TRENTON, N.J. — For decades, seasonal allergy sufferers had two therapy options to ease the misery of hay fever. They could swallow pills or squirt nasal sprays every day for brief reprieves from the sneezing and itchy eyes. Or they could get allergy shots for years to gradually reduce their immune system’s overreaction.

Now patients can try another type of therapy to train their immune system, new once-a-day tablets that dissolve quickly under the tongue and steadily raise tolerance to grass or ragweed pollen, much like the shots.

“It’s been several decades since the last big breakthrough,” Cleveland Clinic allergy specialist Dr. Rachel Szekely said.

The downside: The pills must be started a few months before the grass or ragweed pollen season. That means it’s too late for people with grass allergies, but the time is now for ragweed allergy sufferers.

The Food and Drug Administration in April approved two tablets from Merck, Grastek for grass pollen and Ragwitek for ragweed, plus a grass pollen tablet called Oralair from Stallergenes.

The tablets could become popular with people who dislike pills that can make them drowsy or don’t provide enough relief. They’ll likely appeal even more to patients with severe allergies who fear needles or can’t make frequent trips to the allergist, key reasons that only about 5 percent of U.S. patients who would benefit from allergy shots get them.

Meanwhile, new treatments for other types of allergies, including to peanuts and eggs, are in various stages of testing and could turn out to be big advances.

Merck has a tablet for house dust mite allergies in final patient testing that could hit the market in two or three years, and it’s considering other therapies.

France’s Stallergenes is testing a tablet for birch tree allergies and, with partner Shionogi & Co. in Japan, tablets for allergies to dust mites and Japanese cedar pollen. Britain’s Circassia Ltd. has a cat allergy treatment in final testing and six others in earlier testing.