Lee Higman, a 71-year-old artist from Bellevue, Idaho, who considers herself a law-abiding citizen, was shocked last month when she got a notice from the Food and Drug Administration telling her: “A mail shipment addressed to you from a foreign country is being held.”

The 90 tablets of Vagifem, prescribed by her physician, that she had ordered from a Canadian pharmacy had been impounded as an illegal drug at Los Angeles International Airport.

First marketed in 1988, Vagifem estrogen tablets are used by millions of women to relieve symptoms of menopause. There is no generic version available in the United States, and brand-name drugs are expensive here. So about five years ago, Mrs. Higman started ordering the tablets from Canada, where a year’s supply that would cost about $1,000 in the United States sells for under $100.

“The price went up. And we’d lost a lot on the stock market, and we’re living on fixed incomes,” Mrs. Higman, who is an artist, said in an interview. She and her husband, a writer, are covered by Medicare. In an e-mail to the Food and Drug Administration, she sought the release of the package, explaining, “When it became economically imperative I ordered it from Canada, a country with strict drug requirements.”

The high price of many prescription drugs in the United States has left millions of Americans telling white lies and committing fraud and other crimes to get their medicines. In response to a New York Times article about the costs, hundreds of readers shared their strategies, like having a physician prescribe twice the needed dose and cutting pills in half, or “borrowing” medicines from a friend or relative with better insurance coverage. But an increasingly popular — though generally illegal — route is buying the drugs from overseas.

The Canadian International Pharmacy Association, a 10-year-old group, said its members fill prescriptions for one million Americans each year. “It’s the Americans who are seeking us out,” said Tim Smith, the group’s general manager. “Clearly there’s a need.”

In surveys from 2011 by the Centers for Disease Control and Prevention, about 2 percent of adults and about 5 percent of the uninsured said they had bought prescription drugs from other countries. The figures most likely underestimated the practice because people may be reluctant to admit to doing something illegal, even though the law is rarely enforced in such cases.

The Food and Drug Administration says on its Web site that “in most circumstances it is illegal to import drugs into the U.S. for personal use” because the agency cannot guarantee they are safe and effective. The government also prohibits “reimportation” of drugs made in the United States because it cannot guarantee the medications were not tampered with or stored improperly.

The agency said it does not track the volume of such imports. However, it “typically does not object” to people buying imported medicine for personal use “under certain circumstances,” the agency said. Those include using the drug to treat a serious condition for which an effective alternative is unavailable in the United States and purchasing less than a three-month supply. But those ambiguous edicts have left patients wary.

Dr. Stephen Barrett, a retired psychiatrist and health care advocate in North Carolina, said he has saved thousands of dollars buying medicines from overseas in the past decade. “It may be technically illegal, but I don’t think anyone would ever get prosecuted,” he said, adding that such laws reflected “protectionism” for drug makers. Although the Obama administration initially proposed allowing some importation of drugs, the idea was dropped from the Affordable Care Act after intense opposition from the pharmaceutical industry.

Mr. Smith, of the Canadian pharmacy group, said members follow strict pharmacy and prescription protocols and dispense only medicines approved by Health Canada, which regulates them. Members also broker purchases from licensed pharmacies in other countries, like Britain and Australia, which may further reduce the costs. Package inserts in foreign languages must be translated into English.

He acknowledged that consumers must take care to ensure an online pharmacy is legitimate, noting that in 2011 his association sent hundreds of cease-and-desist letters to Web sites — some of which were not based in Canada and were not even pharmacies — that were fraudulently using the group’s certification seal.

Dr. Barrett said he uses Web sites like PharmacyChecker.com to screen online pharmacies and prefers products from English-speaking countries.

Some purchases from overseas pharmacies are identical to products sold in the United States. When a Food and Drug Administration compliance officer told Mrs. Higman that her order of Vagifem was held because it was an “unapproved” drug, she responded, “This drug might come from Turkey, however, it is in the same box, the same packaging, the same labels, the same manufacturer, Nordisk, as the outrageously priced Vagifem in the United States.”

Identical drugs sold in other countries may have different package inserts, slight variations in dose or different brand names. But that is frequently a function of patent law and business decisions by drug makers, rather than medical efficacy.

Diana Simonson, 42, a freelance computer programmer in Glens Falls, N.Y., said she started ordering her inhalers from Canada after she nearly died of an asthma attack in the United States, where she cannot afford her preventive treatments.

For decades, she was able to control her asthma with a steroid inhaler. But it was banned a few years ago because it contained a propellant that was deemed environmentally harmful. The replacement product cost $250 a month. “That was like another car payment — I couldn’t do it,” said Ms. Simonson, who has a high-deductible insurance policy through the Freelancers Union.

With an income of about $35,000 and a child to raise, she tried to do without. But at an air show with her 7-year-old son, she became so short of breath that she had to be rushed by ambulance to an emergency room.

The inhalers she gets from Canada every three months are the same brand, and by the same manufacturer, that she used to buy in the United States. But often they are produced in a third country, like Turkey or Malaysia.

Kristen Bailey of Colorado started ordering medicine by mail from India when she was given a diagnosis of Crohn’s disease after graduating from college in 2011 with no insurance. Her medicine retails for tens of thousands of dollars in the United States.

The process is simpler for patients who live near the border. Joshua Kalish, 70, of Silver City, N.M., said that before he was eligible for Medicare, he drove to Mexico to fill his prescriptions, calling it a “common practice.”

Mrs. Higman said she is also heading for the border. Despite her pleas, the Food and Drug Administration told her that her Vagifem tablets would be returned to Canada or destroyed.

To tide her over, she has spent $233 for two months of Vagifem at a local pharmacy. “Fortunately my children and grandchildren live in Seattle, so the next time we go over there, I’ll take a little trip up to Vancouver, British Columbia, to buy my medicine,” she said. “I’ll save enough money to get room service in a five-star hotel there and still have enough left to claim I saved a couple of bucks.”