The Drugs That Power Silicon Valley.

Magic Mushrooms. LSD. Ketamine. 

Entrepreneurs including Elon Musk and Sergey Brin are part of a drug movement that proponents hope will expand minds, enhance lives and produce business breakthroughs

Elon Musk takes ketamine. Sergey Brin sometimes enjoys magic mushrooms. Executives at venture-capital firm Founders Fund, known for its investments in SpaceX and Facebook, have thrown parties that include psychedelics.

Routine drug use has moved from an after-hours activity squarely into corporate culture, leaving boards and business leaders to wrestle with their responsibilities for a workforce that frequently uses. At the vanguard are tech executives and employees who see psychedelics and similar substances, among them psilocybin, ketamine and LSD, as gateways to business breakthroughs.

“There are millions of people microdosing psychedelics right now,” said Karl Goldfield, a former sales and marketing consultant in San Francisco who informally counsels friends and colleagues across the tech world on calibrating the right small dose for maximum mindfulness. It is “the fastest path to opening your mind up and clearly seeing for yourself what’s going on,” said Goldfield.

Goldfield doesn’t have a medical degree and said he learned to dose through experience. He said the number of questions he gets about how to microdose has grown dramatically in recent months.

The account of Mr. Musk’s drug use comes from people who witnessed him use ketamine and others with direct knowledge of his use. Details about Mr. Brin’s drug use and the Founders Fund parties come from people familiar with them.

Musk, his attorney and a top adviser didn’t respond to requests for comment. A spokeswoman for Brin, the co-founder of Google, didn’t respond to requests for comment.

The movement isn’t a medical experiment or a related investment opportunity, but a practice that has become for many a routine part of doing business. It comes with risks of dependence and abuse. Most of the drugs are illegal. Before he was killed in April in San Francisco, Bob Lee, the founder of CashApp, was part of an underground party scene known as “the Lifestyle,” where the use of psychedelics was common. Lee had ingested drugs including ketamine before his death, an autopsy showed.

Silicon Valley has long had a tolerance toward drug use—many companies don’t test employees regularly—but the phenomenon is worrying some companies and their boards, who fear they could be held liable for illegal activity, according to consultants and others close to the companies.

Users rely on drug dealers for ecstasy and most other psychedelics, or in elite cases, they employ chemists. One prolific drug dealer in San Francisco who serves a slice of the tech world is known as “Costco” because users can buy bulk at a discount, according to people familiar with the business. “Cuddle puddles,” which feature groups of people embracing and showing platonic affection, have become standard fare.