“Untested, deceptive treatments” can endanger consumers, Internet giant says.

Responding to ubiquitous online marketing by stem cell clinics selling unapproved treatments for everything from achy joints to Alzheimer’s, Google announced Friday it will no longer accept ads for “unproven or experimental medical techniques,” including most stem cell therapy, cellular therapy and gene therapy.

The Internet giant said it was taking the step after seeing “a rise in bad actors” trying to take advantage of patients by offering “untested, deceptive treatments.” Often, Google said in a post explaining the new policy, “these treatments can lead to dangerous health outcomes and we feel they have no place on our platforms.” Its new policy will prohibit ads for treatments that have “no established biomedical or scientific basis.”Desperate for a cure, she turned to stem cell injections. Now she’s blind.Doris Tyler, 77, went blind in 2016 after receiving unapproved stem cell injections in her eyes.

The new position comes as stem cell clinics have grown into a sprawling direct-to-consumer industry. Some clinics have told patients their treatments can help them with ailments such as macular degeneration, ALS, multiple sclerosis and degenerative lung diseases. Scientists and medical associations have likened the procedures to modern snake oil and accused the purveyors of preying on the hopes of seriously ill patients. The untested treatments, many researchers say, is imperiling patients and the reputation of a promising field.

After years of little enforcement, the federal regulators have begun to crack down on the clinics. And the new Google policy will add to the growing scrutiny and pressure, industry experts said.

When asked by The Washington Post last December about its policies about advertising by stem cell clinics, Google declined to answer questions about actions against specific companies. In a statement, the company said: “If we find ads that violate our policies, we take immediate action, which can include taking down violating ads or suspending an account altogether.”

At the time, the company said its existing policies already prohibited marketing potentially dangerous and fraudulent health products — a stance some stem cell experts criticized as insufficient.

“Google’s new policy banning advertising for speculative medicines is a much-needed and welcome step to curb the marketing of unscrupulous medical products,” said Deepak Srivastava, president of the International Society for Stem Cell Research, a leading group of scientists that gave Google advice on the policy. “The premature marketing and commercialization of unproven stem cell products threatens public health, the confidence in biomedical research, and undermines the development of legitimate new therapies,” he said.

Some treatments have resulted in severe injuries, including at least five women who were blindedafter stem cell clinics injected its product into their eyes.

Stem cell clinics say they are offering treatment to patients who have few other options and that their treatment may have ways of helping patients that science can’t yet explain.

Some industry representatives criticized Google’s new ad policy on Friday. The ban on ads will unfairly devastate “good” companies along with “bad actors” without discriminating which ones are trying to treat patients safely and follow evolving FDA regulations, said Andrew Ittleman, a Miami lawyer who represents several stem cell clinics.

In the past two years, Google had already begun refusing ads from several stem cell companies on a case-by-case basis, said Ittleman, who has been hired by a few such companies to try, unsuccessfully, to appeal such decisions with Google.

“It puts Google in the position of being a quasi regulator, taking on quite a significant amount of jurisdiction,” Ittleman said. “They’re painting the industry with a broad brush and companies with legitimate arguments are going to be collateral damage.”

Google’s new ad policy, however, is unlikely to put the industry out of business. Many clinics have shown an ability to adapt nimbly to new regulatory rules and changes such as Google’s ad policy.

“This kind of ad ban hits hard because most companies rely on Google for a large share of their quality sales leads,” said a former marketing head for a Florida stem cell company. “But there are plenty of other channels you can switch to — Facebook, Bing, Yahoo, YouTube.”

The marketing executive, who spoke on the condition of anonymity to avoid professional retaliation, said “These kinds of businesses are pretty savvy and have had to adapt a lot already. Many have previously been kicked off Google already. You learn to pivot and be resourceful.”

Another recent example of the industry’s ability to adapt, experts note, came when the Food and Drug Administration won a landmark lawsuit in June against a stem cell company selling stem cell procedures that extract clients’ fat tissue, spin it to isolate certain cells, and inject them back into the body.

Health officials hailed the case as a turning point in the government’s struggle to regulate the booming industry. But ahead of the legal victory, the industry had already begun to shift. Because the FDA was focusing on fat-based treatments, many clinics switched to treatments derived instead from s blood, bone marrow and birth-related tissues, such as amniotic fluid and umbilical cord blood.

Google officials said Friday they would continue to accept ads for clinical trials cleared by the government. It said that while important medical discoveries often start as unproven ideas, “we believe that monitored, regulated clinical trials are the most reliable way to test and prove important medical advances.”

The ban will take effect across Google’s ad services, including YouTube and ads Google helps place on third-party websites. And the ban includes treatments that are rooted in scientific findings and preliminary clinical experience “but currently have insufficient formal clinical testing” to justify widespread use. The new policy, which will take effect in October, was detailed in a blog post by Adrienne Biddings, the company’s policy adviser.

The post said that the “digital ads ecosystem can only flourish if it’s a place that is safe and trustworthy for users.” The company said it will use a combination of machine learning and human review to enforce it.

To formulate the new approach, a spokeswoman said, the company’s policy team has reviewed the literature on the field and worked with various stem-cell experts.

Paul Knoepfler, a stem cell biologist at the University of California at Davis and longtime critic of the for-profit stem cell industry, called the new Google policy a big deal. Many patients who have been seriously harmed, he noted, were initially recruited as customers via Google ads.

“A number of us have pushed for this kind of policy over the years so this news is a welcome surprise,” Knoepfler said.