Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services for a seizure, collapse, severe breathing difficulty, inability to wake the person, or signs of a serious heart-rhythm problem.
And for anyone, someone who:
Seek urgent medical advice for continuing vomiting, increasing weakness, muscle cramps, unusual sleepiness, confusion, reduced urination, or worsening abdominal symptoms.
After a medically significant exposure, follow-up may include repeat electrolyte or kidney-function tests.
This is more likely after severe symptoms, abnormal hospital results, repeated ingestion, or in people with kidney or heart disease.
Arrange routine medical follow-up if the ingestion was related to ongoing indigestion, attempts to change body pH, pica, an eating disorder, confusion, or difficulty using medicines safely.
The goal is to address the reason for the exposure and identify safer treatment or support.
And for anyone, someone who:
The article also says
Follow the instructions from Poison Control or the treating medical team.
A person who remains well after a minor exposure may only need observation for a specified period.
Do not resume intentional use of baking powder as a home remedy.
Every sign above is quoted from the sofidex article on Baking powder overdose. If you are not sure, err upward — it is always reasonable to be checked.