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 now if someone exposed to talcum powder:
And for anyone, someone who:
Contact a poison information service promptly after a substantial exposure, after any exposure involving breathing symptoms, or if a baby or young child inhaled powder.
In the United States, Poison Control is available at 1-800-222-1222 .
Elsewhere, use your local poison centre or urgent medical service.
Seek urgent medical assessment for persistent coughing, wheezing, chest pain, repeated vomiting, or shortness of breath.
Symptoms that worsen over the hours after exposure should not wait for a routine appointment.
Routine follow-up is appropriate for a cough or reduced exercise tolerance that continues after the immediate illness, or for symptoms linked to repeated workplace exposure.
The article also says
Move the person away from airborne powder if this can be done safely.
Do not give food or drink to someone who is unconscious or struggling to breathe.
Every sign above is quoted from the sofidex article on Talcum powder poisoning. If you are not sure, err upward — it is always reasonable to be checked.