Health information on the Internet refers to all health-related information communicated through or available on the Internet.

The Internet is widely used by the general public as a tool for finding health information. In the late 1990s, researchers noted an increase in Internet users' access to health-related content despite the variation in the quality of information, level of accessibility, and overall health literacy. Access to health information does not guarantee understanding, as health literacy of individuals vary.

It is believed patients who know their medical history may learn and interpret this information in a way that benefits them. This, however, is not always the case because online health information is not always peer reviewed. Physicians worry that patients who conduct Internet research on their medical history are at a risk of being misinformed. In 2013, the opinions about the relationship between health care providers and online health information were still being established. According to a 2014 study, "The flow of information has fundamentally changed, and physicians have less control over health information relayed to patients. Not surprisingly, this paradigm shift has elicited varied and sometimes conflicting views about the value of the Internet as a tool to improve health care."

In cases in which a physician has difficulty explaining complicated medical concepts to a patient, that patient may be inclined to seek information on the internet. A consensus exists that patients should have shared decision making, meaning that patients should be able to make informed decisions about the direction of their medical treatment in collaboration with their physician. Rich, educated, and socially advantaged patients may enjoy the benefits of the shared decision-making approach more than those with a lower socioeconomic class or minority status.

Patients' naive understanding of their health contributes to a range of issues, including the tendency to deviate from the physician's medical advice or to miss medical appointments. Patients with limited access to health information are more likely to use complementary and alternative medicine, and fail to inform their physician about it. Complementary and alternative medicine may not be evidence-based medicine. While physicians can work on improving their doctor-patient communication skills, individuals can become more knowledgeable about their health through patient education programs. A study by Lorig in 2002 suggested healthcare processes can be efficiently improved with patients' behavior.

Social forums in which anyone can have conversations about health with their peers exist; these are especially popular among patients who want to talk about shared medical concerns with others. Those who participate in online communities that discuss health issues report feeling relieved about their health worries, perceiving they have more control over their health and medical condition, gaining more medical knowledge, and having more personal agency overall.

Some research studies have failed to find evidence to validate the physicians' concerns about patients receiving misinformation online or using online health information to conduct self-diagnosis. Patients with chronic diseases who use the Internet to get health-related information often acquire good skills to judge the quality of information that they find.

Social media platforms are considered channels physicians can use to acquire insight on their patients' thoughts. Patients have increasingly turned to social media for health information, sometimes of dubious quality. Several studies have used social media to gather data on patients' adverse drug reactions (ADRs) with generally promising results.