They had fevers, aches, runny noses, the normal stuff of childhood. The kind of illnesses for which a doctor would prescribe cough syrup.

But the children’s condition only worsened. They developed persistent diarrhea, then could no longer urinate, as their kidneys failed. The very medicines that were supposed to make them better, simple cough syrups imported from India, were instead killing them, because they turned out to be poison.

In all, 70 children in the tiny West African nation of Gambia are suspected to have died in recent months from contaminated Indian-made cough syrups. Among them was 2-year-old Muhammad Lamin Kijera, who died on Aug. 4.

“He was lively and likable — he was everybody’s friend,” said his father, Alieu Kijera, who works as a nurse at an eye clinic in Banjul, the Gambian capital. “How can they allow something like this into the country, destroying lives?”

India has taken to calling itself “the world’s pharmacy” as its drug industry has expanded rapidly, providing a lifeline to the developing world by selling medicines, many of them generics, for an array of illnesses like malaria and AIDS at prices lower than those of American or European drugs.

But the deaths in Gambia have raised alarm over what one expert called a “dangerous cocktail”: on one side, a $50 billion Indian pharmaceutical industry whose regulation has remained loose and chaotic despite repeated calamities, and on the other, poor nations with little or no way to test the quality of the medicines they import.

India’s drug industry, experts say, is rife with data fraud, inadequate testing and substandard manufacturing practices. While people around the world take Indian medicines every day without incident, the regulatory weaknesses give the country’s drug makers openings to cut corners and increase profits, experts say.

That has created a hazardous reality far more widespread than the occasional tragic cases of mass poisonings, and could shake faith in Indian medicines in the places that need them most.

“What happened in Gambia is happening in other African countries without us even knowing,” said Michel Sidibé, the African Union special envoy for the African Medicines Agency, a new body aimed at harmonizing drug regulation across the continent.

“Most African countries don’t have testing capacities nor well-trained regulatory bodies,” Mr. Sidibé said. “The African market is very fragmented, but because of poor regulations, drugs move from one country to another.”

India is the world’s third-largest drug manufacturer by volume, producing 60 percent of global vaccines and 20 percent of generic medicines. In a sign of the world’s reliance on Indian drugs, the country’s pharmaceutical exports increased nearly 20 percent during the first year of the pandemic, reaching $24 billion, despite lockdowns that disrupted global supply chains.

As a stamp of approval for the quality of Indian medicines, officials point out that more than half of the drugs manufactured in India go to highly regulated markets — “every third pill in the U.S. and every fourth pill in Europe is sold from India,” according to the Indian Pharmaceutical Alliance.

It is the other half where the danger may lie.

Dinesh Thakur, a public health activist and industry whistle blower who pulled the curtain on some of its perilous practices, and Prashant Reddy, a lawyer and researcher, chronicled India’s regulatory gaps in a recent book, “The Truth Pill.”

Mr. Thakur, Mr. Reddy and other experts have long suspected that Indian manufacturers may be taking shortcuts with some medicines bound for export to markets with poorer quality controls. Some of the evidence is anecdotal, but they point to a limited study in which the quality of Indian drugs was tested across multiple importing nations, as well as Indian drug products that have drawn complaints and blacklisting in other countries.

They also note that regulatory bodies of Western nations, such as the Food and Drug Administration in the United States, carry out regular inspections of Indian factories that manufacture drugs for their markets. But poorer nations do not have the resources to do the same, leaving the products shipped to their countries at the mercy of loose Indian regulation.

“Drugs they export to Africa tend to be of lower quality than the other markets,” Mr. Reddy said, “because they know they are more likely to get away with substandard drugs.”

The problem with cough syrups is an old one, so old that similar contamination issues helped lead to the United States’ strict drug regulations and the creation of the F.D.A. nearly a century ago.

In recent decades, several cases of mass deaths from drugs made in China, a big producer of medicines and pharmaceutical raw materials, have been traced to cough syrups. In those cases, counterfeiters were found to have used diethylene glycol and ethylene glycol, which break down into toxic compounds in the body, instead of more expensive nontoxic solvents.

