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. If you get a headache every time you eat a certain food, an allergy may be the cause. The best way to track this phenomenon is to keep a food diary. When a certain meal produces a headache, make a note of all the foods you consumed. Eventually, you'll be able to narrow the field down to the foods you're allergic to. Some of the more widespread food allergies are milk, eggs, wheat, nuts, shellfish, or chocolate. You can then avoid that particular food. Visit an allergy specialist and have a series of tests to determine your allergies, and undergo treatment to desensitize your system to these foods or substances. For more information, contact an ear, nose and throat specialist in your area.