interoceptive experiences in Autism can vary considerably from person to person.

For example, a person may:

  • Not realize they are thirsty until they are very dehydrated
  • Not recognize constipation until it becomes severe
  • Struggle to identify that a headache or stomachache is causing distress
  • Have difficulty recognizing when they are becoming anxious or overwhelmed
  • Have trouble localizing pain and discomfort

Alexithymia: Putting Feelings into Words

Alexithymia (pronounced ah-lek-suh-THIGH-mee-uh) means difficulty identifying and describing internal feelings and experiences.

A person with alexithymia may:

  • Know something feels wrong but cannot explain it
  • Have difficulty describing pain
  • Struggle to distinguish between physical discomfort and emotional distress
  • Find it hard to tell others what they are experiencing

Research on pain awareness in autistic individuals has found that difficulties recognizing and communicating pain may be related to alexithymia.

Needing More Prompts

Why These Concepts Matter

An autistic person may experience all three of the following:

  1. Difficulty noticing the body’s signal (interoception)
  2. Difficulty understanding what the signal means
  3. Difficulty finding the words to explain it (alexithymia)
  4. Difficulty localizing pain and discomfort

As a result, pain, illness, discomfort, or anxiety may show up as:

  • Irritability
  • Aggression
  • Withdrawal
  • Self-injurious behavior
  • Changes in sleep
  • Increased repetitive behaviors
  • Refusal to participate in activities

Rather than saying, “My ear hurts,” the individual with ASD may become more distressed, clingy, or aggressive.

LEARN MORE

About Pain

Many people believe that autistic individuals have a “high pain tolerance.” In reality, pain experiences vary widely from person to person. Some autistic individuals may appear less responsive to pain, while others experience pain very intensely.

Differences in sensory processing, interoception, and communication can affect how pain is recognized, experienced, and expressed. As a result, an autistic person may not react to pain in ways others expect, even when they are experiencing significant discomfort.

The absence of a typical pain response does not mean the absence of pain. Families and healthcare providers should avoid assuming that someone is not hurting simply because they are not crying, complaining, grimacing, or pointing to the source of discomfort.

For some autistic individuals, especially those with communication differences, behavior may be the most effective way to communicate pain, discomfort, or illness.

 

Signs that may indicate an underlying medical concern include:

  • Increased irritability
  • Aggression
  • Self-injurious behavior
  • Withdrawal from favorite activities
  • Changes in sleep patterns
  • Increased repetitive behaviors
  • Refusal to participate in daily routines
  • Sudden anxiety or distress
  • Loss of previously developed skills
  • Changes in appetite
  • Changes in toileting habits

A sudden change from a person’s usual behavior should always prompt consideration of a medical cause

Before assuming a behavior is related to Autism, consider whether the person may be experiencing:

  • Constipation
  • Acid reflux, esophagitis or stomach pain
  • Dental problems or tooth pain
  • Ear infections, sinusitis
  • Headaches or migraines
  • Menstrual discomfort
  • Urinary tract infections
  • Injuries, sprains, or fractures
  • Skin irritations, rashes, or allergies
  • Other acute or chronic medical conditions

Many of these conditions can affect mood, attention, participation, and behavior.

Consider:

  • What has changed from the person’s typical behavior
  • When did the change begin
  • Are there changes in eating, drinking, or toileting?
  • Has there been a recent illness, injury, or medication change?
  • Could the person be experiencing pain but having difficulty recognizing or communicating it?
  • Are there signs of constipation, dental pain, headaches, illness, or other physical discomfort?

Families often know their loved one’s baseline behavior better than anyone else. Trust your observations and share them with healthcare providers.

When to Contact a Healthcare Provider

Contact your healthcare provider if:

  • A behavior change is sudden or unexplained
  • Aggression or self-injury has increased
  • Eating, drinking, sleeping, or toileting habits have changed significantly
  • The individual appears uncomfortable but cannot explain why
  • You suspect an illness, injury, or source of pain
  • When consulting with a healthcare provider, it can be helpful to provide a video of the behaviors of concern

Identifying and treating an underlying medical condition can often improve behavior, comfort, participation, and quality of life.

Key Takeaway

Behavior is communication. Because some autistic individuals may have difficulty recognizing, interpreting, or describing what they feel inside their bodies, pain and illness may show up first as changes in behavior.

Before assuming a behavior is “just Autism,” ask: Could this person be trying to tell us that something hurts?

Medical Disclaimer

The information provided is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Contact your healthcare provider if you have concerns about a sudden change in behavior, suspected pain, illness, or other medical symptoms.

Last updated: Oct 2026

References

  • Westby A, Coburn-Pierce M. Autism Spectrum Disorder in Primary Care. American Family Physician. 2025.
  • Hyman SL, Levy SE, Myers SM, Council on Children with Disabilities, Section on Developmental and Behavioral Pediatrics. Identification, Evaluation, and Management of Children With Autism Spectrum Disorder. Pediatrics. 2020.
  • Mahler K. Interoception: The Eighth Sensory System. AOTA Press. 2019.
  • Autism Society. Autism and Health: Understanding Sensory Processing, Communication, and Access to Healthcare.