Originally Posted by LivingNewToday

I do believe it is better to wait awhile and let your saliva and other bodily processes do its thing with the lemon juice before brushing your teeth. The acidity of citrus has an alkaline effect in the body.

I remember hearing somewhere that if you brush right away it is more corrosive, as you're using the fresh acidity of the lemon in abrasing the tooth surfaces. Maybe, just swish and swallow with plain water would be good, if it bothers you.