RxNorm API

Free NIH RxNorm API with no key: normalised drug names, ingredients, brand-generic mapping and clinical drug identifiers from the US National Library of Medicine.

No API key requiredCORS enabledHTTPSFree tier

Endpoint tested and returned HTTP 200 on 19 Aug 2026

What is the RxNorm API?

RxNorm is a free, key-free API from the US National Library of Medicine providing normalised drug nomenclature — mapping brand names to generics, resolving ingredients and strengths, and linking to standard clinical drug identifiers.

RxNorm solves the drug naming problem. The same medication appears under dozens of brand names, formulations and spellings across health systems, and RxNorm assigns a normalised concept identifier (RXCUI) that ties them together.

That makes it foundational for any clinical software: given 'Tylenol', 'paracetamol' and 'acetaminophen 500 MG tablet', RxNorm resolves all three to related concepts so you can reason about them as one drug rather than three strings.

Quick facts

Base URL: https://rxnav.nlm.nih.gov/REST
Authentication: No API key required.
Rate limit: 20 requests per second per IP.
Pricing: Free public domain US government data.
CORS: Enabled — callable directly from browser JavaScript
Official docs: Read the docs

How to use the RxNorm API

Every request below was executed against the live API on 19 Aug 2026, and the response shown is the real body it returned — not an illustration.

1. Look up a drug by name

GET https://rxnav.nlm.nih.gov/REST/drugs.json?name=aspirin

curl

curl 'https://rxnav.nlm.nih.gov/REST/drugs.json?name=aspirin'

JavaScript (fetch)

const res = await fetch("https://rxnav.nlm.nih.gov/REST/drugs.json?name=aspirin");
if (!res.ok) throw new Error(`Request failed: ${res.status}`);
const data = await res.json();
console.log(data);

Python (requests)

import requests

res = requests.get("https://rxnav.nlm.nih.gov/REST/drugs.json?name=aspirin", timeout=20)
res.raise_for_status()
print(res.json())

Response — HTTP 200 (truncated)

{
  "drugGroup": {
    "name": null,
    "conceptGroup": [
      {
        "tty": "BPCK",
        "conceptProperties": [
          {
            "rxcui": "2047428",
            "name": "{100 (acetaminophen 250 MG / aspirin 250 MG / caffeine 65 MG Oral Tablet [Excedrin]) / 24 (acetaminophen 250 MG / aspirin 250 MG / diphenhydramine citrate 38 MG Oral Tablet [Excedrin PM Triple Action]) } Pack [Excedrin PM Triple Action Caplets and Excedrin Extra Strength Pain Reliever]",
            "synonym": "Excedrin PM Triple Action Caplets and Excedrin Extra Strength Pain Reliever Kit",
            "tty": "BPCK",
            "language": "ENG",
            "suppress": "N",
            "umlscui": ""
          }
        ]
      },
      {
        "tty": "GPCK",
        "conceptProperties": [
          {
            "rxcui": "1730187",
            "name": "{1 (aspirin 325 MG / dextromethorphan hydrobromide 10 MG / phenylephrine bitartrate 7.8 MG Effervescent Oral Tablet) / 1 (aspirin 500 MG / dextromethorphan hydrobromide 10 MG / doxylamine succinate 6.25 MG / phenylephrine bitartrate 7.8 MG Effervescent Oral Tablet) } Pack",
            "synonym": "1 daytime (aspirin 325 MG / dextromethorphan HBr 10 MG / phenylephrine bitartrate 7.8 MG Effervescent Oral Tablet) / 1 nighttime (aspirin 500 MG / dextromethorphan HBr 10 MG / doxylamine succinate 6.25 MG / phenylephrine bitartrate 7.8 MG Effervescent Oral Tablet) Pack",
            "tty": "GPCK",
            "language": "ENG",
            "suppress": "N",
            "umlscui": ""
          },
          {
            "rxcui": "2047427",

