CBS NEWS, NEW YORK — Ragweed season is upon us. Millions of Americans are allergic to these plants. In fact they're the number one cause of hay fever in the U.S. And this year, people may suffer more than ever.

Dr. Cliff Bassett, Long Island College Hospital:

"We're expecting one of the worst ragweed seasons in over 50 years."

A single ragweed plant contains a billion pollen grains, and they can travel up to 700 miles in the wind. Chances are, some of them will end up in your eyes, nose, mouth, and even your lungs.

And if you're allergic to ragweed pollen, you'll know right away.

Dr. Cliff Bassett:

"Stuffy nose, congested nose, and itchy eyes are up there as a top three symptoms in people who suffer from seasonal allergies."

Over-the-counter and prescription antihistamines and eye drops can help symptoms once they start. But allergists say starting preventive medications like nasal steroids and inhalers now can keep you from suffering later.

Ann Roland takes medications and gets weekly allergy shots. She says they've made a real difference.

Anne Roland, Allergy sufferer:

"The symptoms are less. Nasal, coughing, throat… it's all better."

And one more tip: certain foods like bananas, melons and cucumbers can trigger symptoms in people who suffer from ragweed allergies, so you may want to avoid them.