L
Lemma
API Reference

Reasoning

POST/v1/graph

Ask questions about drugs, side effects, interactions, and contraindications in natural language. Get structured drug-condition relationships with complete FDA evidence.

Overview

The Reasoning API enables natural language queries about drug safety using the Lemma Knowledge Graph. Ask questions and receive structured drug-condition relationships with verified FDA evidence.

Unlike the Search API which returns text segments, the Reasoning API returns structured data with explicit relationships between drugs and conditions, complete with severity levels and supporting evidence.

Request Body

questionstringrequired

Natural language question about drugs or drug safety. The system understands various question formats and can handle complex queries.

Example Questions:

•"Which drugs cause liver damage?"
•"What drugs interact with warfarin?"
•"Show me drugs contraindicated in pregnancy"
•"Does aspirin cause bleeding?"

Response Structure

Success responses follow a standard structure with status: 1, msg, and data containing the actual response payload.

statusinteger

Response status. 1 indicates success.

msgstring

Status message, typically "operation successful".

dataobject

The actual response data containing graph query results.

querystring

Echo of the original question.

resultsarray

Array of drug-condition relationships with FDA evidence.

drugobject

Drug information

namestring

Generic drug name

brand_namesarray

Brand names for the drug

manufacturerstring

Drug manufacturer

ndcarray

National Drug Code identifiers

routearray

Administration routes (e.g., ORAL, TOPICAL)

relationshipobject

Relationship between drug and condition

typestring

Relationship type: "warning", "contraindication", "interaction", "adverse_reaction"

conditionstring

Medical condition or effect

severitystring

Severity level: "life_threatening", "serious", "moderate", "mild", or null if not specified

evidencearray

FDA evidence segments supporting this relationship

textstring

Original FDA label text

fingerprintstring

128-bit binary fingerprint for verification

sectionstring

FDA label section name

sourceobject

Official DailyMed URL

metadataobject

Query metadata including result count and timing information.

countinteger

Total number of results returned

query_time_msfloat

Query execution time in milliseconds

Use Cases

Drug Safety Screening

Check if a drug has specific safety concerns before prescribing. Ask "Does X cause Y?" for binary yes/no with evidence.

Comparative Analysis

Find all drugs with a specific effect or contraindication. Ask "Which drugs cause X?" to get a comprehensive list with severity levels.

Drug Interaction Checks

Identify potential drug-drug interactions. Ask "What drugs interact with X?" to get structured interaction data with FDA evidence.

Error Responses

All error responses follow a standard structure with status: 0, errorCode, and msg fields:

400

Bad Request

Invalid request format or missing required parameters

{ "status": 0, "errorCode": "", "msg": "invalid data" }
500

Internal Server Error

Server error or service temporarily unavailable

{ "status": 0, "errorCode": "", "msg": "internal server error" }
curl
curl -X POST https://api.lemma.la/v1/graph \
  -H "Content-Type: application/json" \
  -H "x-api-key: $LEMMA_API_KEY" \
  -d '{
    "question": "Which drugs cause liver damage?"
  }'

Response

200 OK
{
  "status": 1,
  "msg": "operation successful",
  "data": {
    "query": "Which drugs cause liver damage?",
    "results": [
    {
      "drug": {
        "name": "venlafaxine",
        "brand_names": ["Venlafaxine"],
        "manufacturer": "NuCare Pharmaceuticals,Inc.",
        "ndc": ["68071-3431"],
        "route": ["ORAL"]
      },
      "relationship": {
        "type": "adverse_reaction",
        "condition": "liver damage",
        "severity": null
      },
      "evidence": [
        {
          "text": "Urogenital system— Frequent: metrorrhagia*, prostatic disorder (prostatitis and enlarged prostate)*,...",
          "fingerprint": "10000000111000100001111101011101000100011001111000001100000001001111100100111001101110110000110100011110011011100001011001100110",
          "section": "Adverse Reactions",
          "source": {
            "url": "https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=..."
          }
        }
      ]
    }
    ],
    "metadata": {
      "count": 216,
      "query_time_ms": 64.78
    }
  }
}