(CNN) Social media instantly brings us together to share our thoughts, feelings and experiences. And since a picture often says it best, up go those kid, pet and vacation photos.
But on various health communities across the internet, some people go much further -- uploading disturbing images of bumps or blisters on their genitalia in search of a crowdsourced medical diagnosis, according to a new study published Tuesday in JAMA.
At a time when the rates of many STDs are soaring, people are sharing images of genital sores and rashes with strangers on the internet.
After adding detailed descriptions of their symptoms, they ask others for a diagnosis. The answers often come within minutes.
"It's concerning if people are getting the wrong diagnoses or are being misled as to treatments, which certainly could be the case," said Dr. Eric Topol, the founder and director of the Scripps Research Translational Institute, who was not involved in the study.
"You wouldn't think STDs would be shared on social media, as it starts to get into matters of the utmost privacy," said Topol, adding that there is "no anonymity guarantee" on such websites.
"So while crowdsourcing is not new, this is surprising," he said. "It's noteworthy that there's this much going on."
Sharing health concerns occurs across many social media sites, including Facebook and Twitter. This study focused on the health communities on Reddit, a social media platform ranked as the 6th most visited website in the United States.
Reddit is organized by hundreds of topics, a good many focused on health. The study analyzed the Reddit STD community, called "r/STD," a rapidly growing group in which comments have doubled since November 2018.
"About 58% of posts to Reddit's r/STD were explicitly requesting a crowd-diagnosis," said co-author John Ayers, an associate professor in the Infectious Disease & Global Public Health division of the University of California San Diego.
"About 38% of the people asking for a diagnosis shared an image of their symptoms," Ayers said. The response rate was astonishing, he added: Nearly 90% received a reply, and quickly -- some within minutes, others within hours and almost all within a day.
The study found the diagnoses offered by the crowd are often "wildly inaccurate," while the types of treatments users recommended frequently went against doctor's orders.
"Apple cider vinegar cures all according to the crowd on social media," said co-author Alicia Nobles, a postdoc fellow in the division of Infectious Disease and Global Public Health at UC San Diego, in a statement.
Even more startling, the study found 20% of the people asked the crowd for a second opinion after a doctor had already diagnosed a sexually transmitted infectious disease and suggested treatment.
"One in five people who asked for a diagnosis actually want the crowd to explain how their doctor was wrong," Ayers said. "They wanted the crowd to tell them, 'No, that's an ingrown hair,' and not a distinct sign of genital herpes."
At times, a poster's denial can be dangerous, the study found. "We have one case in the paper where someone wanted his diagnosis of HIV to be rejected," Ayers said. "They wanted the crowd to explain how their doctor was wrong.
"Here's someone who knows they're infected but they're deluding themselves into thinking they're not, so they'll continue to be a risk to other people," he said.
Yale internist Dr. Lisa Sanders, host of the Netflix show "Diagnosis" and author of the New York Times Magazine column by the same name, told CNN she found the study's findings "concerning."
"It's one thing when doctors can't figure out what's wrong and you ask others for help," said Sanders, who was not involved in the study.
"But this is entirely different," she said. "These are not mysterious diagnoses. These are straight-up tests, usually blood tests."
Cases of gonorrhea, chlamydia and syphilis have reached the highest levels ever recorded, according to a recent report from the US Centers of Disease Control and Prevention.
Many men and women with STDs never have symptoms and have no idea they are infected. When symptoms do appear, they can differ widely from person to person, often masquerading as a benign bump.
Take syphilis, for example. Once nearly eliminated in the US, cases of syphilis are now rising yearly. Cases of congenital syphilis -- where a mother gives the disabling disease to her unborn baby -- have more than doubled since 2013.
Syphilis is easily diagnosed with a simple blood test and responds well to penicillin when caught early. Left untreated, it can cause serious and life-threatening damage to the nervous system, heart, brain or other organs.
"Syphilis is the perfect STD for people who thrive on denial," said family medicine physician and STD specialist Dr. Ina Park, "because it starts with a sore that doesn't hurt."
The bump can be very small, subtle and easily discounted, said Park, who is the medical director of the California STD/HIV-Prevention Training Center.
"If you see it and you do nothing about it, it just goes away. And then you get the rash. And then if you ignore the rash, it also goes away," Park said. "They just disappear and then you can just talk yourself out of the fact that you have this potentially deadly disease."
Why would people crowdsource a STD diagnosis? Lack of money to pay for medical services is one reason, experts say. Even when that's not an issue, it can be difficult to get a timely appointment with a doctor while the lesions are present.
"There is a lack of easy access in the US to same-day testing and treatment. I think there are some people who say, 'I just want an opinion now and this is a way to get it,' " Park said.
"We've also closed down a lot of places over the last 10 years where it was easier to get tested for STDs -- Planned Parenthood for example," Sanders said.
Sanders points out that asking our personal "crowd" of friends and family for health advice is completely normal behavior. "We've always asked mom, our friends and spouses if we should be concerned about this or that symptom," she said.
Then there's the very human desire to wish away the reality of a sexually communicated disease.
"There's so much stigma and shame attached to STDs I'm sure they would do anything to avoid having to address that if it's not true," Sanders said. "So I understand it, even though I might disagree with it."
However, Park added "for those who already have a medical diagnosis and are still seeking a second opinion through crowdsourcing, I do think it's potentially dangerous because you have no idea who's giving you this advice and their expertise."
Some experts believe crowdsourcing healthcare could be turned into a positive by training and educating what Topol calls the "citizen doctors out there willing to help each other."
"The automatic reaction of a lot of doctors would be: 'This crowdsourcing is nonsense and it should stop.' And that's where I disagree," Topol said.
"If this is helping some people who can't afford medical care or can't get to a diagnosis in a timely way, I don't know that we should definitely rule it out as a pathway for health care," Topol added. "But we also want to assure its accuracy, and point out to people that the diagnosis you get from Dr. Reddit may not be right."
Ayers agrees: "People are already seeking help in these social media communities, so why not take the education to them? It happen in a place that you can potentially easily intervene and guide them to good health."