Sneezing and runny noses are the most common indication of allergies. Only a small percentage produce a headache as the primary symptom. Sometimes the allergen will be something you inhale, like strong perfume, but food allergies are more common.

Like a toppling line of dominoes, one allergic reaction can lead to another. If you've ever suffered hay fever or other allergies, you know that the sinuses are the first to go.

Hay isn't the issue. Your eyes are red; your nose is running; your head is stopped up. Fever is the least of your problems. Still, it's called hay fever.

Ragweed and old' Rover have one thing in common: if you're allergic, they can trigger any number of reactions ranging from a congested, runny nose to red, swollen eyes.