State health officials conceded Friday night that six Massachusetts patients suffering from probable cases of vaping-related lung illnesses may have used illicit marijuana vapes in addition to legal ones, a surprising revision from the day before when officials suggested products sold at licensed cannabis retailers were to blame for the ailments.

The admission, along with a Friday agreement by the state Department of Public Health to release detailed information about the cases to the state Cannabis Control Commission, headed off a highly unusual public confrontation between the two Massachusetts agencies.

But the deal prohibits any immediate public release of the data, meaning uncertainty about the real cause of the six cases could linger for weeks or longer. Along with earlier conflicting warnings from health officials, the latest back-and-forth promises to further bewilder consumers about which vaping products are safe and which might make them sick. It also risks undermining confidence in the ability of Massachusetts authorities to manage a fast-evolving public health crisis.

Earlier Friday, the cannabis commission urged health officials to identify the licensed cannabis producers that made the vapes tied to the six cases, saying it is “critical to expediting the Commission’s investigation into potential legal sources of those products, and for the public to fully understand whether products they have purchased may be linked to any probable injuries.”

Now, health department officials say they have signed an agreement with the commission, an independent state agency, to share information, and handed over the names of the implicated cannabis companies and products and other details .

A commission spokeswoman Friday said the agreement will help the agency “determine whether any items sold by Massachusetts licensees may be implicated” in the lung illnesses, and pledged to “keep the public informed as to whether any legal products are confirmed to be linked to these illnesses.”

But some public health experts said the state has been opaque in its handling of the vaping crisis.

“Consumers are really left in the dark today as to how to protect their health,” said Jane Allen, a longtime researcher at RTI International who specializes in developing and evaluating public health policies and messaging. “It’s the responsibility of the [commission] and the [health department] to convey any information they have to the public so people can choose how best to protect themselves.”

The health department, for its part, would say only that “at least one” of the six patients had used an illicit marijuana vape in addition to a regulated one.

The health department first reported on Thursday night that six patients with probable — but not confirmed — cases of vaping-related lung illness had told investigators they used vapes from licensed marijuana retailers. (In those vaping cases labeled as “probable,” health professionals suspect vaping is a major reason for the symptoms but haven’t ruled out other possible contributing factors.) The report also listed a number of vape brands used by lung-illness patients, but did not identify which were legal and which were illicit.

The six patients who said they used legal vapes are a fraction of the 90 confirmed and probable cases of vaping-related lung illnesses that Massachusetts has reported to federal health officials. However, officials interviewed patients in only 49 of the 90 cases, and some reported using only nicotine vapes. A further 22 patients used marijuana vapes not purchased at legal shops here.

According to the US Centers for Disease Control, vitamin E acetate and other dangerous additives commonly found in illicit vapes — but rarely used in regulated products — account for most of the nearly 2,300 illnesses documented so far across the United States.

The revelation Thursday by the health department followed weeks of pressure from regulators and consumers to be more forthcoming about which vaping products have sickened Massachusetts consumers.

Other states that have legalized cannabis in some form have said regulated recreational and medical marijuana products are not to blame, cracked down on illicit suppliers, and published the names and pictures of illegal marijuana products used by lung patients so consumers can avoid them. But the Massachusetts health department initially denied having such information, and later claimed it was protected by patient privacy rules, even as critics said the information could be easily anonymized.

That changed with the publication of the analysis Thursday; then on Friday officials provided incomplete answers about whether the six patients had also used illicit vapes.

Public health experts said much remains unclear, and they implored health officials to publicly release everything they know about a possible link between legal marijuana vapes and the lung illnesses.

“It appears [the health department] has finally heard the complaints and decided to release some measure of information. It’s long overdue,” said Leo Beletsky, a professor of law and health sciences at Northeastern University who specializes in drug policy and harm reduction.

But, he added, “It’s ambiguous and unclear and not actionable. It seems designed to reinforce the conclusion that this entire class of products is dangerous. We have to have more information.”

Beletsky and other experts said the recent reports leave unclear exactly how many of the patients who used regulated vapes had also used illicit ones; nor, they said, have officials made clear which vape brands were linked to which types of cases — probable or confirmed.

Public health experts also noted it was highly likely some patients would lie about where they obtained marijuana vapes for fear of prosecution, for example, or deportation.

Other flaws in the report cited by experts who reviewed it include the poor sample size: There are no data for nearly half of the cases.

“From a public health perspective, this is a terrible response rate,” Allen explained. “In any kind of survey work, those who don’t respond or are excluded are often excluded systemically, so their exclusion biases the results. ”

A spokeswoman for the Department of Public Health noted that some patients have been reluctant to candidly discuss their use of products that may have been obtained from an illegal source, while others are too sick to provide information. She said the state is working to interview the remaining patients.