Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Call emergency services if dry mouth occurs with swelling of your lips, tongue, or throat, trouble breathing, or an inability to swallow.
These symptoms need immediate assessment.
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Seek same-day medical care if you cannot swallow liquids, keep vomiting, pass very little urine, feel faint or confused, or have other signs of severe dehydration.
3
Does any of this apply?
Book an appointment
Book a routine appointment with a doctor or dentist if the dryness:
Lasts for several weeks or keeps returning
Makes it hard to eat, speak, sleep, or wear dentures
Comes with mouth pain, sores, white patches, or tooth problems
Began after starting or changing a medicine
Occurs with very frequent urination, unusual thirst, or persistent dry eyes
The article also says
A dentist can assess the effects on your teeth and gums even if another healthcare professional is investigating the underlying cause.
Every sign above is quoted from the sofidex article on Dry mouth. If you are not sure, err upward — it is always reasonable to be checked.