Some gum users experience soreness in the gums, teeth and jaw. These symptoms usually become more tolerable over time. Do not choose gum if you dislike chewing gum, have dentures, caps, or bridges, or sore jaws. Check with your doctor if you take prescription medicine for depression, asthma, diabetes or other conditions; your medications may need to be adjusted as you quit. Also, consult your doctor if you are pregnant or breastfeeding.
For more information see: http://www.nlm.nih.gov/medlineplus/druginfo/meds/a684056.html