A nurse is preparing to administer vancomycin 1 gram IV over 30 minutes to a 65-year-old patient with MRSA pneumonia. The patient suddenly reports flushing, itching, and facial redness during the infusion. The nurse's priority action is to: I 1. Stop the infusion and notify the provider 2. Slow the rate per protocol and monitor the patient 3. Document the reaction and complete the infusion 4. Administer diphenhydramine and continue the infusion