Seasonal allergies, though commonly known as hay fever, do not cause fevers. However, nasal congestion and other seasonal allergy symptoms can lead to infections, which may lead to raised temperatures.
Seasonal allergy symptoms include runny nose, itchy or watery eyes and nasal congestion.
Allergies are caused by the immune system overreacting to a harmless substance and producing histamines. Common triggers of seasonal allergies include pollen and mold.
Seasonal allergies do not cause fevers on their own, but chronic sinus congestion can lead to a bacterial sinus infection (sinusitis), which can cause fever—as well as symptoms such as nasal congestion, sinus pressure, headache and cough.
If what appears to be seasonal allergies causes general aches and pains, cough and sore throat, and a fever, it may actually be the common cold, a viral infection.
Treatment for seasonal allergies include antihistamines, decongestants and allergy shots. If you have a fever, consult your doctor, as you may need antibiotics to treat a sinus infection.