The primary cause is food, mucosa lining and bacteria that are stuck in the crypts. Other than that, it is believed that in some cases, it can also indicate a strep throat, in which case one should visit a general physician who will prescribe some antibiotics. Bad oral hygiene is also said to be one of the causes. Some also believe that lack of a proper diet along with lack of exercise and being overweight, could also be a cause but this is unlikely. Among other causes, smoking without a filter has also been linked to tonsil stones.