Symptoms of allergies depend upon the parts of the body that are targets for the immune response. Because allergic inflammation starts with a reaction between a seasonal allergen and IgE antibodies produced by your immune system, those areas that interface directly with your environment, such as the respiratory tract (nose, throat and lungs) and the skin, are the most prominent targets.
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Nasal symptoms include sneezing, runny or stuffy nose and nasal itching.
Involvement of sinuses may produce facial pain or headache and postnasal drip.
Allergy of the bronchial tubes and lungs produces cough (dry or wet), wheezing and shortness of breath (asthma).
When skin is a target, the symptoms include itching, redness, swelling and/or a scaly rash (eczema). The rash of eczema is often most intense in the creases of the elbows and knees, but may involve any area of the body.
The eyes are often involved in seasonal allergies, with itching, burning, tearing, redness and sometimes with swelling of the lids.
These symptoms are often associated with poor sleep and fatigue. Despite the name “hay fever,” getting a fever from seasonal allergies is rare.
Seasonal allergies may directly impair cognitive function and physical performance, according to experiments conducted in the U.S. and Europe.
In one study, people with pollen allergies were tested on a closed driving course out of season before and after being exposed to the pollen to which they were allergic. The impairment produced by pollen exposure was equivalent to that seen at a blood alcohol level of 0.05 percent, which most people get after two cocktails. In a similar experiment among U.S. veterans, pollen exposure had a major adverse impact on vigilance and response times and decreased the efficiency of working memory and the speed of reasoning and computation. The effect was comparable to taking a sedative drug. But this was not a drug effect. It was a direct effect of the allergy itself.
From the perspective of public health and safety, pollen allergy is a serious disease that affects 500 million people around the world and approximately 30 million people in the U.S. It needs to be taken seriously.
Distinguishing Allergy from Infection
Distinguishing between allergy and infection as a cause of symptoms is important because they are treated differently. Fever is uncommon with allergy, but frequently accompanies viral or bacterial infection.
With nasal allergy, the lining of the nose is typically swollen and pale or slightly cyanotic (blue-tinged), and nasal secretions are liquid and clear. This distinguishes nasal allergy from a viral cold, in which the nasal lining is typically red and appears inflamed.
With sinus allergy, the drip is clear, whereas with a sinus infection, the drip is thick and yellow or green in appearance.
With allergic bronchitis, any mucus produced by coughing is usually clear and stringy in consistency. With a bronchial infection, the mucus tends to be thick and opaque, with a color that can range from yellow to green or gray.
The rash of eczema is usually dry unless a secondary infection occurs, in which case it can be wet or have a honey-colored crust.