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NLM Director’s Comments Transcript
Internet Search Provides Early Warning of Drug Interaction: 05/13/2013

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Greetings from the National Library of Medicine and

Regards to all our listeners!

I'm Rob Logan, Ph.D. senior staff National Library of Medicine for Donald Lindberg, M.D, the Director of the U.S. National Library of Medicine.

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A novel Internet search (based on six million users) discovered harmful side effects from taking two prescription medicines — prior to safety warnings from the conventional, physician-based reporting method used by the U.S Food and Drug Administration (the FDA). The pioneering study recently was published in the Journal of the American Medical Informatics Association.

In an analysis the study’s four authors call pharmacovigilance, the research found Internet users searched for information about high blood sugar levels when they simultaneously took a prescription antidepressant (paroxetine) and a cholesterol-lowering drug (pravastatin). The researchers assessed one year of search history from six million Internet users, who agreed to share anonymous logs of their web searches.

By searching through their logs, the researchers identified a possible negative drug interaction before the FDA’s physician-based adverse event (or side effect) reporting system.

One of the study’s five authors told the New York Times the research’s intent was to discern the capabilities of data mining tools to identify adverse drug interactions based on the Internet inquiries people make about prescription medicines. In their study the authors write (and we quote): ‘we hypothesized that Internet users may provide early clues about adverse drug events via their online information-seeking’ (end of quote).

The authors applied automated tools to look for patterns among the drug, symptom, and condition information from the 82 million individual searches conducted by the study’s participants.

Specifically, the researchers found Internet users who searched for information about paroxetine and pravastatin also looked for terms associated with blood sugar levels. The authors, then, calculated the likelihood that users in each group searched for words akin to hyperglycemia (such as ‘high blood sugar’) as well as 80 of its symptoms (such as ‘blurry vision’).

The study found Internet users who searched for both paroxetine and pravastatin were significantly more likely to search for an array of terms associated with ‘blood sugar’ compared to persons who searched for just one of the two drugs.

The authors explain patterns among consumer inquiries about health risks represent what they call ‘signals.’ The authors write (and we quote): ‘The prolific use of web search to pursue information can be likened to a large scale distributed network of sensors for identifying the potential side effects of drugs. There is a potential public health benefit in listening to such signals and integrating them with other sources of information’ (end of quote).

The authors explain the research about Internet use patterns might be used to compliment traditional medication safety surveillance efforts. For example, the Times notes research similar to the current study might supplement the FDA’s Sentinel Initiative, which uses information from health care providers to find unreported health risks among approved medications.

The study’s authors add they did not assess if there were significant demographic patterns among the Internet users who searched for information about paroxetine and pravastatin. However, they suggest more understanding about how age, income, and other demographic variables predict how frequently persons search for information about drug risks might boost similar, future research efforts.

Meanwhile, a good introduction to Med Watch, the FDA’s current side effect or adverse event drug reporting system, is provided (by the FDA) within the ‘law and policy’ section of’s drug reactions health topic page. A helpful and easy-to-read introduction to avoid harmful drug interactions also is provided by the FDA in the ‘start here’ section of’s drug reactions health topic page.

You also can search for information about the side effects of individual medications within’s ‘drugs and supplements’ section. For example, the section explains the side effects as well as provides patient safety information about paroxetine and pravastatin.’s drug reactions health topic page additionally contains links to the latest pertinent journal research articles, which are available in the ‘journal articles’ section. Links to related clinical trials that may be occurring in your area are available in the ‘clinical trials’ section. From the drug reactions health topic page, you can sign up to receive email updates with links to new information as it becomes available on MedlinePlus.

To find’s drug reactions health topic page, just type ‘drug reactions’ in the search box at the top of’s home page. Then, click on ‘drug reactions (National Library of Medicine).’ To find’s drugs and supplements section (which provides safety information on individual medications), just click on ‘drugs and supplements’ towards the top of’s home page.

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