# MedlinePlus API

> MedlinePlus returns health-topic information and lab test explanations as a workflow and API.

MedlinePlus provides health-topic overviews and related topics; enter a condition or symptom, and optionally choose a language. Explain lab test describes what a test measures, why it may be ordered, preparation, risks, and results; enter a test name.

- Page: https://fous.com/tools/medlineplus
- Handle: `@medlineplus`
- Category: [Health](https://fous.com/tools/category/health)
- Source website: https://medlineplus.gov
- Last verified: Sep 29, 2026

## Methods

### Explain lab test

Operation `explain_lab_test`, version 1. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.

Explain what a MedlinePlus medical test measures, why it may be ordered, how it is done, preparation, risks, and what results mean. Only tests with a matching MedlinePlus Medical Tests page are available.

**Input**

| Field | Type | Required | Example | Description |
|---|---|---|---|---|
| `test` | string | yes | `"A1C"` | Test name on a lab form or report, for example A1C, CBC, or TSH. |

**Input schema**

```json
{
  "type": "object",
  "required": [
    "test"
  ],
  "properties": {
    "test": {
      "type": "string",
      "description": "Test name on a lab form or report, for example A1C, CBC, or TSH.",
      "examples": [
        "A1C",
        "CBC",
        "TSH"
      ]
    }
  },
  "additionalProperties": false,
  "examples": [
    {
      "test": "A1C"
    },
    {
      "test": "CBC"
    },
    {
      "test": "TSH"
    }
  ]
}
```

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `risks` | string or null | `"There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was` | Risks of the test. |
| `used_for` | string or null | `"A complete blood count is often part of a routine checkup . It is also used to monitor a condition or treatment that ma` | What the test is used for. |
| `page_link` | string | `"https://medlineplus.gov/lab-tests/hemoglobin-a1c-hba1c-test/"` | MedlinePlus test page. |
| `test_name` | string | `"Hemoglobin A1C (HbA1c) Test"` | MedlinePlus name of the test. |
| `what_it_is` | string or null |  | What the test is and measures. |
| `other_names` | array |  | Other names listed on the test page. |
| `what_happens` | string or null | `"A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is ` | What happens during the test. |
| `how_to_prepare` | string or null | `"Certain medicines such as opioids and some HIV medicines may affect your results, so tell your provider about everythin` | How to prepare. |
| `what_results_mean` | string or null |  | Explanation of results. |
| `why_you_might_need_it` | string or null | `"Your health care provider may have ordered a complete blood count as part of your checkup or to monitor your overall he` | Reasons the test may be ordered. |

**Example input**

```json
{
  "test": "A1C"
}
```

**Example output**

```json
{
  "risks": "There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.",
  "used_for": "Your blood glucose level changes all the time. If you're checking it at home, you are measuring what your blood glucose level is at that time. An A1C test gives you an average level of your blood gluc…",
  "page_link": "https://medlineplus.gov/lab-tests/hemoglobin-a1c-hba1c-test/",
  "test_name": "Hemoglobin A1C (HbA1c) Test",
  "what_it_is": "A hemoglobin A1C (HbA1C) test is a blood test that shows your average level of blood glucose , also called blood sugar, over the past two to three months.\nGlucose is a type of sugar in your blood that…",
  "other_names": [
    "HbA1C",
    "A1C",
    "glycohemoglobin"
  ],
  "what_happens": "A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You…",
  "how_to_prepare": "Certain medicines such as opioids and some HIV medicines may affect your results, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to…",
  "what_results_mean": "A1C results tell you what percentage of your hemoglobin is coated with glucose. The ranges are just a guide to what is normal. What's normal for you depends on your health, age, and other factors. Ask…",
  "why_you_might_need_it": "The Centers for Disease Control (CDC) recommends A1C testing for diabetes and prediabetes if:\n• You are over age 45. If your results are normal, your provider will tell you how often you should be tes…"
}
```

### Get health topic

Operation `get_health_topic`, version 1. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.

Get a MedlinePlus health-topic overview and related topics for a condition or symptom. Encyclopedia sections are included only when a matching article is linked from that topic; unavailable sections are null.

**Input**

| Field | Type | Required | Example | Description |
|---|---|---|---|---|
| `topic` | string | yes | `"shingles"` | Condition or symptom to look up, for example shingles or back pain. |
| `language` | string | no | `"spanish"` | Language of the overview, for example spanish. |

**Input schema**

```json
{
  "type": "object",
  "required": [
    "topic"
  ],
  "properties": {
    "topic": {
      "type": "string",
      "minLength": 1,
      "description": "Condition or symptom to look up, for example shingles or back pain.",
      "examples": [
        "shingles",
        "back pain"
      ]
    },
    "language": {
      "enum": [
        "english",
        "spanish"
      ],
      "type": "string",
      "default": "english",
      "description": "Language of the overview, for example spanish.",
      "examples": [
        "spanish"
      ]
    }
  },
  "additionalProperties": false,
  "examples": [
    {
      "topic": "shingles"
    },
    {
      "topic": "shingles",
      "language": "spanish"
    },
    {
      "topic": "back pain"
    }
  ]
}
```

