Whiplash injury is a term used for neck injury associated with rear-impact collision in motor vehicle accidents. It is thought to be caused by a hyperextension injury to the neck from the initial rear-impact, followed closely by sudden forward neck flexion caused by a secondary front impact, the combination resulting in a whip-like action to the neck. Many of these injuries are however not associated with a secondary front impact. In many instances the severity of the impact bears no relationship to the intensity of symptoms. Severe symptoms may in fact result from a relatively trivial injury.

The condition shares many of the features of fibrositis with chest wall, arm, neck, jaw and head involvement. Neck pain tends to be more severe with greater restriction of neck movements. Symptoms and disability also tend to be more marked. The condition is not unlike fibrositis. It will respond to acupuncture, restriction of pain-inducing activities and encouragement of all other activities, and an active graded exercise program.