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 wood stain:
And for anyone, someone who:
Contact a poison centre promptly after any swallowing of wood stain, even if there are no symptoms yet.
In the United States, Poison Help is available at 1-800-222-1222 or through webPOISONCONTROL.
Elsewhere, use your local poison information service.
Have the product label available.
Seek urgent medical assessment for coughing or choking after swallowing, repeated vomiting, unusual drowsiness, wheezing, shortness of breath, persistent eye pain, or blurred vision.
Arrange routine follow-up if a cough, wheeze, rash, headache, concentration problem, or reduced exercise tolerance continues after the initial exposure.
Repeated symptoms linked to work or home projects also need review, even when each episode seems mild.
The article also says
Move away from fumes if this can be done safely.
Do not enter a contaminated enclosed space without proper protection.
Every sign above is quoted from the sofidex article on Wood stain poisoning. If you are not sure, err upward — it is always reasonable to be checked.