Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Schools, workplaces, and caregivers may also need a written emergency plan.
Use epinephrine and call emergency services for trouble breathing, throat or tongue swelling, faintness, collapse, or rapidly developing symptoms in more than one body system.
Emergency care should not be replaced by a routine clinic appointment.
And for anyone, someone who:
Seek prompt medical care for swelling that is severe, continues to worsen, affects function, or may be infected.
Arrange routine follow-up with a healthcare professional after any reaction that caused widespread hives, swelling away from the sting, breathing symptoms, vomiting, dizziness, or fainting.
Ask whether referral to an allergist is appropriate.
The article also says
People prescribed epinephrine should review their technique regularly and replace devices before they expire.
Bring auto-injectors to appointments so a clinician or pharmacist can check the device and demonstrate its use.
People receiving venom immunotherapy need scheduled injections and monitoring in a medical setting.
Tell the allergy team about reactions after injections, new medical conditions, pregnancy, or changes in heart and blood pressure medicines.
Every sign above is quoted from the sofidex article on Allergies to insect stings. If you are not sure, err upward — it is always reasonable to be checked.