Doctors have called for an urgent international effort to combat a “pandemic of bad drugs” that is thought to kill hundreds of thousands of people globally every year.

A surge in counterfeit and poor quality medicines means that 250,000 children a year are thought to die after receiving shoddy or outright fake drugs intended to treat malaria and pneumonia alone, the doctors warned.

More are thought to die from poor or counterfeit vaccines and antibiotics used to treat or prevent acute infections and diseases such as hepatitis, yellow fever and meningitis.

Most of the deaths are in countries where a high demand for drugs combines with poor surveillance, quality control and regulations to make it easy for criminal gangs and cartels to infiltrate the market. Often they face only fines or minor sentences if caught.

“The penalties are a slap on the hand, but we are talking about murder by fake medicine here,” said Joel Breman, a senior scientist emeritus at the US National Institutes of Health in Maryland.

Tests on drugs in the field have identified fake and ineffective copies of a vast range of drugs including antimalarials, antibiotics and cardiovascular and cancer medicines. Many fakes originate in China and India and have been found to contain everything from printer ink and paint to arsenic. Lifestyle drugs, such as Viagra, dominate the market for counterfeit medicines.

Beyond the fakes that are made and sold by criminal gangs are poor-quality medicines that lack sufficient active ingredients to work properly, or fail to dissolve correctly when taken. Sloppy manufacturing is often to blame, but others are sold past their shelf life or have degraded in poor storage conditions.

Writing in the American Journal of Tropical Medicine and Hygiene, doctors from the US government, universities, hospitals and the pharmaceutical firm Pfizer warn that the rise in “falsified and substandard medicines” has become a “public health emergency”. On top of the direct harm they cause, bad drugs are a major driver of antimicrobial resistance, which fuels the rise of superbugs. “This is an urgent public health issue and we need to take action,” Breman said.

Up to 10% of drugs in low and middle income countries are poor quality or outright fakes, costing local economies between $10bn and $200bn a year, the report states, and the problem is getting worse. In 2018, Pfizer identified 95 fake products in 113 countries, up from 29 fakes in 75 countries in 2008.

In a raft of recommendations, the doctors call for greater support for the World Health Organization’s (WHO) drug surveillance programme and an update to the UN’s sustainable development goals in which governments would ensure at least 90% of the medicines in their countries were of high quality. Registers of fake drugs found in the field should also be made open to the public, the doctors say.

Another recommendation is for a global treaty on drug quality that builds in the means to gather evidence on fake drug activities, and sets out extradition agreements so that suspects can face trial in countries they target. Such a treaty would encompass illegal online pharmacies, which doctors say are an increasing part of the problem.

Breman said the international community and pharmaceutical companies had to improve the security of the drug supply chain in all countries from the point of manufacture to the patient. There was an immediate need for simple and rapid tests that doctors could use to verify drug quality, he added.

“Very little has been done about this and that’s why our recommendations hit specific things that frankly have been evaded by the powers that be,” Breman said.

Last month, WHO issued a global alert about a fake cancer drug in Europe and the Americas. The counterfeit drug is packaged to look like Iclusig, an anticancer medicine used to treat adults with chronic myeloid leukaemia and acute lymphoblastic leukaemia. WHO said the pill contained nothing but paracetamol.

Michael Deats, who leads the vigilance group on fake medicines at WHO in Geneva, said “the highest political will is required” to ensure that global policies on bad drugs make a difference on the ground. More than 110 countries have reported more than 2,000 cases of bad drugs overWHO’s global surveillance and monitoring system, he added, with new cases arriving every day.

Bernard Naughton, a researcher in falsified and counterfeit medicines at Oxford University’s Saïd Business School, said fake medicine was a “wicked problem” that called for a combined effort from pharma companies, academia, governments, healthcare practitioners and the public.

“The UK legitimate pharmaceutical supply chain is safe but it requires constant monitoring,” he said. “Regarding online pharmacies, there is poor public understanding of how to differentiate between a legitimate online pharmacy and an illegal one. Illegal online pharmacies and the sale of medicines via social media platforms pose the greatest risk to the UK public.”