It's that time of year. The sounds of sneezing, coughing, and sniffling can be heard across America. Around 40 million people in the U.S. have seasonal allergies (including hay fever).

Many take popular over-the-counter medications to fight off their allergy symptoms, but more help could be on the way. Several companies have drugs in development that show potential in alleviating the irritating effects of allergies. Here are three promising treatments for this surprisingly common health problem.

Mowing down grass pollens
A frequent trigger for allergy symptoms comes from grass pollens in the air. You don't see them, but they definitely find you. Merck (NYSE:MRK) thinks it might have a way to mow down these grass pollens.

The big pharmaceutical company, working with Danish partner ALK-Abello, developed MK-7243, an allergy immunotherapy tablet for Timothy grass pollen. MK-7243 uses what is known as sublingual allergy therapy -- taking medication under the tongue. It's more powerful than over-the-counter medications and more convenient than receiving shots.

This under-the-tongue approach has been available to allergy sufferers in Europe for a while now, but this will mark the first opportunity for approval in the U.S. The U.S. Food and Drug Administration accepted the Biologic License Application, or BLA, for review in March. Merck expects a decision by the FDA in the first quarter of 2014.

Weeding out ragweed
What about people who suffer from ragweed allergies instead of grass? Merck could have help on the way for them, too.

The company's allergy immunotherapy tablet for ragweed, dubbed MK-3461, works similarly to its grass pollen sibling. Immunotherapy claims a big advantage over other treatments. Rather than just relieving symptoms temporarily, it gradually desensitizes the immune system to the pollen that triggers the allergic reaction.

Merck submitted the BLA for MK-3461 in March. However, the FDA has not yet indicated if the information was complete enough to accept for review.

Reducing red-eye
If your eyes become itchy and tear up easily along with other allergy symptoms, you probably have an allergy-associated condition called allergic conjunctivitis. One drug in development might be able to clear those red eyes up, but don't count on its availability anytime soon.

Zalicus initially developed Prednisporin. The small biotech licensed the drug to Fovea Pharmaceuticals in 2006. Fovea was later acquired by French drugmaker Sanofi (NASDAQ:SNY). Clinical studies of Prednisporin conducted in 2009 and 2010 were very positive, but the drug seemed to languish after that point.

In October 2012, though, Sanofi announced that it had reassessed the potential for Prednisporin. That potential was seen as promising enough to move forward with a late-stage clinical study. The catch was that Sanofi intends to sublicense the drug to a third party, which has yet to be identified. Now it's a waiting game for a phase 3 trial to begin.

Real opportunities
Merck and Sanofi have both seen significant success with products such as Singulair, Clarinex, and Allegra. These newer experimental drugs, especially the allergy immunotherapy tablets from Merck, could add to this success. The size of the allergy market is nothing to sneeze at.