I've never had an issue with carrying gels but I've been given some dodgy looks and make sure that it has the size on the packet. One gel I got from decathlon didn't have this and they threw it away.
As Wilkie said - make sure that you don't exceed 1 litre and I'd recommend using the right size bag as I've been told off once or twice for that.
I normally split out toiletries amongst the people I'm travelling with if its too much (e.g. Shower gel/gels etc)