While allergic rhinitis is often triggered by airborne allergens, the common cause of sinusitis is an infection. The onset of fever, a sign that your body is fighting off an infection, is a key indicator that you may be suffering from sinusitis rather than allergic rhinitis.

Furthermore, when you suffer from sinusitis, the build-up of mucus in the sinuses is likely to cause pressure or tenderness in the face. "However, if your eyes are watery and itchy, chances are you’re experiencing allergic rhinitis as itchiness is rarely a symptom of a sinus infection," say​ doctors from the ​​Department of Otolaryngology​ at Singapo​​re General Hospital​ ​(SGH), a member of the SingHealth​ group.​​

When it comes to treatment, there are differences between allergic rhinitis and sinusitis. In allergic rhinitis, to prevent allergy attacks, you need to minimise your exposure to allergens through frequent cleaning of living areas. If symptoms are intermittent, antihistamines are usually prescribed. A nasal steroid can be added should attacks become more frequent. For patients who fail to respond to conventional therapy, immunotherapy is another option.

As for acute sinusitis, it c​an be treated with antibiotics and decongestants. However, for chronic sinusitis – in cases where nasal obstructions cannot be reversed with medications – surgery may be required.

Ref: O17​