Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Seek emergency care for a seizure, collapse, severe confusion, trouble breathing, inability to awaken, or signs of shock.
And for anyone, someone who:
Contact a clinician or poison center promptly for repeated vomiting, worsening diarrhea, inability to keep fluids down, reduced urination, increasing weakness, or new heart-related symptoms.
Routine follow-up may be appropriate if digestive symptoms persist, hydration remains difficult, or the medical team requested repeat testing.
A clinician may recheck electrolytes, kidney function, or heart rhythm after a more significant exposure.
The article also says
After home observation or discharge from medical care, follow the specific instructions from Poison Control or the treating clinician.
Continue monitoring for new or returning vomiting, diarrhea, weakness, confusion, fainting, breathing difficulty, or abnormal behavior.
To reduce future risk, remove or fence off the plant when this can be done safely.
Wear gloves, keep cuttings and berries away from children and pets, and dispose of them according to local guidance.
Teach children never to eat outdoor berries or leaves without permission from a knowledgeable adult.
Wild plants should not be used as food unless their identity and safety are certain.
Every sign above is quoted from the sofidex article on Blue nightshade poisoning. If you are not sure, err upward — it is always reasonable to be checked.