Sugar-free alternatives, such as Splenda and Stevia, have become more popular amid growing concerns about eating healthily.
However, there is 'no evidence' of the health benefits of the sweeteners when compared to sugar, according to researchers.
A review of 56 studies on sweeteners found no significant differences in people's weight, blood sugar or oral health when compared with people who eat sugar.
But experts have called the findings 'not surprising' and said sweeteners were still a healthier choice than sugar.
The research, published in the British Medical Journal, compared the health of people who used non-sugar sweeteners with those who didn't.
It found slightly lower levels of weight gain, lower body mass indexes (BMIs) and blood sugar levels among sweetener users, but said the evidence was weak.
'No evidence was seen for health benefits from non-sugar sweeteners and potential harms could not be excluded,' said lead researcher Dr Joerg Meerpohl.
'For most outcomes, there seemed to be no statistically or clinically relevant difference between intake versus no intake, or between different doses of non-sugar sweeteners.'
The sweetener aspartame has been linked to cancer and liver damage in the past but research is thin on the ground and it has been declared safe to eat by the EU.
Other sweeteners including saccharin and sucralose have had similar concerns raised and researchers in this new study say harmful effects could not be ruled out.
The research, done by scientists from across Europe and led by Dr Meerpohl, from Germany's University of Frieburg, is the most comprehensive of its kind.
As well as weight and oral health it also considered people's risk of cancer, heart disease, kidney disease and effects on their mood and behaviour.
But experts haven't been moved by the findings.
King's College London's Professor Tom Sanders said: 'The findings of this study are not surprising and confirm the view that artificial sweeteners are not a magic bullet to prevent obesity.
'Replacement of sugary drinks with artificial sweeteners helps prevent weight gain in children but is not superior to the preferred alternative – water.'
And Professor Naveed Sattar of the University of Glasgow, added: 'This paper does not change my mind.
'Non-sugar sweeteners remain far better than sugar sweetened beverages given lack of calories in the former, and the well-known harms of the latter including in particular on dental health.'
The scientists admitted the evidence in many of the studies was low quality so more in-depth long-term research is needed.
In a BMJ editorial alongside the study, Harvard University's Vasanti Malik maintained sweeteners could be healthier than sugar when it comes to soft drinks.
She said: 'Based on existing evidence, use of non-sugar sweeteners as a replacement for free sugars, particularly in sugar sweetened drinks, could be a helpful strategy to reduce cardiometabolic risk [chances of having diabetes, heart disease or stroke] among heavy consumers, with the ultimate goal of switching to water or other healthy drinks.
'Policies and recommendations will need updating regularly, as more evidence emerges to ensure that the best available data is used to inform the important public health debate on sugar and its alternatives.'
The research comes as public health officials in the UK have warned they will call for more taxes on sugary foods if companies don't reduce amounts in their food.
The chief nutritionist at Public Health England, Dr Alison Tedstone, this week called for a 'pudding tax' to force companies to cut sugar levels or make customers pay.
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