Americans who spend half their time sneezing, rubbing itchy eyes and wiping their noses know all too well the reality of hay fever and the allergies that strikes both in spring and fall. In the United States, it is estimated that a whopping 60 million people suffer from pollen allergies.

And where you have people irritated by allergies you can also have motorists who might be too drowsy to drive.

According to hay fever, some of the most pollen-heavy trees are Oak, Ash, Elm and Mountain cedar.

The pollen from these plants and more are potent at different times of the year and in different places. Some of the places which have trees with the highest pollen release in the western parts of the States would include Arizona, Idaho, Colorado, Washington, Utah and California. Here, trees like the juniper and acacia start flowering as early as December.

Clearly, many different allergies can strike at different times. Tree allergies are not found in the summer season. Western United States has a long grass pollen season from February through November. So does the South and the North.

But whether you're taking Alegra, Benadryl, Claritin...anything all the way to Zyrtec, the important thing is to remember to check the product's warning label.

News accounts about drivers compromised by their medications are increasing and that's because people are not taking enough time to understand the meds they're taking.

Antihistamines will make you drowsy. Here's just one example from what Zyrtec advises:

"Zyrtec may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Drinking alcohol can increase certain side effects of Zyrtec. Tell your doctor if you regularly use other medicines that make you sleepy (such as other cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by Zyrtec. Call your doctor if your symptoms do not improve, if they get worse, or if you also have a fever."