Required reporting for serious adverse events and medication errors

The prescribing healthcare provider and/or the provider’s designee is/are responsible for mandatory reporting of all serious adverse events and medication errors potentially related to nirmatrelvir tablets and ritonavir tablets within 7 calendar days from the healthcare provider’s awareness of the event, using FDA Form 3500 (for information on how to access this form, see below).

Serious adverse events are defined as:

  • Death
  • A life-threatening adverse event
  • Inpatient hospitalization or prolongation of existing hospitalization
  • A persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions
  • A congenital anomaly/birth defect
  • Other important medical event, which may require a medical or surgical intervention to prevent death, a life-threatening event, hospitalization, disability, or congenital anomaly

The FDA requires that such reports, using FDA Form 3500, include the following:

  • Patient demographics and baseline characteristics (eg, patient identifier, age or date of birth, gender, weight, ethnicity, and race)
  • A statement “PAXLOVID use for COVID‑19 under Emergency Use Authorization (EUA)” under the “Describe Event, Problem, or Product Use/Medication Error” heading
  • Information about the serious adverse event or medication error (eg, signs and symptoms, test/laboratory data, complications, timing of drug initiation in relation to the occurrence of the event, duration of the event, treatments required to mitigate the event, evidence of event improvement/disappearance after stopping or reducing the dosage, evidence of event reappearance after reintroduction, clinical outcomes)
  • Patient’s preexisting medical conditions and use of concomitant products
  • Information about the product (eg, dosage, route of administration, NDC #)

Required reporting instructions

Submit adverse event and medication error reports, using FDA Form 3500, to FDA MedWatch using one of the following methods:

In addition, please provide a copy of all FDA MedWatch forms to:

Website Fax number Telephone number 1-866-635-8337 1-800-438-1985
Fax number 1-866-635-8337
Telephone number 1-800-438-1985

The prescribing healthcare provider and/or the provider’s designee is/are to provide mandatory responses to requests from the FDA for information about adverse events and medication errors associated with PAXLOVID.

What would you like to learn more about?

Drug Interactions

View boxed warning, contraindicated drugs, and other potentially significant drug interactions.

See Drug Interactions


Learn about the standard and reduced doses of PAXLOVID.

Discover Dosing


See the efficacy data from the phase 2/3 EPIC-HR trial of adult participants with a laboratory-confirmed diagnosis of SARS-CoV-2 infection at high risk for progression to severe disease.

See Efficacy

COVID-19=coronavirus disease 2019; FDA=U.S. Food and Drug Administration; NDC=National Drug Code; SARS-CoV-2=severe acute respiratory syndrome coronavirus 2.


Fact Sheet for Healthcare Providers: Emergency Use Authorization for PAXLOVID™. Pfizer Inc.; 2024.