A controversial drug that has been given to thousands of Canadian soldiers and is still in use in the military was deemed too risky for British troops in a landmark report released Tuesday.

The report by MPs on the U.K. parliamentary defence committee recommended that the British military use the anti-malaria drug mefloquine only as a “drug of last resort,” due to the risk of severe psychological side effects.

While adverse reactions to the drug are “in the minority, we do not believe that the risk and severity of these side effects are acceptable for our military personnel overseas,” the report said.

In Canada, the report was welcomed by veterans who say the Canadian military has lagged behind its allies in restricting the drug’s use and addressing the legacy of long-term side effects among soldiers.

“Canada should get in lockstep with its allies on this issue” said former Canadian Airborne Regiment soldier John Dowe, head of a three-country advocacy group pushing for an end to the military use of mefloquine.

Mefloquine, also sold under the brand name Lariam, is one of several drugs used by the Canadian military to prevent malaria on missions to countries where the disease is present.

According to pharmacy records, 15,677 Canadian soldiers were given the drug between January 2001 and March 2012, said National Defence spokeswoman Jennifer Eckersley.

The U.S. army restricted the drug in July 2013 when the U.S. Food and Drug Administration issued a so-called “black-box” warning — its strongest warning label — that highlighted possible permanent side effects such dizziness, insomnia and seizures, as well as psychiatric reactions such as paranoia, depression and anxiety.

“Neurological side effects can occur any time during drug use and can last for months to years after the drug has stopped and can be permanent,” the warning reads.

Drug manufacturer Roche requires an individual risk assessment before prescribing the drug — a step the U.K. report says was often omitted during large-scale deployments of soldiers.

Mefloquine is now used much less frequently, Eckersley said, noting that the drug was given to the majority of soldiers who took an anti-malarial in 2002-03, but just 6 per cent received it in 2012.

“We are aware of the latest U.K. Report and will be reviewing it light of Canadian armed forces’ use of the drug,” she said.

The drug was first issued to Canadians in the ill-fated 1992-93 Somalia mission. All 900 soldiers with the Canadian Airborne Regiment on that mission were given the drug as part of a clinical trial. Mefloquine was unlicensed in Canada at the time, and some veterans of the mission have blamed the drug’s side effects for violence by some soldiers, including the beating death of a Somali teen.

Dave Bona, a former Canadian Airborne soldier who suffered serious side effects from mefloquine in Somalia and Rwanda, said the U.K. report should be a turning point in Canada.

“After this report, it should be clear to the federal government. If they don’t take action, there is something seriously wrong,” said Bona from his home near Saskatoon.

After taking his first dose, Bona felt nauseous and had seizures that night. He was plagued by insomnia, nightmares and “explosive anger” during his nine-month deployment.

Bona experienced the same pattern after taking the drug in Rwanda in 1994. “I’d get so angry I could not think straight,” he said.

After his deployments, Bona’s symptoms followed him back to Canada. His marriage broke up, he turned to alcohol and he had trouble keeping jobs.

In 1999, an Auditor General’s report found that the defence department improperly prescribed mefloquine on the Somalia deployment and failed to track soldiers’ side effects as required by the clinical trial.

In 2000, Bona was kicked out of the army over his problems with alcohol. He was later diagnosed with PTSD.

For 12 years, Bona said he took every treatment possible for PTSD, but he got little relief until his long-time psychologist told him his symptoms matched mefloquine toxicity.

“I’ve done everything they said to do and still I got no relief. But it’s like breaking a leg and getting treatment for a broken arm.”

If the U.K. defence department accepts Tuesday’s recommendations, Britain will join the Australian and U.S. militaries in restricting the drug.

Canadian soldiers currently take mefloquine at five times the rate of Americans, said Dr. Remington Nevin, a former U.S. military physician and the leading expert in the neuropsychiatric effects of the drug.

Nevin, who gave evidence at the U.K. inquiry in December, said less than 1 per cent of U.S. soldiers take mefloquine under the tighter restrictions there.

“Canada is now increasingly isolated in not taking action,” said Nevin.

“It is uncharacteristic of Canada to be so far behind on such a major health issue,” he added.

Mefloquine’s side effects are especially difficult to monitor in a battle situation, as soldiers tend to “under report” symptoms or may attribute some side effects such as insomnia to other factors, the U.K. report noted.

“All of our witnesses acknowledged that there is a risk that some military personnel may hide symptoms in the belief that doing otherwise could jeopardize their careers,” the report said.

During the inquiry, the U.K. minister for welfare and veterans apologized to British soldiers who were given the drug improperly.

Bona and other veterans of the now-disbanded Canadian Airborne Regiment say they want a similar apology.