In India, at least five mass-death episodes caused by diethylene glycol contamination have been recorded since the 1970s. The Indian-made syrups exported to Gambia were also found to have high amounts of diethylene glycol and ethylene glycol. But they were produced by a licensed manufacturer, not counterfeiters, as in China.

India has an antiquated model of regulation that focuses on checking the end product. The F.D.A., by contrast, has a “process-oriented” regulatory framework, which focuses on quality and safety checks during the manufacturing of a drug.

The process falls short in India, Mr. Thakur and Mr. Reddy said, because of a lack of resources in conducting the product checks, as well as widespread corruption.

Manufacturers take advantage of loopholes in a layered system of regulation in India’s federal system. The central government is charged with ensuring the quality of imported drugs and approves new drugs. But state governments are largely responsible for enforcing drug regulations, both for domestic use as well as manufacturing for export.

Mr. Thakur said that state governments often had budgets much too small to continuously purchase drugs from the markets for testing. Even when a drug in one state is found to be hazardous, jurisdiction issues and weak legal frameworks prevent swift recalls.

“For the state governments, state capacity is very low, and drug regulation is an extremely low priority for them,” Mr. Reddy said.

Only recently have there been efforts in India to create a consolidated central database where test results from one state can be easily shared with others. Partial data uploaded from three states alone showed about 7,500 failures — because of problems like insufficient active ingredients, difficulties with metabolism or bacterial contamination — of drugs on the market that those states had tested over the past decade.

The four syrups linked to the deaths in Gambia were produced by Maiden Pharmaceuticals. The three-decade-old firm manufactures drugs in the state of Haryana. Maiden’s website, which says one of the company’s principles is “at any cost don’t compromise on quality,” shows that its exports reach four dozen countries.

Maiden, in a statement, said that it had “valid drug approvals for the export of the products in question” and that the raw material for the drugs had come from “certified and reputable companies.”

But Maiden had been flagged before for substandard products. The database shows that in the state of Kerala, five of its products failed tests in 2021. Eight years earlier, the consul general of India in Ho Chi Minh City named Maiden among 46 Indian companies that Vietnamese drug controllers had “blacklisted for quality violation,” asking for action against them “for bringing bad name to the Indian pharma industries abroad.”

In the Gambia case, the country’s Medicines Control Agency, working with the W.H.O., alerted the Indian government to the problems with the syrups on Sept. 29 and ordered a recall on Oct. 4, nearly three months after the doctors in the Banjul hospital had begun seeing a pattern.

A day later, the W.H.O., which had sent samples to Switzerland and Senegal for testing, announced that lab tests had confirmed the presence of “unacceptable amounts” of diethylene glycol and ethylene glycol in the syrups.

Hundreds of Red Cross volunteers raced to intercept the contaminated syrups in Gambia, one household and pharmacy at a time. Out of 50,000 bottles of contaminated syrup, the Gambian police said that 41,500 had been recalled, but that the rest remained unaccounted for.

Many children who took the syrups are still fighting for their lives, as doctors in Gambia had continued prescribing them as late as mid-September.

The alarm has spread beyond Gambia. While the syrups are not registered for sale in most other West African countries, once a product is in the region, “it’s very difficult to control its circulation due to porous borders,” said Arnaud Pourredon, the founder of Meditect, an Ivory Coast-based company that helps pharmacists digitize their stocks and track fake medicines.

In India, officials raided the production site in Haryana two days after they were alerted by the Gambian government. On Oct. 11, they ordered Maiden’s production facility to close.

Haryana and national regulatory bodies said in a joint statement that “the firm has been manufacturing and testing drugs without adhering to and in contravention” of accepted manufacturing practices and that Maiden “has not maintained and not produced complete records of manufacturing and testing as per rules.”

But the central government tried to shift responsibility, saying the burden for ensuring quality rested on Gambia as the importing country.

Gambia’s health minister acknowledged that the country did not have labs to test imported medicines. The nation’s pharmaceutical regulatory body, established in 2014, relies on certificates provided by manufacturers, said Salieu Taal, a lawyer and the president of the Gambia Bar Association.

He said that the loose regulations in some exporting countries and the lack of resources for testing in recipient nations had left many African countries facing “a very dangerous cocktail.”

“There may be more deaths than we have recorded,” Mr. Taal said.

Mady Camara contributed reporting from Dakar.