While allergies and infections share some overlapping symptoms, understanding their distinctions is important for proper management.
Allergies and Body Temperature
Allergies typically do not cause a fever. The term “hay fever” is a misnomer, referring to seasonal allergies not associated with a rise in body temperature. Allergic reactions are a localized immune response where the body overreacts to harmless substances like pollen, dust mites, or pet dander. This overreaction involves the release of chemicals such as histamine, which causes symptoms like sneezing, itching, and congestion, but it does not trigger the release of pyrogens, the substances that cause fever.
Severe allergic reactions, known as anaphylaxis, have widespread effects but do not typically include fever as a primary symptom. Anaphylaxis involves a sudden drop in blood pressure and airway narrowing, which requires immediate medical attention. Prolonged inflammation from allergies, such as in hay fever, can sometimes create an environment that makes individuals more susceptible to secondary viral or bacterial infections, which can then cause a fever.
Other Causes of Fever
A fever indicates the body’s immune system has been activated to fight an infection. Normal body temperature varies, but a temperature of 100.0°F (37.8°C) or higher is generally considered a fever. Common causes of fever include viral infections like the common cold, influenza, or other respiratory viruses. These infections trigger the immune system to produce pyrogens, which signal the brain’s hypothalamus to raise the body’s temperature.
Bacterial infections are another frequent cause of fever. Examples include sinusitis, bronchitis, strep throat, and urinary tract infections. When bacteria invade, the immune system responds, leading to an elevated body temperature.
Differentiating Symptoms
Distinguishing between allergy and infection symptoms involves observing specific patterns. Allergies commonly present with clear, watery nasal discharge, itchy eyes, nose, or throat, and repetitive sneezing. These symptoms often lack body aches or significant fatigue and tend to persist as long as exposure to the allergen continues. Seasonal allergies, for instance, can last several weeks during pollen seasons.
In contrast, viral infections like a cold or flu typically involve thicker nasal discharge that may become discolored, a sore throat, cough, body aches, and noticeable fatigue. Fever is a common symptom of viral infections, often accompanied by chills and general weakness. Bacterial infections might also present with fever and other symptoms similar to viral infections but can sometimes be more severe or persistent, and may include localized pain or pus.
When to Seek Medical Advice
It is advisable to consult a healthcare professional if a fever persists beyond a few days or reaches 103°F (39.4°C) or higher in adults. Seek medical attention if the fever is accompanied by severe symptoms such as difficulty breathing, chest pain, a stiff neck, or severe headache. Confusion, extreme drowsiness, or a rash that does not fade when pressed are also signs that require immediate evaluation.
If symptoms worsen, do not improve, or if there is uncertainty about the cause of the fever, a medical professional can provide an accurate diagnosis. For severe allergic reactions like anaphylaxis, characterized by swelling of the face or throat, rapid pulse, or dizziness, immediate emergency medical help is essential.