Why does toothpaste cause phlemg in throat?

Phlegm in throat: Allergies are the most common cause of the phlemg in throat. The mucus could be coming from your lungs or from your sinus. If you are not coughing much during the day then the source is sinus. Possible allergy to one or more ingredients in toothpaste could be the trigger for your condition. Rec.: try to change your toothpaste brand.

SLS: Most toothpaste has sodium laurel sulfate which is a foaming agent. This is a personal choice but i usually recommend patients use toothpaste that do not have this. It does not do anything to help clean the teeth but cause foam and the feeling of cleaning, so if you want to avoid that just use toothpaste that does not have this.