Appetite suppressants are not new. Often, they're also not safe. Many drugs that curb our tendency to eat too much have shown they're not good for our heart.

That, however, might all be about to change. This week, scientists are reporting what they say is the first clinical evidence of a drug successfully bringing about weight loss without putting the heart and cardiovascular system at risk.

"The study showed for the first time in a rigorous, randomised way that this weight loss drug helps people lose weight without causing an increase in adverse cardiovascular events in a population at higher risk for heart attacks and strokes," explains cardiologist Erin Bohula from Brigham and Women's Hospital in Boston, Massachusetts.

Bohula is talking about lorcaserin – sold in the US under the brand name Belviq – which suppresses appetite by activating a serotonin receptor in the brain that promotes sensations of satiety.

While Belviq was approved as a weight loss drug by the FDA back in 2012, data on its long-term safety was non-existent, which – in light of the kinds of health risks other anorectics have demonstrated – was a problem.

"Patients and their doctors have been nervous about using drugs to treat obesity, and for good reason," Bohula told AP.

"There's a history of these drugs having serious complications."

To ascertain if lorcaserin posed the same kind of problems as its predecessors, Bohula and her team ran a multi-year clinical trial in which 12,000 overweight or obese patients with a median age of 64 were randomly administered a twice-daily dose of the drug, or a placebo.

At the end of the trial – in which participants were monitored for a median period of 3.3 years – those who took the lorcaserin in addition to undergoing lifestyle interventions lost an average of 4 kilograms (9 lbs) on average, almost double the loss realised by those taking the placebo.

But we already knew lorcaserin, like other suppressants before it, successfully promoted (modest) weight loss – the more important finding here was that the drug did this sustainably, while not raising risk of cardiovascular events.

Over the duration of the study, 6.1 percent of the group taking lorcaserin experienced a major adverse cardiovascular event – effectively the same amount of people (6.2 percent) from the placebo group.

While nobody is suggesting lifestyle change shouldn't be the primary emphasis for most overweight and obese patients, a safe weight-loss drug like this could provide a much-needed third option in between diet/exercise adjustments and invasive surgical interventions such as bariatric tummy tucks.

"I think it is the thing everybody has been looking for," the chair of Britain's National Obesity Forum, Tam Fry, who wasn't involved with the research, told the Press Association.

"I think there will be several holy grails, but this is a holy grail and one which has been certainly at the back of the mind of a lot of specialists for a long time."

It's worth bearing in mind that some participants taking the drug during the trial experienced adverse side effects, including dizziness, fatigue, headache, nausea, and diarrhoea.

Some are arguing we still need additional long-term studies to confirm these results after the 40-month period of the study, and that's a fair point to consider.

But for many overweight and obese patients, the medication – which costs between US$220 to $290 monthly in the US – could finally offer a drug that helps them lose weight safely, without putting their hearts at risk.

"We're so scared of the old drugs and valve damage," cardiologist Stephan Achenbachhe from the University of Erlangen in Germany, who wasn't involved with the research, told TCTMD.

"That's what we all have in our minds… So this is a relief. This is a drug that is safe."

The findings are reported in The New England Journal of Medicine.