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 immediately if the person cannot breathe, speak, cry, or cough effectively.
Use age-appropriate choking first aid if you are trained to do so.
If the person becomes unresponsive, begin emergency resuscitation as directed by the emergency dispatcher.
Emergency assessment is also appropriate for blue or grey lips, severe breathing difficulty, collapse, or coughing that began suddenly and does not settle.
And for anyone, someone who:
Seek urgent medical care for:
Contact a healthcare professional or poison information service promptly if a large amount was swallowed, the size is uncertain, the person is a young child, or there is a history of digestive tract narrowing or swallowing problems.
A routine appointment is appropriate for repeated eraser eating without urgent symptoms.
The visit can focus on pica, nutrition, iron levels, development, stress, and ways to reduce future swallowing.
Every sign above is quoted from the sofidex article on Pencil eraser swallowing. If you are not sure, err upward — it is always reasonable to be checked.