# CancelRx Message
### Overview
CancelRx is a message type used to discontinue a previously sent prescription electronically through the Surescripts network. It allows prescribers to request cancellation of a [NewRx](newrx-message.md) that was previously sent to a pharmacy.
### How to Send CancelRx Message
To send a CancelRx message, follow these steps:
1. Find the MedicationRequest you want to cancel.
2. Call the CancelRx API endpoint: `POST /e-prescription/rx/cancel`\
Expected payload is a medication request identifier. Unlike [NewRx](newrx-message.md) which accepts a group identifier to send multiple prescriptions at once, CancelRx operates on a single MedicationRequest since cancellations are handled individually per prescription. This allows for more granular control when discontinuing specific medications.
3. Monitor the status of the cancellation using the status fields.
#### Required FHIR Resources
CancelRx requires the same FHIR resources as [NewRx](newrx-message.md) message, with identical validation rules and required fields. The only difference is that for CancelRx the MedicationRequest **must be in either "active" or "completed" status**.
### Status Management
The cancellation status is tracked via two extensions on MedicationRequest:
* `medication-request-cancellation-status`: Tracks the cancellation workflow status
* `medication-request-cancellation-status-reason`: Contains details about the current status
Main MedicationRequest status values remain same as for [NewRx](newrx-message.md). The system will track cancellation workflow via status extensions until we receive a final response from the pharmacy. Only upon receiving a positive cancellation acknowledgment, the MedicationRequest status will be updated to `cancelled`. This helps maintain clear audit trail of prescription state transitions.
It's expected to get a response from pharmacy within 48 hours. If no response is received within this time frame, status will be updated to `unknown` _(since 2.0)_.
#### Status flow
 (1).png)