> ## Documentation Index
> Fetch the complete documentation index at: https://photonhealth.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Screening

> Every prescription is checked against the patient's allergies, medications and diagnoses.

Photon screens a prescription each time its drug resolves or it changes. It checks the drug against the patient's record and returns the result on the prescription:

* **`status`**: `READY`, `WARNING` or `BLOCKED`
* **`screeningAlerts`**: each conflict found

Screening can only check what's on file. [Sync the patient's](/docs/integrations/sync-patients) allergies, medications and diagnoses before drafting. A patient with an empty record gets no alerts, but that doesn't mean the drug is safe.

## Alerts

| Field | Description |
| - | - |
| `type` | What it conflicts with: `DRUG` (another medication), `ALLERGEN` (an allergy) or `CONDITION` (a diagnosis) |
| `severity` | `MINOR` never blocks. `MODERATE` and `MAJOR` block the draft. |
| `description` | A plain-language explanation, ready to show the prescriber |
| `involvedEntities` | The drug and the allergen, medication or condition involved |
| `category` | Usually `SAFETY` |
| `options` | An alternative drug that avoids the conflict, when there is one |

```json theme={"dark"}
{
  "severity": "MODERATE",
  "type": "ALLERGEN",
  "category": "SAFETY",
  "description": "Amoxicillin is a penicillin-class antibiotic. The patient has a recorded allergy to amoxicillin.",
  "involvedEntities": [
    { "id": "med_…", "name": "Amoxicillin 500 MG Oral Capsule" },
    { "id": "alg_…", "name": "Amoxicillin" }
  ]
}
```

## Status

| `status` | Meaning |
| - | - |
| `READY` | No blocking or warning alerts |
| `WARNING` | Alerts to review, none of them blocking |
| `BLOCKED` | At least one `MODERATE` or `MAJOR` alert |

Show every `WARNING` and `BLOCKED` alert to the prescriber before they sign. Prescribe does this for you. Explicit acknowledgement of individual alerts when signing is planned.

<Warning>
  Screening relies on coded entries. An allergy recorded without an RxNorm code, such as a drug-class allergy entered by name, may not be screened. Send allergies by `rxNormId` whenever you can.
</Warning>


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