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
Get urgent or emergency help for:
Severe confusion, disorientation, hallucinations, or unusual behavior
Fainting, reduced awareness, a seizure, or difficulty waking
Signs of severe dehydration, such as very little urine or marked dizziness
Inability to drink because of vomiting, diarrhea, or reduced alertness
Rapid worsening in someone who is severely malnourished
These symptoms can have several causes.
Emergency assessment is needed to check hydration, blood chemistry, brain function, and other possible conditions.
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 prompt medical advice if symptoms are worsening, you cannot keep food or fluids down, or you develop increasing weakness or confusion.
3
Does any of this apply?
Book an appointment
Arrange a routine medical appointment if you have a persistent sun-sensitive rash together with diarrhea, mouth soreness, poor nutrition, or changes in mood or concentration.
Assessment is also important if you have ongoing diarrhea, major weight loss, a very restricted diet, or a condition that interferes with nutrient absorption.
Every sign above is quoted from the sofidex article on Pellagra. If you are not sure, err upward — it is always reasonable to be checked.