Parameters

Parameter	Type	Required	Description
`drugs.json?name=`	string	Optional	Find all drug concepts matching a name. `aspirin`
`rxcui/<rxcui>/related.json`	path	Optional	Concepts related to a given RXCUI. `1191`
`approximateTerm.json?term=`	string	Optional	Fuzzy match for misspelled drug names. `aspirn`
`tty`	string	Optional	Restrict to term types such as SCD, SBD or IN. `SCD`

Response fields

drugGroup.conceptGrouparray: Groups of concepts by term type (tty).
conceptGroup[].ttystring: Term type: IN ingredient, SCD clinical drug, SBD branded drug, BPCK pack.
conceptProperties[].rxcuistring: The normalised concept identifier — the key output.
conceptProperties[].namestring: Full normalised drug name with strength and form.
conceptProperties[].synonymstring: Alternative name for the same concept.

What you can build with the RxNorm API

Normalise drug names across health record systems
Map brand names to generic equivalents
Build medication search with fuzzy matching for misspellings
Link prescriptions to standard clinical identifiers

Common errors and how to fix them

Empty conceptGroup

The drug name was not recognised.

Fix: Try /approximateTerm.json, which handles misspellings and partial names.

Confusing term types

tty codes are dense clinical terminology.

Fix: IN is the ingredient, SCD a clinical drug with strength and form, SBD the branded equivalent. Pick the level you need.

429

More than 20 requests per second.

Fix: Throttle; RxNorm enforces this per IP.

RxNorm API — frequently asked questions

Is the RxNorm API free?

Yes, completely free with no API key. It is published by the US National Library of Medicine as public domain data.

What is an RXCUI?

The normalised concept identifier RxNorm assigns to a drug concept. It is the key output — it lets you treat different names for the same medication as one entity.

How do I handle misspelled drug names?

Use the /approximateTerm.json endpoint, which does fuzzy matching and is designed for user-entered medication names.

What do the tty codes mean?

Term types. IN is an ingredient, SCD a clinical drug with strength and dose form, SBD the branded equivalent, and BPCK a branded pack. Choose the level of specificity your application needs.

Tools that pair with this API

JSON Formatter

Format, beautify and minify JSON online with 2-space, 4-space or tab indentation. Sort keys alphabetically and catch syntax errors instantly — free and private.

Text Compare

Compare two texts online free and highlight every difference. A private text comparison tool that finds matches and changes right in your browser.

Alternatives to RxNorm API

If RxNorm does not fit, these health & medical apis cover similar ground. Every one was called before publishing, and each links to its own reference page with a working curl command and the response it returned.

API	What it does	Auth	CORS	Last verified
openFDA	Free FDA openFDA API with no key: drug labels, adverse event reports, recalls, device and food safety data from official US regulatory records. Tested example.	No key	Yes	19 Aug 2026
ClinicalTrials.gov	Free ClinicalTrials.gov API with no key: 500,000+ clinical studies worldwide with conditions, interventions, eligibility, locations and results. Tested example.	No key	No	19 Aug 2026
WHO Global Health Observatory	Free World Health Organization API with no key: 2,000+ health indicators by country and year — life expectancy, mortality, immunisation and disease data. Tested.	No key	No	19 Aug 2026
PubChem	Free NIH PubChem API with no key: 100M+ chemical compounds with formulas, molecular weight, structures, synonyms, safety and bioactivity data. Tested.	No key	Yes	20 Aug 2026
CDC Environmental Public Health Tracking	Free CDC Environmental Public Health Tracking API with no key: asthma, air quality, drinking water, heat illness, lead poisoning and climate health measures by state and county.	No key	Yes	21 Aug 2026
CDC Open Data	Free CDC Open Data API with no key: hundreds of public health datasets — mortality, life expectancy, chronic disease, environmental health — queryable with SoQL filters.	No key	Yes	21 Aug 2026

All Health & Medical APIs

RxNorm is an independent third-party service and is not affiliated with ByteTools or ByteVancer. Details on this page were verified on 19 Aug 2026; always check the official documentation before relying on this API in production, as terms and limits can change.