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `title` | string | `"Shingles"` | MedlinePlus topic title. |
| `causes` | string or null |  | Causes from a matching medical encyclopedia article. |
| `summary` | string or null |  | Plain-text health topic overview. |
| `symptoms` | string or null |  | Symptoms from a matching medical encyclopedia article. |
| `page_link` | string | `"https://medlineplus.gov/shingles.html"` | MedlinePlus health topic page. |
| `treatment` | string or null |  | Treatment from a matching medical encyclopedia article. |
| `prevention` | string or null | `"Do not touch the rash and blisters on people with shingles or chickenpox if you have never had chickenpox or the chicke` | Prevention from a matching medical encyclopedia article. |
| `other_names` | array |  | Other names of the health topic. |
| `related_topics` | array |  | Related MedlinePlus health topics. |
| `related_topics[].link` | string | `"https://medlineplus.gov/chickenpox.html"` |  |
| `related_topics[].name` | string | `"Chickenpox"` |  |
| `exams_and_tests` | string or null | `"Your health care provider can make the diagnosis by looking at your skin and asking about your medical history. Tests a` | Exams and tests from a matching medical encyclopedia article. |
| `when_to_contact_a_doctor` | string or null | `"Contact your provider if you have symptoms of shingles, particularly if you have a weakened immune system or if your sy` | When to contact a medical professional from a matching medical encyclopedia article. |

**Example input**

```json
{
  "topic": "shingles"
}
```

**Example output**

```json
{
  "title": "Shingles",
  "causes": "After you get chickenpox, your body does not get rid of the virus. Instead, the virus remains in the body but is inactive (becomes dormant) in certain nerves in the body. Shingles occur after the viru…",
  "summary": "What is shingles? Shingles (herpes zoster) is an infection that causes a painful rash. It is caused by the varicella-zoster virus (VZV). This is the same virus that causes chickenpox. After you have c…",
  "symptoms": "The first symptom is usually pain, tingling, or burning that occurs on one side of the body. The pain and burning may be severe and are usually present before any rash appears. Red patches on the skin…",
  "page_link": "https://medlineplus.gov/shingles.html",
  "treatment": "Your provider may prescribe a medicine that fights the virus, called an antiviral medicine. This medicine helps reduce pain, prevent complications, and shorten the course of the disease. The medicines…",
  "prevention": "Do not touch the rash and blisters on people with shingles or chickenpox if you have never had chickenpox or the chickenpox vaccine. The shingles vaccine is different than the chickenpox vaccine. Olde…",
  "other_names": [
    "Herpes Zoster",
    "Postherpetic Neuralgia"
  ],
  "related_topics": [
    {
      "link": "https://medlineplus.gov/chickenpox.html",
      "name": "Chickenpox"
    }
  ],
  "exams_and_tests": "Your health care provider can make the diagnosis by looking at your skin and asking about your medical history. Tests are rarely needed, but may include taking a skin sample to see if the skin is infe…",
  "when_to_contact_a_doctor": "Contact your provider if you have symptoms of shingles, particularly if you have a weakened immune system or if your symptoms persist or worsen. Shingles that affects the eye may lead to permanent bli…"
}
```

## Quick start

Replace `YOUR_API_KEY` with a Fous API key. To create one, open Developers at the bottom of Fous Studio, turn on Developer mode, then go to API keys (https://app.fous.com/keys). Change the values in `input` to run the same tool on new data.

```bash
curl 'https://api.fous.com/v1/query' \
  --fail-with-body --silent --show-error --max-time 180 \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H 'Content-Type: application/json' \
  --data-raw '{
  "api": "@medlineplus",
  "visibility": "public",
  "operation": "explain_lab_test",
  "version": 1,
  "input": {
    "test": "A1C"
  },
  "response": {
    "format": "json"
  }
}'
```

```python
# Save as fous.py and run with python3 fous.py. No packages needed.
import json
import urllib.error
import urllib.request

api_key = "YOUR_API_KEY"

body = json.loads("{\n  \"api\": \"@medlineplus\",\n  \"visibility\": \"public\",\n  \"operation\": \"explain_lab_test\",\n  \"version\": 1,\n  \"input\": {\n    \"test\": \"A1C\"\n  },\n  \"response\": {\n    \"format\": \"json\"\n  }\n}")
request = urllib.request.Request(
    "https://api.fous.com/v1/query",
    data=json.dumps(body).encode("utf-8"),
    headers={
        "Authorization": f"Bearer {api_key}",
        "Content-Type": "application/json",
    },
    method="POST",
)
try:
    with urllib.request.urlopen(request, timeout=180) as response:
        result = json.load(response)
except urllib.error.HTTPError as error:
    raise RuntimeError(f"HTTP {error.code}: {error.read().decode('utf-8', errors='replace')}") from error
if result.get("success") is False:
    raise RuntimeError(result.get("error", {}).get("message", "Request failed"))
print(json.dumps(result["data"]["output"], indent=2))
```

```typescript
// Save as fous.mts and run with npx tsx fous.mts.
const apiKey = "YOUR_API_KEY";

const response = await fetch("https://api.fous.com/v1/query", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  },
  signal: AbortSignal.timeout(180_000),
  body: JSON.stringify({
  "api": "@medlineplus",
  "visibility": "public",
  "operation": "explain_lab_test",
  "version": 1,
  "input": {
    "test": "A1C"
  },
  "response": {
    "format": "json"
  }
}),
});
type ApiResult = { success: boolean; data?: { output: unknown }; error?: { message: string } };
const result: ApiResult = await response.json();
if (!response.ok || result.success === false) {
  throw new Error(result.error?.message ?? `HTTP ${response.status}`);
}
if (!result.data) throw new Error("Missing API response data");
console.log(result.data.output);
```

