The phone awakened Doug Nordman at 3 a.m. A surgeon was calling from a hospital in Grand Junction, Colo., where Mr. Nordman’s father had arrived at the emergency room, incoherent and in pain, and then lost consciousness.

At first, the staff had thought he was suffering a heart attack, but a CT scan found that part of his small intestine had been perforated. A surgical team repaired the hole, saving his life, but the surgeon had some questions.

“Was your father an alcoholic?” he asked. The doctors had found Dean Nordman malnourished, his peritoneal cavity “awash with alcohol.”

The younger Mr. Nordman, a military personal finance author living in Oahu, Hawaii, explained that his 77-year-old dad had long been a classic social drinker: a Scotch and water with his wife before dinner, which got topped off during dinner, then another after dinner, and perhaps a nightcap.

Having three to four drinks daily exceeds current dietary guidelines, which define moderate consumption as two drinks a day for men and one for women, or less. But “that was the normal drinking culture of the time,” said Doug Nordman, now 63.

At the time of his 2011 hospitalization, though, Dean Nordman, a retired electrical engineer, was widowed, living alone and developing symptoms of dementia. He got lost while driving, struggled with household chores and complained of a “slipping memory.”

He had waved off his two sons’ offers of help, saying he was fine. During that hospitalization, however, Doug Nordman found hardly any food in his father’s apartment. Worse, reviewing his father’s credit card statements, “I saw recurring charges from the Liquor Barn and realized he was drinking a pint of Scotch a day,” he said.

Public health officials are increasingly alarmed by older Americans’ drinking. The annual number of alcohol-related deaths from 2020 through 2021 exceeded 178,000, according to recently released data from the Centers for Disease Control and Prevention: more deaths than from all drug overdoses combined.

An analysis by the National Institute on Alcohol Abuse and Alcoholism shows that people over 65 accounted for 38 percent of that total. From 1999 to 2020, the 237 percent increase in alcohol-related deaths among those over age 55 was higher than for any age group except 25- to 34-year-olds.

Americans largely fail to recognize the hazards of alcohol, said George Koob, the director of the institute. “Alcohol is a social lubricant when used within the guidelines, but I don’t think they realize that as the dose increases it becomes a toxin,” he said. “And the older population is even less likely to recognize that.”

The growing number of older people accounts for much of the increase in deaths, Dr. Koob said. An aging population foreshadows a continuing surge that has health care providers and elder advocates worried, even if older people’s drinking behavior doesn’t change.

But it has been changing. The proportions of people over 65 who report using alcohol in the past year (about 56 percent) and the past month (about 43 percent) are lower than for all other groups of adults. But older drinkers are markedly more likely to do it frequently, on 20 or more days a month, than younger ones.

Moreover, a 2018 meta-analysis found that binge drinking (defined as four or more drinks on a single occasion for women, five or more for men) had climbed nearly 40 percent among older Americans over the past 10 to 15 years.

What’s going on here?

The pandemic has clearly played a role. The C.D.C. reported that deaths attributable directly to alcohol use, emergency room visits associated with alcohol, and alcohol sales per capita all rose from 2019 to 2020, as Covid arrived and restrictions took hold.

“A lot of stressors impacted us: the isolation, the worries about getting sick,” Dr. Koob said. “They point to people drinking more to cope with that stress.”

Researchers also cite a cohort effect. Compared to those before and after them, “the boomers are a substance-using generation,” said Keith Humphreys, a psychologist and addiction researcher at Stanford. And they’re not abandoning their youthful behavior, he said.

Studies show a narrowing gender divide, too. “Women have been the drivers of change in this age group,” Dr. Humphreys said.

From 1997 to 2014, drinking rose an average of 0.7 percent a year for men over 60, while their binge drinking remained stable. Among older women, drinking climbed by 1.6 percent annually, with binge drinking up 3.7 percent.

“Contrary to stereotypes, upper-middle-class, educated people have higher rates of drinking,” Dr. Humphreys explained. In recent decades, as women grew more educated, they entered workplaces where drinking was normative; they also had more disposable income. “The women retiring now are more likely to drink than their mothers and grandmothers,” he said.

Yet alcohol use packs a greater wallop for older people, especially for women, who become intoxicated more quickly than men because they’re smaller and have fewer of the gut enzymes that metabolize alcohol.

Seniors may argue that they are merely drinking the way they always have, but “equivalent amounts of alcohol have much more disastrous consequences for older adults,” whose bodies cannot process it as quickly, said Dr. David Oslin, a psychiatrist at the University of Pennsylvania and the Veterans Affairs Medical Center in Philadelphia.

“It causes slower thinking, slower reaction time and less cognitive capacity when you’re older,” he said, ticking off the risks.

Long associated with liver diseases, alcohol also “exacerbates cardiovascular disease, renal disease and, if you’ve been drinking for many years, there’s an increase in certain kinds of cancers,” he said. Drinking contributes to falls, a major cause of injury as people age, and disrupts sleep.

Older adults also take a lot of prescription drugs, and alcohol interacts with a long list of them. These interactions can be particularly common with pain medications and sleep aids like benzodiazepines, sometimes causing over-sedation. In other cases, alcohol can reduce a drug’s effectiveness.

Dr. Oslin cautions that, while many prescription bottles carry labels that warn against using those drugs with alcohol, patients may shrug that off, explaining that they take their pills in the morning and don’t drink until evening.

“Those medications are in your system all day long, so when you drink, there’s still that interaction,” he tells them.

One proposal for combating alcohol misuse among older people is to raise the federal tax on alcohol, for the first time in decades. “Alcohol consumption is price-sensitive, and it’s pretty cheap right now relative to income,” Dr. Humphreys said.

Resisting industry lobbying and making alcohol more expensive, the way higher taxes have made cigarettes more expensive, could reduce use.

So could eliminating barriers to treatment. Treatments for excessive alcohol use, including psychotherapy and medications, are no less effective for older patients, Dr. Oslin said. In fact, “age is actually the best predictor of a positive response,” he said, adding that “treatment doesn’t necessarily mean you have to become abstinent. We work with people to moderate their drinking.”

But the 2008 federal law requiring health insurers to provide parity — meaning the same coverage for mental health, including substance use disorders, as for other medical conditions — doesn’t apply to Medicare. Several policy and advocacy groups are working to eliminate such disparities.

Dean Nordman never sought treatment for his drinking, but after his emergency surgery, his sons moved him into a nursing home, where antidepressants and a lack of access to alcohol improved his mood and his sociability. He died in the facility’s memory care unit in 2017.

Doug, whom his father had introduced to beer at 13, had been a heavy drinker himself, he said, “to the point of blackout” as a college student, and a social drinker thereafter.

But as he watched his father decline, “I realized this was ridiculous,” he recalled. Alcohol can exacerbate the progression of cognitive decline, and he had a family history.

He has remained sober since that pre-dawn phone call 13 years ago.