The most common causes of headache in allergic people are the ones found in the general population. Tension, for example, often causes headaches in both allergic and non-allergic people. Headaches due to tension or stress often involve tenderness of the muscles of the neck and shoulders. They tend to project from the back of the skull toward the front. Unusual sensitivity to light may accompany them. Stress, noise, strong odors and irritants such as tobacco smoke or exhaust often aggravate them. In young women, stress headaches may be more common during the premenstrual period.
Migraine is another common headache. Migraine headaches run in families and occur much more frequently among women. Some migraines are triggered by foods, but it’s doubtful they are caused by a true allergy. Some migraine headaches involve blind spots, nausea and vomiting. Anyone with recurrent, severe migraine headaches should receive a complete neurological evaluation.
Cluster headaches occur most often in men. These headaches tend to center around the eyes. They usually start within two to three hours of falling asleep. Pain can be intense, with tearing of the eyes, running of the nose, and flushing and swelling of the cheeks. The headaches may last one to two hours. These headaches tend to cluster, occurring frequently over a period of several weeks, then disappear. Stress or strong emotions can trigger recurrences.
Physical trauma also can cause headaches and especially should be considered when a child complains of head pain. (X-rays of the face, skull and spine may be appropriate.)
Exposure to environmental poisons is another important cause of headaches. Both smokers and those exposed to second-hand smoke frequently develop headaches from breathing the carbon dioxide in tobacco smoke. Defective furnaces can release carbon dioxide into the home or workplace, creating a risk not only of headache but of death. Working in a garage in which a car is idling or being stuck in a traffic jam also can give rise to a headache from carbon dioxide inhalation.
Specific foods or food ingredients may trigger some headaches and people often interpret this reaction as a symptom that they are allergic to that substance. Sulfites in wine, for example, cause headaches in some people, and tyramine in fermented cheeses cause headaches in others. However, it’s questionable whether such headaches are a true allergic reaction.
Caffeine withdrawal is another frequent cause of headache. People who are accustomed to consuming large amounts of caffeine in coffee, tea or soft drinks can develop an excruciating headache if they suddenly deprive themselves of the stimulant.
Illnesses and Medications
Sinusitis is a major cause of headache and should always be considered in people with allergic rhinitis. CAT scans, although expensive, give excellent information and can confirm a suspicion of chronic sinusitis. Antibiotic treatment for at least 21 days is necessary if chronic sinusitis is diagnosed.
Many teeth and gum problems can cause head pain. Any allergic person who suffers from chronic headaches should be evaluated by a dentist. The evaluation should include panoramic x-rays and a complete evaluation of the gums.
Many illnesses can also cause headaches. A complete physical examination will rule out potential causes of chronic headache such as high blood pressure, Cushing’s disease, hypothyroidism, acute anemia, Addison’s disease and others.
Medications prescribed for allergies sometimes cause headaches. Some antihistamines-loratadine, for example-have been associated with headaches. Oral decongestants commonly cause headaches. Nifedipine, a blood pressure medication, and ergot derivatives have been associated with vascular headaches. If headaches occur in people who take the asthma medication theophylline, blood levels of the drug should be obtained. Headaches are an early and accurate sign of theophylline overdosage. However, some people complain of headaches with theophylline even at very low doses, in which case alternative therapy should be considered.
Recurrent or chronic headaches should be evaluated by a physician. By identifying their cause, many headaches can be avoided. Those that can’t be prevented usually respond readily to acetaminophen (e.g., Tylenol).