The repetitive chewing or consumption of hair, medically termed trichophagia or trichophagy, is a behavior that causes concern for many parents. This action involves placing hair in the mouth, whether for simple chewing or actual ingestion. Hair chewing is a complex behavior that can stem from a variety of sources, ranging from an unconscious habit to a manifestation of deeper neurological or psychological needs. While not a diagnostic criterion for any single condition, it frequently prompts questions regarding developmental differences. Understanding the underlying reasons requires considering sensory, emotional, and behavioral factors. This article explores the contexts in which hair chewing occurs and clarifies its relationship with developmental disorders.
The Specific Relationship Between Chewing and Autism Spectrum Disorder
Chewing on hair is not a standalone symptom for a diagnosis of Autism Spectrum Disorder (ASD). The connection between this behavior and ASD relates to the common presence of repetitive and self-stimulatory behaviors, often called stimming, within the disorder. Stimming serves a function for individuals on the autism spectrum, typically to manage internal states or respond to sensory input.
Oral stimming involves actions of the mouth, such as chewing, sucking, or mouthing objects. For some individuals with ASD, chewing hair provides a specific type of sensory feedback they are seeking. This input is often proprioceptive, referring to the deep pressure and awareness provided by the muscles and joints, particularly in the jaw.
The texture and resistance of hair also offer tactile stimulation, which can be regulating for a nervous system that processes sensory information differently. When a person with ASD experiences sensory overload or emotional distress, engaging in a predictable, repetitive action like hair chewing can be a self-soothing mechanism. It helps to ground the individual and organize overwhelming sensory experiences.
Hair chewing is a non-specific behavior found across many populations, so its presence alone does not indicate an autism diagnosis. A diagnosis of ASD requires a pattern of persistent deficits in social communication and interaction. This must occur alongside restricted, repetitive patterns of behavior, interests, or activities.
Other Reasons for Chewing Hair
When hair chewing occurs outside the context of ASD, it is often categorized as a body-focused repetitive behavior (BFRB). These behaviors are unconscious or semi-conscious actions used to cope with internal states, such as nail-biting or skin-picking. For many, hair chewing is a simple, non-pathological habit that begins during periods of inattention, such as when reading or watching television.
The behavior frequently serves as a mechanism for stress regulation or anxiety management in both children and adults. Chewing provides a physical outlet for nervous energy, momentarily distracting the individual from feelings of tension or boredom. The repetitive motion is a form of self-soothing used to calm the nervous system during emotional distress.
A more concerning cause is Pica, defined as the persistent craving and eating of non-food substances lasting for at least one month. The ingestion of hair (trichophagia) is a specific form of Pica. Pica can sometimes be linked to underlying physiological issues, such as nutritional deficiencies, particularly low levels of iron or zinc.
True trichophagia can co-occur with trichotillomania, which is the compulsive pulling out of one’s own hair. Pica and trichophagia are also associated with other mental health conditions, including anxiety disorders and depression.
When to Consult a Professional
Professional assessment is warranted whenever hair chewing becomes persistent, causes distress, or results in physical harm. A primary care physician or pediatrician is the first point of contact to rule out any immediate medical concerns. They can perform blood tests to check for nutritional deficiencies, such as iron-deficiency anemia, which are sometimes linked to Pica.
One concerning physical risk of hair ingestion is the formation of a hairball, known as a trichobezoar, in the digestive tract. Hair is indigestible, and swallowed hair can accumulate in the stomach, potentially causing a blockage. Signs of a possible trichobezoar include unexplained abdominal pain, nausea, vomiting, or a feeling of fullness after eating a small amount of food.
If the behavior is causing noticeable hair loss or bald patches, or if it is impacting the person’s daily functioning, a referral to a behavioral or mental health specialist is appropriate. These professionals include developmental psychologists or specialized behavioral therapists. They can help determine if the behavior stems from sensory needs, anxiety, or an impulse control disorder.
If the hair chewing has persisted for more than six months or is resistant to simple behavioral intervention, seeking expert guidance is necessary. A professional can conduct a functional analysis to understand the purpose the behavior serves. They can then recommend appropriate strategies, such as providing safe oral sensory alternatives or implementing habit reversal training.