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MedlinePlus Connect: Web Application
URL of this page: https://medlineplus.gov/medlineplus-connect/web-application/

MedlinePlus Connect: Web Application

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MedlinePlus Connect is available as a Web application or Web service. Below are the technical details for implementing the Web application, which responds to requests based on: diagnosis (problem) code requests, drug code requests, lab test code requests, and medical procedure code requests.

If you decide to use MedlinePlus Connect, sign up for the email list to keep up with developments and exchange ideas with your colleagues. Please tell us if you implement MedlinePlus Connect by contacting us. You are welcome to link to and display the data provided by MedlinePlus Connect. For more information on how to link to MedlinePlus content outside of this service, please see our guidelines and instructions on linking.

Web Application Overview

The API for the Web application conforms to the HL7 Context-Aware Knowledge Retrieval (Infobutton) Knowledge Request URL-Based Implementation specification. The structure of the request indicates what type of code you are sending. In all cases, the base URL for the Web application is: https://connect.medlineplus.gov/application

MedlinePlus Connect uses HTTPS connections. HTTP requests will not be accepted and existing implementations using HTTP should update to HTTPS.

Diagnosis (Problem) Code Requests

MedlinePlus Connect matches ICD-10-CM, ICD-9-CM or SNOMED CT codes to related MedlinePlus health topic pages, genetics pages, or pages from other NIH Institutes. For example, a patient diagnosed with ICD-9-CM code 493.12, Extrinsic asthma with exacerbation, could be presented a link in an electronic health record (EHR) that leads to the MedlinePlus page Asthma.

For requests by problem, the base URL of the application is: https://connect.medlineplus.gov/application

This link displays a page with an empty search box. There are two required parameters for any query to this application:

  1. Identify the problem code system you will be using.
    For ICD-10-CM use:
    mainSearchCriteria.v.cs=2.16.840.1.113883.6.90
    For ICD-9-CM use:
    mainSearchCriteria.v.cs=2.16.840.1.113883.6.103
    For SNOMED CT use:
    mainSearchCriteria.v.cs=2.16.840.1.113883.6.96
  2. Identify the actual code that you are trying to look up:
    mainSearchCriteria.v.c=250.33


Optional Parameters

Identify the name/title of the problem code. mainSearchCriteria.v.dn=Diabetes mellitus with other coma type 1 uncontrolled

Identify if you would like the request to be in English or Spanish. MedlinePlus Connect will assume English is the language if it is not specified.

If you wish the response to the problem code lookup to be in Spanish, use : informationRecipient.languageCode.c=es
(=sp also accepted)

To specify English, use the following: informationRecipient.languageCode.c=en

Examples of Requests for Problem Codes

A complete request for Diabetes Mellitus with other coma type 1 uncontrolled, ICD-9 code 250.33, for a Spanish speaking patient would have the following URL address: https://connect.medlineplus.gov/application?mainSearchCriteria.v.cs=2.16.840.1.113883.6.103&mainSearchCriteria.v.c=250.33&mainSearchCriteria.v.dn=Diabetes%20mellitus%20with%20other%20coma%20type%201%20uncontrolled&informationRecipient.languageCode.c=es

A patient diagnosed with "Pneumonia due to Pseudomonas" using SNOMED CT code 41381004: https://connect.medlineplus.gov/application?mainSearchCriteria.v.cs=2.16.840.1.113883.6.96&mainSearchCriteria.v.c=41381004&mainSearchCriteria.v.dn=Pneumonia%20due%20to%20Pseudomonas%20%28disorder%29&informationRecipient.languageCode.c=en

A freeform query, with no code system or problem code, will use the MedlinePlus search engine.

Identify if you would like the request to be sent to the English language MedlinePlus search engine or the MedlinePlus en español search engine. MedlinePlus Connect will assume English as the language if it is not specified and will send the query to the English language MedlinePlus search engine by default: https://connect.medlineplus.gov/application?mainSearchCriteria.v.dn=Type+2+Diabetes

To specify English, use the following: informationRecipient.languageCode.c=en https://connect.medlineplus.gov/application?mainSearchCriteria.v.dn=Type+2+Diabetes&informationRecipient.languageCode.c=en

If the freeform query is in Spanish, then send it to the MedlinePlus en español search engine by using the following: informationRecipient.languageCode.c=es
(=sp also accepted) https://connect.medlineplus.gov/application?mainSearchCriteria.v.dn=Diabetes+Tipo+2&informationRecipient.languageCode.c=es

Drug Code Requests

MedlinePlus Connect provides the best drug information matches when receiving an RXCUI. It also provides good results when receiving an NDC code. MedlinePlus Connect can provide responses to medication code requests in English or Spanish and will return a link to a results page with the best matches from the MedlinePlus drug information.

