In summary

Thomas Cowan, a purveyor of debunked theories, can no longer practice medicine in California. He plans to become an “unlicensed health coach.”

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For the record: An earlier version of this article referred incorrectly to the conditions of Cowan’s medical board probation. The conditions state that he may request voluntary surrender of his medical license if he stops practicing medicine.


A San Francisco doctor infamous for spreading misinformation linking COVID-19 to 5G communications networks can no longer practice medicine after surrendering his license to California’s medical board. 

Until last July, Thomas Cowan ran an alternative medicine practice that didn’t accept insurance, sold nutritional supplements and offered $375 consultations. Cowan has published several fringe medicine books — including one questioning whether viruses cause disease — that rank highly on searches for vaccine books on Amazon and bookseller Barnes and Noble. 

Thomas Cowan, M.D. Photo via Twitter

The medical board in 2017 had placed Cowan on a 5-year probation for prescribing unapproved medications to a breast cancer patient.

Cowan wrote on his website that he closed his practice June 30 and would “relinquish” his license with plans to reemerge as an “unlicensed health coach.” He would move to the East Coast to be near family and would continue to sell herbal supplements online, he added. He could not be reached for comment today. 

“I simply see too much to be willing to function as a physician in the medical system at this time,” Cowan wrote. “I will no longer be able to order tests, write prescriptions, make diagnoses or offer treatment plans…I am looking forward to a new way of interacting with my friends, previously known as patients.” 

Cowan surrendered his license on Dec. 7 according to medical board documents. The state agency, which regulates and disciplines California doctors, made the license surrender public on Thursday. 

Cowan first publicized his discredited theory that 5G internet networks cause COVID-19 in a YouTube video that went viral last March. YouTube removed the video as part of its effort to crack down on pandemic misinformation — but not until it was amplified by celebrities with large social media followings, including Woody Harrelson and John Cusack.

Despite numerous debunkings by public health experts, the 5G pandemic conspiracy theory has taken hold worldwide and has proven particularly hard to combat. It has had real-world effects: numerous attacks on 5G towers have been reported in Europe and Latin America. The World Health Organization notes on its “mythbusters” website that the novel coronavirus that causes COVID-19 cannot travel over radio waves or mobile networks. COVID-19 cases have been reported in countries that do not yet have 5G. The misguided attempt to link the pandemic to telecommunications networks grows out of larger fears that 5G could increase cancer risk. No evidence exists for such a link, public health experts say.

Cowan is one of numerous health professionals who used medical credentials to put forth false theories during the coronavirus pandemic.

Conspiracy theories like Cowan’s erode public trust, create confusion, and undermine public health, said Anne Rimoin, a UCLA epidemiologist.

“Social media amplifies misinformation in a way we’ve never seen before,” Rimoin said. “These theories not based in science now have a conduit to get out to the world so easily. When you have confusion, people make bad decisions and we have to divert precious resources towards stamping out misinformation. It doesn’t just hurt the believer. It hurts everybody.”

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Barbara Feder Ostrov

Barbara Feder Ostrov, Contributing Writer for CalMatters, has reported on medicine and health policy for more than 15 years. She most recently covered California and national health issues for Kaiser Health...