It won’t be long before smartphones will be as familiar as thermometers in family health tool kits. Smartphones, with their powerful built-in computers, may in fact become more familiar as increasing numbers of people use them to measure and track blood pressure, heart rate, blood glucose, hormone levels and yes, temperature.

User-friendly smartphone technology will cause “the biggest shakeup in the history of medicine,” Dr. Eric Topol, director of the Scripps Translational Science Institute in La Jolla, Calif., said in an interview with MedScape, a website for health professionals. Patients can get some of their own test results—no lab visit required—using sensor devices that interact with their smartphones. They can immediately measure and track how lifestyle changes or medication affect their health. They can share that data with their doctors, or online health-focused social networking sites like www.patientslikeme.com and www.CureTogether.com, which have developed databases  on what’s helped—and not helped—a variety of health concerns.

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Topol has his patients send screenshots of blood pressure readings from smartphone prior to appointments. The Finnish-developed Beat2Phone allows patients to take electrocardiograms at home and send results immediately to their doctors (though these results are not yet as comprehensive as those from laboratory or hospital tests). There are apps to detect seizures and strokes; apps to manage weight loss and diabetes; take photos of the interior of the eye; tell you what kind of a skin rash you have.

The Centre for Global eHealth Innovation of the University Health Network in Toronto has designed a smartphone application that warns asthmatics of weather that could cause breathing problems. At the University of Utah, researchers have developed a device that measures cortisol concentration in saliva, an indication of stress levels or early warning of adrenal disease. The test will cost about $5 and take 10 minutes and can be communicated immediately, a fraction of the cost of lab tests and their turnaround time.

The market is flooded by consumer medical software applications—there are close to 20,000—and devices that interact with smartphones. The Scanadu Scout, which retails for about US$150, measures vital signs so patients can see effects of medications or lifestyle changes, and track them over time. This allows them to see what works for them specifically, and allows them to spot problems before they become serious.

Also in development are test strips for home urinalysis, data that can be used to diagnose bladder infections or monitor how diabetes is affecting the kidneys, and test strips that can analyze saliva for flu strains or strep throat.

Patient involvement is only half of the picture—smartphone technology, when combined with social networking, promises to change how new pharmaceuticals get to market, particularly shortening time from discovery until it’s available at the pharmacy.

Crowdsourcing—soliciting contributions from a large group of people, usually online—could expand the population for clinical trials and allow constant monitoring of adverse effects. It has already been used to raise funds for medical devices to be used with smartphones, and to test them.

We’ve entered an age of patient-driven research. In 2008, patientslikeme.com found no evidence lithium treatment for ALS (Lou Gehrig’s disease) helped 300 of its members, research results repeated two years later by the U.S. National Institutes of Health.

“What if we could learn from the collective experience of patients everywhere?” is the greeting on www.crohnology.com. From data collected since 2011 from thousands of members with Crohn’s disease, an inflammatory bowel disease, the site reports best results have come from giving up beer, followed by the use of vitamin D and the pharmaceutical prednisone. But it also records everything anybody has tried, from prescription medication to alternative therapies.

San Francisco software developer Sean Ahrens came up with the idea after trying an alternative treatment—ingesting parasitic worms. Self-treatment provides valuable first-hand medical data not captured by doctors or researchers—but that could be captured with technology. He points out a million patients could not be seen by one doctor or followed in one clinical trial—but modern technology makes it possible to collect and crunch that much data. Now he plans sites for multiple sclerosis and rheumatoid arthritis.

Devices on the market now are criticized as less accurate or comprehensive than lab or hospital tests, but they undoubtedly will improve. The bigger question is if smartphone medical applications will live up to their promise. Will patients become more informed—or more misinformed? Will new devices cut down on unnecessary doctor visits, replace expensive lab tests and empower patients with data and knowledge about their health? Or will they create new problems—increasing misdiagnosis, giving patients a false sense of security, deluging doctors with reams of patient-generated information?

Topol is optimistic. Doctors no longer have a monopoly on knowledge and patient data; when patients, armed with data, ask their doctors to be a partner in their healthcare “that could set off a whole different way of practising medicine in the future.”