Final answer:
Monitor the patient closely as anxiety and tachycardia can be side effects of epinephrine. Consult medical control if needed and transport her quickly to a medical facility for further evaluation and care.
Step-by-step explanation:
After administering 0.3 mg of epinephrine via auto-injector to a 22-year-old female with an allergic reaction, you observe improvement in her breathing and resolution of her hives. Noticing that she is still anxious and tachycardic, it's important to recognize that these symptoms can be side effects of epinephrine. Hence, the appropriate action would be to monitor her closely, as anxiety and tachycardia are known potential side effects of the medication. It is not necessarily indicative of a severe reaction to the epinephrine itself. Additional doses of epinephrine or other interventions should only be considered following protocols or after consulting medical control. Rapid transport is also critical to provide her with the necessary care at a medical facility.