## Use from an AI assistant

Connect this tool to Claude Code, Claude Desktop, Cursor, VS Code, Codex and any MCP client as its own MCP server. Each method is a typed tool whose arguments are the method’s input.

- Server URL: `https://api.fous.com/mcp/tools/medlineplus`
- Authorization: `Authorization: Bearer <Fous API key>`

**Tools**

- `explain_lab_test`: Explain lab test. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.
- `get_health_topic`: Get health topic. 1 credit per completed call. Failed calls without a completed billing receipt are free; completed work can remain charged if delivery is interrupted.
- `fous_get_run`: the result of a run that was still going, by its `request_id`. Free.

Claude Code:

```bash
claude mcp add --scope user --transport http fous-medlineplus https://api.fous.com/mcp/tools/medlineplus --header "Authorization: Bearer ${FOUS_API_KEY:?Set FOUS_API_KEY to your Fous API key}"
```

To give the assistant every tool, connect `https://api.fous.com/mcp`: it finds one with `fous_search_tools` and runs it with `fous_run_tool`. Setup for other clients: https://fous.com/llms-full.txt.

## Use cases

- Research condition causes, symptoms, and treatment options
- Find related health topics for a condition
- Explain what a lab test measures
- Help patients prepare for a medical test
- Clarify what test results may mean

## FAQ

### Can I run it with my own inputs?

Yes. Change the inputs in Studio and press Run, or send new inputs from your code, or ask a connected AI assistant.

### Can I call this MedlinePlus tool as an API?

Yes. Send a POST request to /v1/query with your Fous API key and the inputs, and get JSON back.

### How much does it cost?

Each completed run costs 1 credit. Failed runs without a completed receipt are free; completed work can remain charged if delivery is interrupted. With pay as you go, a credit costs 1¢. Monthly plans cost less per credit.

### Do I need a MedlinePlus account?

No. You only need a Fous account.

### How current is the data?

Fous gets the data from medlineplus.gov when you run it. Some results are reused for up to 24 hours, and results that use your account or key are never reused. It was last verified on Sep 29, 2026.

### What are the symptoms and treatments for a condition?

Get health topic returns an overview and, when linked information is available, symptoms, treatment, causes, and other details.

### What does a lab test measure?

Explain lab test describes what the test measures, what it is used for, and why it might be needed.

### How should someone prepare for a test?

Explain lab test returns preparation guidance, risks, and an explanation of what results mean.

## Related

- [WebMD API](https://fous.com/tools/webmd.md): Plain-language health condition and symptom guides from WebMD.
- [Mayo Clinic API](https://fous.com/tools/mayo-clinic.md): Mayo Clinic provides health information from public condition pages, including condition overviews and, where available, diagnosis, treatment, home care, alternative medicine, and appointment preparation.
- [PubMed API](https://fous.com/tools/pubmed.md): PubMed searches medical and life-science articles by topic and retrieves one article’s abstract and publication details; abstracts and free full-text links may be unavailable.
- [NLM Clinical Tables API](https://fous.com/tools/nlm-clinical-tables.md): NLM Clinical Tables provides public clinical terminology tables, with diagnosis searches that may miss relevant codes and code explanations checked against current NLM and official classification sources.
- [NHS API](https://fous.com/tools/nhs.md): NHS provides condition and medicine guidance, with condition dates reflecting the latest pages used, and nearby England service listings ordered by distance; availability details may be missing.
- [World Health Organization API](https://fous.com/tools/world-health-organization.md): The World Health Organization provides public health information, latest outbreak reports, country health statistics with up to 10 years of history when available, and topic fact sheets.
- [ClinicalTrials.gov API](https://fous.com/tools/clinicaltrials-gov.md): ClinicalTrials.gov helps users find studies and view public trial records, including sponsor-run or funded studies; site distances are approximate, and contacts, eligibility, or exact dates may be missing.
- [Drugs.com API](https://fous.com/tools/drugs-com.md): Drugs.com provides public medicine guides, interaction and food or lifestyle warnings for 2–10 medicines, pill matches by imprint, color, or shape, and listed US cash prices by strength, form, and quantity.
- [All Health tools](https://fous.com/tools/category/health)