Background: Bubble hair is an acquired hair shaft deformity characterized by bubble-like areas in the hair shaft seen with light microscopy and corresponding cavitary defects with scanning electron microscopy.
Objective: Our purpose was to report the fourth case of bubble hair, to demonstrate a cause, and to determine whether the cavities contain gas or liquid.
Methods: Light and scanning electron microscopy were performed. The patient's hair dryer was examined. We applied heat to normal hair of the patient and that of 16 human volunteers. Approximate temperatures for bubble formation were measured. The bubble contents were investigated by applying aqueous and nonaqueous liquids to affected hairs.
Results: No person's hair failed to develop bubbles when subjected to sufficient heat. The cause of bubble hair in the patient was an overheating hair dryer. The cavitations contained a gas.
Conclusion: Bubble hair is a reproducible hair shaft defect caused by heat. The use of overheating hair dryers, or any other hair care equipment that overheats, should be avoided.