The limited mobility of the jaw is called trismus. Although initially used to denote tetanus, the term now represents reduced mouth opening due to any cause. It will usually last up to a couple of weeks. On the other hand, long-term trismus might develop, making it more complicated to clean your teeth and gums and even more difficult to get dental treatments done. Several medical issues might cause trismus. Facial, mandibular, or iatrogenic trauma can induce acute trismus. Third molar extraction and intramuscular anesthetic are two instances of iatrogenic injuries. Most cases of acute trismus caused by medication or surgery resolve independently. Chronic trismus is typically caused by severe trauma. Temporomandibular disorders, neoplasia, surgery, radiation therapy for cancer of the head and neck, local infections, and connective tissue disorders such as lupus erythematosus can all lead to chronic trismus.