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NLM Privacy Policy

The National Library of Medicine (NLM) provides this Web site as a public service. We do not collect any personally identifiable information (PII) about you when you visit our Web sites unless you choose to provide that information to us. We do collect some data about your visit to our Web site to help us better understand how the public uses the site and how to make it more helpful. NLM never collects information for commercial marketing or any purpose unrelated to NLM's functions.

Type of Information Collected

When you visit any Web site, certain information about your visit can be collected. NLM automatically collects and temporarily stores the following type of information about your visit:

  • Internet address and domain from which you visited the NLM Web site
  • Information about the operating system and browser used
  • Date and time of the visit
  • Pages visited
  • Internet address of the Web site that connected you to the NLM Web site
  • Words searched

This information is used to measure the number of visitors to the various sections of our site and improve organization, coverage, system performance or problem areas. This information is not used for associating search terms or patterns of site navigation with individual users. When search features offer suggested terms, these suggestions are based on aggregated data only. NLM periodically deletes its Web logs. On occasion, NLM may provide aggregated information to third party entities it contracts with for the purposes of research analysis. Aggregated data cannot be linked back to an individual user.

If your electronic medical record (EMR), patient health record (PHR) or other system links you to MedlinePlus, your diagnosis codes or other information, such as medications or procedures names, are sent to our site in order to link you to the most appropriate information. No personally identifiable information is collected in this process. We may review information in order to make improvements to our site and better meet user needs, but such information is reviewed at an aggregated level.


When you visit any Web site, it may place a small text file, known as a "cookie" on your computer. The cookie allows the Web site to "remember" specific information about your visit while you are connected or when you return to that site. The Office of Management and Budget Memo M-10-22, Guidance for Online Use of Web Measurement and Customization Technologies (PDF*, 1.03MB), 6/25/10, allows Federal agencies to use session and persistent cookies, defined below.

The cookie makes it easier for you to use the dynamic features of Web pages. Cookies from NLM Web pages only collect information about your browser's visit to the site; they do not collect personal information about you. While visiting certain NLM sites, you may occasionally encounter a Web page that automatically employs cookies to make it easier to use the dynamic features of these Web pages.

NLM Web sites may use either single session (temporary) or multi-session (persistent) cookies. Session cookies last only as long as your Web browser is open. Once you close your browser, the cookie disappears. Persistent cookies are stored on your computer for longer periods.

Session Cookies: We use session cookies for technical purposes such as to enable better navigation through our site. The OMB Memo 10-22 Guidance defines our use of session cookies as "Usage Tier 1 – Single Session." This tier encompasses any use of single session Web measurement and customization technologies.

Persistent Cookies: NLM uses persistent cookies to enhance the Web experience for our users. Persistent cookies remain on your computer between visits to NLM until they expire. The OMB Memo 10-22 Guidance defines our use of persistent cookies as "Usage Tier 2 – Multi-session without Personally Identifiable Information (PII)." This tier encompasses any use of multi-session Web measurement and customization technologies when no PII is collected.

For example, NLM uses persistent cookies to enable a PubMed retrieval system feature called "MyNCBI." The persistent cookie retains user preferences such as search result filters, LinkOut displays, institutional icon links, document delivery services, etc. across user sessions. Users may opt out of the persistent cookie selection in their MyNCBI settings at any time. NLM also uses persistent cookies to avoid repeated invitations to take the American Customer Satisfaction Inventory (ACSI) survey. The persistent cookies that block repeated survey invitations expire in 90 days. NLM may employ persistent cookies in other ways consistent with our mission and the OMB guidelines to analyze use patters and improve our users' experience on NLM Web sites.

How to Opt Out or Disable Cookies

If you do not wish to have session or persistent cookies placed on your computer, you can disable them at any time from your Web browser. If you opt out of cookies, you will still have access to all information and resources at NLM, but may be unable to use cookie-dependent features. Follow these instructions for disabling or opting out of cookies in the most popular browsers, Please note that by disabling cookies from your Web browser, you will disable cookies from all sources, not just those from NLM.

Personally Identifiable Information (PII)

If you choose to send us personal information by email, or by filling out a form on our Web site, we use that information to respond to your message and to help us provide you with information or material that you request. If provided, personally identifiable information is maintained in a database that is regularly purged. Third party contractors may have access to this information in order to provide a response to your question or comment. These contractors are held to strict policies to safeguard the information and provide the same level of privacy protection as guaranteed by NLM. On occasion, we may conduct a study concerning the types of questions sent to us. These studies help us to improve our Web sites in order to make them more responsive to the needs of our users. We do not give, share, sell, or transfer any personal information to a third party unless required by law.

Links to Other Sites

Some NLM Web sites, such as MedlinePlus, provide links to other Internet sites that provide health information. Once you link to another site, you are subject to the privacy policy of the new site.


The U.S. Government maintains this site. For site security purposes and to ensure that this service remains available to all users, we use software programs to monitor traffic to identify unauthorized attempts to upload or change information, or otherwise cause damage. Causing damage to federal computer systems is a violation of U.S. law and is subject to criminal prosecution in federal court. In the event of authorized law enforcement investigations, and pursuant to any required legal process, information from NLM Web logs may be used to help identify an individual.

