Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
After suspected STEC infection, reduced urination, easy bruising, unusual paleness, or severe tiredness requires prompt assessment.
Routine follow-up may not be necessary when symptoms are mild, hydration is adequate, and the illness steadily improves.
Continue drinking fluids and return to normal food and activity gradually.
Arrange follow-up if diarrhea persists, returns after improving, or is accompanied by weight loss, continuing fever, blood in the stool, or ongoing abdominal pain.
Follow-up is also important if a stool test identifies a bacterium that may require treatment, public health reporting, or confirmation that the infection has cleared.
Some roles and infections require additional precautions or follow-up testing even after symptoms have stopped.
The article also says
Contact a clinician if urination decreases, weakness or dizziness worsens, or vomiting prevents hydration.
A healthcare professional or public health department can advise when it is safe to return to food handling, healthcare, childcare, school, or group living.
Every sign above is quoted from the sofidex article on Bacterial gastroenteritis. If you are not sure, err upward — it is always reasonable to be checked.