On many occasions, the signs and symptoms of whiplash do not develop immediately following the injury: Frequently, the onset is delayed from two to 48 hours and some individuals do not experience whiplash symptoms for several weeks. Although this scenario is fairly common, the reason is not completely understood, some believe that the delay in muscle soreness is responsible for this circumstance. This is one of the reasons that undergoing an evaluation from an experienced emergency physician following a vehicle accident is essential.