Adjuvant pain medications are often prescribed off-label, which means the FDA has not approved its use for treating back or neck pain. (Off-label prescribing is common practice, although some doctors are not comfortable with it.) Skeletal muscle relaxers, tricyclic antidepressants such as amitriptyline, anticonvulsants and corticosteroids are some of the classes of drugs that are considered to be adjuvant.
Generally, adjuvants are used as temporary measures to get you back on your feet again. For example, your doctor may prescribe a muscle relaxer such as cyclobenziprine (aka Flexeril) so that you can participate fully in physical therapy. Because you will likely be given exercises to do, the muscle relaxers can help you do them with less pain, which may help speed your progress.