An edible allergy vaccine could one day replace injections, a study says.
One in three adults has some form of allergy
Jabs, which build up antibodies are used to treat severe forms of hay-fever and cat and venom allergies, but can sometimes trigger dangerous reactions.
The Japanese researchers said the rice-based vaccine they tested on mice is less dangerous and more simple.
They wrote in the journal Proceedings Of The National Academy of Sciences that it "opens new possibilities" for allergy treatment in the future.
One in four people are estimated to suffer from allergies, ranging from reactions to food to respiratory and skin allergies.
Most can be controlled by regulating diet and the immediate environment - or drugs can be taken to limit the symptoms.
But for severe hay-fever and cat allergies, as well as for people with particularly bad reactions to bee and wasp stings, courses of anti-allergy injections can be given.
These can take a couple of years to complete and have to be done in hospital because of the danger of the allergens given in the jabs prompting an anaphylactic reaction - injections all but stopped for a while in the UK in the 1980s because of a number of deaths.
The vaccine developed by the joint University of Tokyo and Shimane University team uses genetically-modified rice to build up the immune system.
The oral vaccine contains only part of the allergen in comparison to traditional injections and therefore carry less risk of a bad reaction, the study said.
In the tests on mice allergic to cedar pollen, those taking the rice vaccine for four weeks showed fewer allergic responses and sneezed less.
Report co-author Hidenori Takagi said the findings "open new possibilities" for the treatment of allergies.
And he added: "Plant-based vaccines have several potential advantages over traditional whole-allergen injected vaccines since they are simpler to administer and cheaper to produce."
But he said more research was needed before a human vaccine could be produced.
Muriel Simmons, chief executive of Allergy UK, said more research was needed into treating allergies.
"Courses of injections have to be tightly monitored in hospital so anything that offers the hope of an easier and safer way to give them is to be welcomed."