For requests for English medication information, if you do not send an NDC or RXCUI code or if we find no match based on the code, we will use the text string that you send to display the best drug information match. For requests for Spanish medication information, MedlinePlus Connect responds only to NDCs or RXCUIs; it does not use text strings. It is possible to have a response in English but no response in Spanish.

There may be multiple responses to one medication request. There may not always be a match for each request. If MedlinePlus Connect finds a null response for a drug request, the program displays a search box for the MedlinePlus site. A user can type in a drug name and may get a good response.

For requests for drug information, the base URL is: https://connect.medlineplus.gov/application

Requests for English and Spanish medication information have different requirements. To send a request, include these pieces of information:

  1. Identify the type of medication code you are sending. (Required for English and Spanish)
    For RXCUI use:
    mainSearchCriteria.v.cs=2.16.840.1.113883.6.88
    For NDC use:
    mainSearchCriteria.v.cs=2.16.840.1.113883.6.69
  2. Identify the actual code you are trying to look up. (Preferred for English, Required for Spanish)
    mainSearchCriteria.v.c=637188
  3. Identify the name of the drug with a text string. (Optional for English, Not used for Spanish)
    mainSearchCriteria.v.dn=Chantix 0.5 MG Oral Tablet


For English requests, you should identify at a minimum the code system and the code, or the code system and the name of the drug. Send all three for best results for English requests. For Spanish requests, you should identity the code system and the code.

Optional Parameters

When sending a request for English information, you may include the optional parameter of the name of the medication. This is detailed in the above section. This parameter is not used for Spanish requests.

Identify if you would like the request to be in English or Spanish. MedlinePlus Connect will assume English is the language if it is not specified.

If you wish the response to the medication code lookup to be in Spanish, use: informationRecipient.languageCode.c=es
(=sp also accepted)

To specify English, use the following: informationRecipient.languageCode.c=en

Examples of Requests for Drug Codes

Your drug information request should look like one of the following.

To request information by an RXCUI, your request should look like this: https://connect.medlineplus.gov/application?mainSearchCriteria.v.cs=2.16.840.1.113883.6.88&mainSearchCriteria.v.c=%20637188%20&mainSearchCriteria.v.dn=Chantix%200.5%20MG%20Oral%20Tablet&informationRecipient.languageCode.c=en

To request information by an NDC for a Spanish speaker, your request should look like this: https://connect.medlineplus.gov/application?mainSearchCriteria.v.cs=2.16.840.1.113883.6.69&mainSearchCriteria.v.c=%2000310-0751-39&informationRecipient.languageCode.c=es

To send a text string without a medication code, you must identify your query as an NDC-type request so MedlinePlus Connect knows you are looking for medication information. This will work for English only. Your request could look like this: https://connect.medlineplus.gov/application?mainSearchCriteria.v.cs=2.16.840.1.113883.6.69&mainSearchCriteria.v.dn=Chantix%200.5%20MG%20Oral%20Tablet&informationRecipient.languageCode.c=en

Lab Test Code Requests

MedlinePlus Connect provides matches to laboratory test information when receiving a LOINC request. MedlinePlus Connect can provide responses to lab test requests in English or Spanish and will return a link to a results page with the best matches from the MedlinePlus lab test information.

For requests for lab test information, the base URL is: https://connect.medlineplus.gov/application

These are two required parameters for any lab test query to this application:

  1. Identify that you are using the LOINC code system.
    For LOINC use:
    mainSearchCriteria.v.cs=2.16.840.1.113883.6.1
    MedlinePlus Connect will also accept:
    mainSearchCriteria.v.cs=2.16.840.1.113883.11.79
  2. Identify the actual code you are trying to look up.
    mainSearchCriteria.v.c=3187-2


Optional Parameters

Identify the name/title of the lab test. However, this information does not impact the response. mainSearchCriteria.v.dn=Factor IX assay

Identify if you would like the request to be in English or Spanish. MedlinePlus Connect will assume English is the language if it is not specified.

