Online gambling, stretching from poker to sports betting, has exploded worldwide in recent years and in Europe in particular.
European Union data shows that in 2012, seven million Europeans gambled online, making up a huge 45-percent share of the world market, which according to industry data, was worth $33 billion (24 billion euros) that year.
The explosion in European online gambling began in a smaller group of member states, including Britain and Malta, where companies flourished, drawing in gamblers from around the world.
Other member states -- such as France and the Netherlands -- for many years delayed growth, keen to not only protect consumers but lucrative state gambling monopolies as well.
Under pressure from Brussels, these countries have now opened up their markets, although at varying levels.
"We must better protect all citizens, and in particular our children, from the risks associated with gambling," said the EU's internal market and services commissioner, Michel Barnier.
"We now look to the member states, but also to online gambling operators, to match our ambition for a high level of consumer protection throughout the EU in this fast growing digital sector," he said.
The main elements of the recommendations include clearer warnings on websites, more rigorous registration procedures to ward off minors, and a ready access to helplines for gambling addicts.
Advertising should also be regulated, the EU said, and free of "unfounded statements about chances of winning" or of pressure to gamble.
The European gambling industry, eager for less fragmentation, welcomed the recommendations, which are non-binding.
"European consumers deserve to be equally well protected throughout the EU, wherever they reside," said Maarten Haijer, head of the European Gaming and Betting Association.
An EU-wide policy for online gambling "is evidently necessary for this cross-border internet sector," he added.
Gambling is a hot-button issue in many member states, seen as both a source of state revenue and the potential cause of harm.
The Commission said it chose to draft recommendations, instead of outright legislation, as the latter takes too long and risks failure.
With several member states in the process of devising national legislation, the EU recommendations can be used a guidance, the Commission said.