An example operation may include one or more of connecting, by a pharmacy node, to a blockchain network configured to store patients' data on a blockchain ledger, receiving, by the pharmacy node, a request from a patient node for a prescription refill, the request contains a secret key of a patient, extracting, by the pharmacy node, the secret key from the request to verify a patient's identity, and executing, by the pharmacy node, a smart contract to: (a) decrypt a prescription data located on the ledger by an application of the secret key, (b) retrieve patient's allergy records from the ledger to check the allergy records against the prescription data, (c) determine a number of remaining refills from the prescription data, (d) check validity of the prescription data based on an expiration date, and commit a prescription refill transaction to the blockchain based on a successful execution of (b)-(d).