However, the airline declined to comment on whether the situation would hurt its full-year profit guidance. Ryanair expects net profit over the year to be up 5 percent to 10 percent on the euro301.5 million it made last year.
Learmount said budget airlines might be able to make some money going forward from increased sales onboard if restrictions remained on purchases of duty-free goods before boarding.
Bryon, however, said that any new restrictions on sales of goods like bottles of alcohol would likely apply to onboard sales as well as at gate-side shops, restricting the abilities of low-cost airlines to spread the extra costs - unlike full-cost airlines that can leverage the cost over a wider base.
"I don't think we will be able to go back to those days of relaxed onboard baggage, which means things will have to change," he said.
There are fears that no-frills airlines won't be able to avoid passing on to their customers the costs of tougher long-term security measures.
As the immediate security threat at British airports wanes, airlines are beginning to count the multimillion dollar cost of the terrorist alert - and consider who should pay.
Ryanair has a network of more than 360 routes serving 23 countries across Europe.
Budget airline Ryanair threatened to take legal action unless the British government meets three demands within the next seven days.