The Invisalign may turn your teeth yellow especially if you do not brush your teeth often enough when wearing the Invisalign.
When eating food or drinking anything make sure to remove the Invisalign and then brush your teeth after eating before putting the Invisalign back in your mouth.
The Invisalign may also turn yellow as well.
Also wearing Invisalign can give some people a lisp.
However the lisp that you may get from wearing Invisalign is usually only noticeable to you and not anyone else.
When you're wearing Invisalign to straighten your teeth you should not eat with Invisalign on.
Before eating food or drinking anything you should remove the Invisalign before you do eat or drink.
Eating with the Invisalign on could cause damage to the Invisalign or even cause your teeth to get more crooked and also the food could stain the Invisalign as well.
Drinks such as coffee, tea, orange juice etc could also stain the Invisalign so be sure to remove the Invisalign before eating or drinking.
Then put the Invisalign back in your mouth and wear it for 20 to 22 hours per day to help straighten your teeth with it.