How can I tell if he has allergies or just a lingering cold?

1. Have the seasons changed? If yes, it could be allergies. Seasonal allergies come at the same time every year and around the same set of circumstances, like when leaves start to fall or plants start to flower. Allergy symptoms like sneezing, congestion, or a runny nose are the body's response to breathing in allergens (like plant pollen or mold spores) that are released into the air. Colds, on the other hand, are caused by viruses that can turn up in any environment, during any time of year, but are more common in winter months.
2. Did symptoms come on suddenly? If yes, it could be allergies. Another indicator that you might be dealing with seasonal allergies is if symptoms come on suddenly and last a long time. Cold symptoms tend to come on more gradually and typically go away within 7 to 10 days, but allergies last as long as someone is exposed to an allergen, which can be for weeks or months.
3. Does your son have itchy, watery eyes? If yes, it could be allergies. Many kids with allergies get this symptom when an allergen causes an inflammation of the conjunctiva, a clear membrane that covers the inner eyelids and eyeball.
4. Is there an absence of fever and no yellow/greenish nasal discharge? If yes, it could be allergies. Allergy symptoms are never accompanied by a fever, while colds sometimes are. And with an allergy, your son's runny nose will have a thin, clear discharge, rather than the thick yellow or greenish discharge that can come with a cold.

If you suspect your son has an allergy, the only way to tell exactly what he's allergic to is to get an allergy test. This test can be performed on the skin (where an allergen is placed under the skin to check the body's response) or through a blood test.

If your son does have allergies, the doctor will recommend reducing exposure to the allergen and might also suggest an over-the-counter (OTC) or prescription allergy medication to relieve symptoms.

And if you determine that your son has a cold, check with the doctor before giving him OTC cold medicines. There is little-to-no evidence that they work and serious side effects are a risk, especially in younger children. Acetaminophen or ibuprofen can be given to relieve fever or pain.