States are enacting strict limits on the number of powerful prescription painkillers doctors can prescribe, a move that many believe will help fight the opioid crisis but has raised alarms among some physicians.

At least 17 states have enacted rules to curb the number of painkillers doctors can prescribe. Some, including Arizona, Connecticut, Delaware, Massachusetts, New Jersey and Ohio, have passed laws limiting the duration of initial opioid prescriptions to five or seven days. Others are passing dosage limits. In Kentucky, a law went into effect last month capping opioid prescriptions for acute pain to three days.

“We know that most people who eventually become addicted to heroin have started with a prescription opiate,” said Kentucky state Rep. Kimberly Moser (R), who sponsored the bill and is also a nurse. Kentucky, like most other states, has exemptions for cancer and hospice patients, major surgeries and patients dealing with severe or chronic pain. “We felt it was important to just set that pause button and have prescribers just stop and think about the appropriateness of what they’re prescribing. Is it medically necessary?” she said.

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Last year, 1,404 people died of drug overdoses in Kentucky, according to the Kentucky Office of Drug Control Policy. About half of the deaths involved fentanyl, a powerful synthetic painkiller that is often used in hospitals but also has been manufactured illicitly overseas and has cut into the heroin supply.

The Centers for Disease Control and Prevention last year issued guidance for providers, recommending shorter durations for opioid prescriptions, stating that three days should be sufficient and a course of more than seven days “will rarely be needed.” According to a CDC study, patients who use such painkillers for longer periods of time are more likely to end up addicted to them.

[ Deaths from drug overdoses soared in the first nine months of 2016 ]

Sens. John McCain (R-Ariz.) and Kirsten Gillibrand (D-N.Y.) introduced federal legislation in April to limit an initial opioid prescription to seven days. It would not apply to the treatment of chronic pain, cancer, hospice or palliative care.

More than 52,000 people died of drug overdoses in 2015, according to the CDC. Drug overdoses sharply increased during the first nine months of 2016, according to the National Centers for Health Statistics. They were driven by increases in opioid deaths, especially from heroin and fentanyl. But for many people, their first exposure to opioids is through prescription painkillers.

“Given that this current opioid epidemic is in very real part caused by the prescribers, we should be okay with some guidance,” said R. Corey Waller, chair of the legislative advocacy committee for the American Society of Addiction Medicine. “If we had been able to control this and follow the evidence, we wouldn’t necessarily need these rules.”

But Waller and other physicians also have concerns with the new state laws. In Connecticut, doctors worried that a law limiting initial opioid prescriptions to seven days would be overly prohibitive, said David Emmel, chair of the Connecticut State Medical Society’s legislative committee. But now that the regulations have been in place for about a year, doctors have adapted to the rules, which Emmel said are “not horrifically restrictive.”

Mishael Azam, chief operating officer of the Medical Society of New Jersey, said the state’s five-day limit, which went into effect earlier this year, is still a “work in progress” for the state’s physicians. Doctors, she said, are still being educated about the law and some are now leery of treating pain patients because of it.

“That’s the general tone — doctors are to blame,” she said, and treating a patient individually is discouraged. “Medicine, in all other realms, we’re supposed to be personalizing and individualizing. But when you do a hard mandate, it doesn’t allow for any sort of personalization.”

Patrick Padgett, executive vice president of the Kentucky Medical Association, said some doctors are glad that there is a limit on the number of days a painkiller can be prescribed, because it gives them a guideline they can show to patients who are seeking longer courses of the drug.

Patrice Harris, chair of the American Medical Association board of trustees, said doctors recognize that it is important to cut back on the number of opioids that are prescribed.

“I think there’s been a general agreement that we need to be more judicious in our prescribing,” she said.