Does the incomplete expectoration of phlegm upon waking affect the fast?

If phlegm does not settle in the mouth and is swallowed directly from the throat, it does not harm the fast. However, if it settles in the mouth and can be expelled, then intentionally swallowing it is a matter of scholarly disagreement. Sheikh Ibn 'Uthaymeen preferred the view that the fast is not invalidated by this, and it is permissible to act upon this opinion for ease, and one should not be overly scrupulous in deliberately trying to expel phlegm from the throat.