Nasal allergies and sinus problems can cause similar symptoms: nasal congestion or runny nose, headaches, decreased smell, cough, and sore throat. Deciding whether these symptoms are due to allergic rhinitis--nasal allergies, or sinusitis-- inflammation of the sinus, can be challenging. Luckily, some important historical elements can help make the diagnosis.
Allergic Rhinitis
Allergies occur when the immune system overreacts to factors in the environment that do not pose a serious risk like dust mites, pollen, grass, and animal dander. In allergic rhinitis, the immune cells in the nose release inflammatory molecules in response to these triggers. This inflammatory reaction is responsible for causing the production of mucus, which causes runny nose. Mucus also leaks down the back of the throat, which translates into sore throat and cough. Alternatively, allergic inflammation can cause the nasal lining to swell, leading to nasal congestion, or stuffy nose.
Sinusitis
Sinusitis is inflammation of the sinuses, which are pockets of air in the bones of the forehead and checks. The sinuses drain into the nose, and inflammation of the sinus cavities can lead to mucus production that then drains from sinus to nose to nasal opening and throat. There are two types of sinusitis: acute and chronic. Acute sinusitis is caused by a viral or bacterial pathogen entering the sinus and causing an immune response. Chronic sinusitis, which is sinusitis lasting more than eight weeks, can be due to an infection or to a mechanical blockage of the sinus outlet by something in the nose such as a polyp or a deviated septum.
Symptoms Specific to Allergies
The inflammation that develops in allergies is due to a specific type of immune system response featuring eosinophils, an antibody called IgE, and mast cells. Histamine released by mast cells causes itchiness, so itchiness points to allergies. Furthermore, allergies occur in response to an environmental trigger. Symptoms that occur only after to exposure to a specific scenario, for example being around a cat, or symptoms that occur during a particular time period, such as ragweed season in late summer, are more consistent with allergic disease than sinusitis.
Symptoms Specific to Sinusitis
Sinuses are air cells surrounded by bone. If the lining becomes inflamed, the bone will not yield to it, and the pressure in the sinus will increase. This pressure causes a feeling of deep, boring pain over the sinuses. Pain in the forehead above the inner half of the eyebrows, or in the cheeks near the bridge of the nose, is more consistent with sinusitis than allergies. Fever is another distinguishing sign of sinusitis, related to the inciting infection.
