In a rare public rebuke of the nation’s largest retail pharmacy chain, state regulators in Oklahoma cited and fined CVS for conditions found at four of its pharmacies, including inadequate staffing and errors made in filling prescriptions.

While the fine of $125,000 on Wednesday was small for CVS Health — it paid its chief executive $36.5 million in total compensation last year and is the country’s fifth-largest company — the move validated concerns raised at multiple drugstore chains across the country by pharmacists and technicians who say understaffed workplaces are putting the public at risk.

CVS also agreed to distribute a memo to its pharmacists in the state, highlighting a law that requires them to take action if working conditions in their pharmacies could lead to problems safely filling prescriptions. The memo is to make clear that they are not to face retaliation for documenting and reporting such issues.

In a statement, a CVS spokesman said the company agreed to the terms to “avoid the time and expense of a protracted hearing process and to foster a positive working relationship” with the Oklahoma State Board of Pharmacy. The spokesman said the action did not constitute an admission of guilt by the company on all counts.

The state board inspected the four pharmacies from mid-2019 to early this year after receiving multiple complaints about errors and overwhelmed staff members.

One of those errors occurred last year when a developmentally disabled teenager received one-fourth of his prescribed dose of anticonvulsant medication from a CVS in Owasso, a suburb north of Tulsa, according to a complaint filed by the board. The boy took the incorrect dosage for 18 days, during which his seizures became uncontrollable, causing him to fall and hit his head, said his father, Aron Brown.

The convulsions were “nonstop” and “violent,” Mr. Brown said. “You have no idea what kind of shame we feel about this — that we couldn’t figure out what was going on.”

As part of its agreement on Wednesday, CVS will pay a $75,000 fine for that incident — the highest amount allowed under state law for this case — and its Owasso pharmacy will remain on probation for two years. While pleased the board had addressed the matter, the boy’s parents said they were worried that the action was not strong enough, and that it could allow other patients to be harmed in the future unless CVS made substantial changes to its business.

“A $75,000 fine? That is nothing to them,” said the teenager’s mother, Rachel Banning. “These things are going to keep happening if they don’t fix their staffing issues.”

Pharmacists in dozens of states have accused CVS, Walgreens and other major pharmacy chains of putting the public at risk of medication errors because of poorly staffed and chaotic workplaces, The New York Times reported in January.

In letters to state pharmacy boards and in interviews with The Times, pharmacists said they struggled to keep up with an increasing number of tasks — filling prescriptions, giving flu shots, tending the drive-through, answering phones and calling patients — while racing to meet corporate performance metrics they characterized as excessive and unsafe.

The pharmacy chains, including CVS, have pushed back on employees’ complaints, saying staffing is sufficient and errors are rare.

Most state investigations focus on pharmacists, not conditions in their workplaces. In Oklahoma, the state board has begun investigating broader workplace issues when responding to complaints and doing routine inspections.

In mid-January, two board compliance officers went to a CVS in Bartlesville, Okla., to investigate a complaint of a mislabeled prescription. There, they “witnessed a chaotic scene including the phones ringing almost all of the time, along with constant foot traffic and drive thru traffic,” according to a complaint filed against CVS.

The officers discussed the error with the head pharmacist, noting that she said “she had lost a considerable amount of her support staff, and that the pharmacy was operating with little help, so she was not terribly surprised that an error could have occurred.”

In an audit, the officers found an error rate of nearly 22 percent, or 66 errors out of 305 prescriptions. Some of the mistakes were minor and would not affect a patient — such as the incorrect name of a prescribing physician — but others were more significant, like instructions for medications that were unclear or substantially different from what they should have been.

Days later, a prescriber complained of insufficient staffing at a pharmacy in Moore, about 10 miles south of Oklahoma City, saying calls were placed on hold for up to 60 minutes. Compliance officers reported finding one pharmacist and one technician who had fallen behind on work.

The officers recorded a 6 percent error rate, according to the complaint. Some of the errors were substantial, including the wrong dose of an antibiotic for a 1-year-old, the incorrect frequency for an antiviral drug (every two hours instead of 12) and multiple errors involving the frequency of a narcotic.

There were several reported errors involving testosterone; in one case, the dose was doubled for a female patient. The compliance officers also noted mistakes related to blood pressure, gastric disorder and steroid medications that had been dispensed to or entered for the wrong patients.

Errors were also flagged in a complaint about a pharmacy in Choctaw, east of Oklahoma City, in February. Inspectors said a computer screen showed more than 99 prescriptions waiting to be filled and more than 99 calls needing to be made.

When asked about the backlog, the pharmacist said that employees were several days to weeks behind, according to the complaint, adding that they had been given an extra 17 hours of technician help but could not find anyone who would work only 17 hours.

Similar staffing concerns were detailed in the case involving the disabled teenager. The pharmacist on duty that day, according to the complaint, was responsible for checking 194 prescriptions in a six-hour shift, about one every two minutes.

The store’s lead pharmacist told the board that he had no control over staffing, and that while he complained about the issue to his district leader, she also had no power to make changes.

That district leader, Amanda Dixon, who is a pharmacist, told The Times in an interview this week that “district leaders were repeatedly voicing their concerns about the budgets” for staffing at CVS pharmacies last year.

Dr. Dixon said that many pharmacies in her 19 stores were short-staffed, that customer complaints were on the rise and that she was worried about patient safety. She had worked for CVS for almost six years until November, when, she said, she was terminated for a policy violation involving another employee, although she believes she may have been retaliated against by the company because of the board’s investigation.

In its statement on Wednesday, Michael DeAngelis, the CVS spokesman, said that “if a pharmacist has a legitimate concern about working conditions, we make every effort to address that concern in good faith.” He added that any suggestion the company retaliated against a district leader was false.

In addition to the fines, the state board said it “strongly recommended” that the company follow through on nearly a dozen recommendations for all of its Oklahoma pharmacies, including increased training for technicians and changes to how staffing needs were determined.

The board also advised eliminating tasks that might overburden pharmacists and removing some metrics they are required to meet. Phone calls pharmacists often must make, it said, could be outsourced to a corporate call center.

Mr. DeAngelis said the company would review the board’s recommendations, noting that CVS had reduced its overall metrics this year and was planning to increase staffing in the fall to help handle vaccines for flu season.