If you wish the response to the problem code lookup to be in Spanish, use: informationRecipient.languageCode.c=es
(=sp also accepted)

To specify English, use the following: informationRecipient.languageCode.c=en

A freeform query, with no code system or lab code, will use the MedlinePlus search engine. This approach is more effective with diagnoses (see the problem code information above) instead of lab test text strings. Your lab test information request should look like one of the following.

Examples of Requests for Lab Tests

To request information for an English speaker, your request may look like one of the following: https://connect.medlineplus.gov/application?mainSearchCriteria.v.cs=2.16.840.1.113883.6.1&mainSearchCriteria.v.c=3187-2&mainSearchCriteria.v.dn=Factor%20IX%20assay&informationRecipient.languageCode.c=en https://connect.medlineplus.gov/application?mainSearchCriteria.v.cs=2.16.840.1.113883.6.1&mainSearchCriteria.v.c=3187-2&informationRecipient.languageCode.c=en

To request information for a Spanish speaker, your request may look like one of the following: https://connect.medlineplus.gov/application?mainSearchCriteria.v.cs=2.16.840.1.113883.6.1&mainSearchCriteria.v.c=3187-2&mainSearchCriteria.v.dn=Factor%20IX%20assay&informationRecipient.languageCode.c=es https://connect.medlineplus.gov/application?mainSearchCriteria.v.cs=2.16.840.1.113883.6.1&mainSearchCriteria.v.c=3187-2&informationRecipient.languageCode.c=es

Medical Procedure Code Requests

For medical procedure codes, MedlinePlus Connect supports:

MedlinePlus Connect matches CPT® or SNOMED CT procedure codes to related MedlinePlus health topic pages or medical test pages. MedlinePlus Connect can provide responses to procedure requests in English or Spanish and will return a link to a results page with the best matches from MedlinePlus.

For requests for medical procedure information, the base URL is: https://connect.medlineplus.gov/application

These are two required parameters for any procedure query to this application:

  1. Identify the procedure code system you will be using.
    For CPT use:
    mainSearchCriteria.v.cs= 2.16.840.1.113883.6.12
    For SNOMED CT use:
    mainSearchCriteria.v.cs=2.16.840.1.113883.6.96
  2. Identify the actual code you are trying to look up.
    mainSearchCriteria.v.c=59015

Optional Parameters

Identify the name/title of the procedure. However, this information does not impact the response. mainSearchCriteria.v.dn=Chorionic villus sampling

Identify if you would like the request to be in English or Spanish. MedlinePlus Connect will assume English is the language if it is not specified.

If you wish the response to the procedure code lookup to be in Spanish, use: informationRecipient.languageCode.c=es (=sp also accepted)

To specify English, use the following: informationRecipient.languageCode.c=en

Examples of Requests for Medical Procedures

To request information by CPT code for an English speaker, your request may look like one of the following: https://connect.medlineplus.gov/application?mainSearchCriteria.v.c=0001A&mainSearchCriteria.v.cs=2.16.840.1.113883.6.12&mainSearchCriteria.v.dn=&informationRecipient.languageCode.c=en

To request information by SNOMED code for a Spanish speaker, your request may look like this: https://connect.medlineplus.gov/application?mainSearchCriteria.v.c=104107006&mainSearchCriteria.v.cs=2.16.840.1.113883.6.96&mainSearchCriteria.v.dn=&informationRecipient.languageCode.c=es

Acceptable Use Policy

In order to avoid overloading the MedlinePlus servers, NLM requires that users of MedlinePlus Connect send no more than 100 requests per minute per IP address. Requests that exceed this limit will not be serviced, and service will not be restored for 300 seconds or until the request rate falls beneath the limit, whichever comes later. To limit the number of requests that you send to Connect, NLM recommends caching results for a 12-24 hour period.

This policy is in place to ensure that the service remains available and accessible to all users. If you have a specific use case that requires you to send a large number of requests to MedlinePlus Connect, and thus exceed the request rate limit outlined in this policy, please contact us. NLM staff will evaluate your request and determine if an exception may be granted. Please also review the MedlinePlus XML files documentation. These XML files contain complete health topic records and can serve as an alternate method of accessing MedlinePlus data.

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