# Retrieve a patient's allergies

You can use this API action to access a list of patient allergies, as documented by a specific organization. A patient can have an allergy to medication, food, or materials, to name a few. 

> **Prerequisite: Having a patient identifier**
>
> To use this API action, you must know the patient identifier. If you don’t have one, [search for a patient with demographics](/fhir-api-actions/patients/search-for-a-patient-by-demographics) to locate an appropriate identifier first.

## Use cases

This API action may be a good fit for your organization if you perform any of these use cases:

- Decide or know the appropriate medication dosages for a patient’s allergies.
- Understand a patient’s environmental allergies (e.g., latex allergy). 

## Supported systems

You can use this API action with the Redox FHIR API.

> **Talk to a Redoxer**
>
> It’s also possible to use the Redox Data Model API for this API action. [Talk to a Redoxer](https://redoxengine.com/forms/contact-us/) to learn about your options.

Your connection's system can return results with their own FHIR or query-based API. 

## Things you need to know

<details>
<summary>Organization-specific</summary>

You can only search and receive data from one organization for one patient. If you want a comprehensive list for a patient from multiple organizations, you must perform this API action for every organization you’re interested in receiving data from. 

</details>

<details>
<summary>Allergy codes</summary>

Allergies are typically represented in RxNorm codes, but some EHR systems may record allergies as free text. In these cases, Redox sends the values as a normal text string. We recommend that you work with your connection to understand what code sets to expect for allergies.

</details>

<details>
<summary>Allergy status and reaction</summary>

A documented allergy may be active or resolved, and the patient’s reaction may be anywhere from moderate to severe.

The query response contains information to create a holistic view of the documented allergy. Look for:

- whether the allergy is current and needs to be treated; or
- how severe the patient’s reaction may be for a given allergy.

</details>

> **What's next? **
>
> Does this API action seem like a good fit for your unique workflow? Let your Technical Account Manager know! To start development, download the resource schema noted in the related action step. Then decide which data elements you need.
>
> If you’re new to Redox, [use the Quickstart guide](/quickstart-for-redox) to dive in. If you’re not engaged with our sales team yet, [talk to a Redoxer](https://redoxengine.com/forms/contact-us/) to get started.