Third-Party Web Sites and Applications

Third-Party Web sites and Applications (TPWA) are Web-based technologies that are not exclusively operated or controlled by NLM. They may be hosted on a non-government Web site or embedded on an NLM Web page. TPWA technologies may make personally identifiable information (PII) available to NLM, regardless of whether we request or collect it. In addition, other official Government Web sites we link to or cooperate with may use a third-party to handle some aspect of an information collection (for example: contest nomination process). As a result, our stated privacy policy/notice may not apply. 

We use these technologies to communicate and interact with you. Examples include social media Web sites such as Twitter and Facebook. Your activity on these non-government sites is governed by the security and privacy policies of those sites. When you use them, you are often sharing information with the general public, other users, and/or the group operating that site or application. We recommend you review the privacy policies of these sites before using them to ensure you understand how these third-party sites and applications might use your information. You may be able to adjust the privacy settings on your account.

The list below includes the applications we use and their purposes. For any sites or applications that collect PII, this list also includes details on the information they collect and how NLM protects your private information. 


AddThis allows you to bookmark and share NLM content in a variety of ways, including through social media sites and your Web-based email service. You do not need to register or provide any personal information to use AddThis.

The AddThis service collects non-personal data, including aggregate and summary statistics on Web browsers and usage patterns. AddThis also uses non-personal data to manage their service efficiently and diagnose server problems. Although AddThis offers some analytics and usage data to NLM, these reports do not include any personally identifiable information. The reports are password protected and only available to NLM managers, members of the NLM Web Teams, and other designated NLM staff requiring this information to perform their duties. The AddThis Privacy & Data Practices are available at:

Go.USA.Gov and

NLM uses the and URL shortening services. The shorter URLs are shared in our e-mail messages, Twitter feeds, and on NLM's Facebook pages. The services collect data about how often users click on these shortened URLs. The analytics data is provided by Go.USA.Gov and This data does not provide any personally identifiable information about the visitors who opened NLM's shortened links. The Go.USA.Gov Privacy Statement is available at The Privacy Policy is available at:


NLM has multiple Facebook pages where we share information about NLM news, program activities, and other items that may be of interest to you. You do not need to register or provide personal information to view our Facebook pages. The complete list of NLM Facebook pages is at

If you have a Facebook account and "Like" NLM Facebook pages, you may post comments or click the "Like" link for individual entries. If you comment on or "Like" NLM Facebook content, personally identifying information will be visible to other Facebook visitors, including NLM staff. The amount of visible personal information about you will depend on your own Facebook privacy settings. To avoid displaying your personally identifiable information, you should not create a Facebook account, post comments or click on the "Like" options in Facebook.

NLM does not collect, use or disclose any information about visitors who comment on or "Like" NLM Facebook pages. Facebook collects and reports non-personally identifiable information about activities on NLM's Facebook pages. This information is password protected and only available to NLM managers and the administrators of the NLM Facebook pages, who require this information to perform their duties. The Facebook Privacy Policy is available at:


NLM uses GovDelivery to manage email subscriptions for its electronic newsletters, email alerts and other messages about NLM products and services. To subscribe to Gov Delivery for NLM updates, you must provide an email address and indicate your subscription preferences, including the NLM products and type of updates you would like to receive.

GovDelivery collects non-identifiable information about the number of messages sent, how often people open the email messages and whether they click on the links in messages. This information is provided to NLM managers on GovDelivery's password protected Web site. It is only available to NLM managers and staff who manage the email subscription lists as part of their regular duties. The GovDelivery Privacy Policy is available at:

iTunes App Store

NLM uses iTunes to make iPhone, iPod and iPad apps available for download through the Apple's App Store. A list of NLM apps is available at You do not need to register or provide personal information to view the NLM app in the App Store. If you use the iTunes application to view information about NLM apps, iTunes collects information specified in its privacy policy.

If you have an iTunes account and download an app, you may rate or review the app.  If you review an NLM app, your personally identifiable information will be visible to other iTunes visitors, including NLM staff. The amount of visible personal information will depend on your account settings. To avoid displaying your personally identifiable information, you should not create an iTunes account, download apps, or post ratings.

NLM  does not collect, maintain, disclose, or share any information about people who download NLM apps. Apple collects and provides non-identifying information on  how many times an app is downloaded and the continent it is downloaded from. This information is password protected and only available to NLM managers and the administrators of the NLM iTunes apps, who require this information to perform their duties. The iTunes privacy policy is available at:


NLM uses Twitter to send short messages (up to 140 characters), which are also known as "Tweets," to share information about NLM news, program activities, and other items that may be of interest to you. We also respond to comments and questions sent via Twitter to NLM. You do not need to register or provide personal information to view our Twitter feeds. A complete list of NLM Twitter feeds is available at:

If you want to subscribe to (also known as "Follow") the NLM Twitter feeds, you may create a Twitter account at To create an account, you must provide your name and email address and create a user name and password. You may provide additional information including a short biography, location or a picture. Most of your personal information in your Twitter account is available to the public unless you update your privacy settings.

NLM staff monitor the number of subscribers (known as "Followers") and respond to their comments and queries via Twitter, but we  do not track the personal information of our Twitter followers. NLM does not collect, maintain, disclose or share any information about people who follow NLM on Twitter. The Twitter Privacy Policy is available at:

*PDF documents require the use of the Adobe® Reader, which can be downloaded from the Adobe Web site at no charge.