While many patients think they have allergic rhinitis, various conditions can cause similar symptoms, says Melbourne allergist Dr Celia Zubrinich, chair of the Australasian Society of Clinical Immunology, Allergy, Immunotherapy and Skin Testing Working Party.

She shares tips to help with diagnosis, including some common differentials.

What are the symptoms?

Symptoms provide key clues about whether an allergic process is occurring.

Typical allergic rhinitis symptoms

• Watery, runny nose especially anterior
• Sneezing
• Nasal congestion, usually bilateral (but can alternate between sides)
• Nasal itching (kids may tend to rub their noses upwards)
• May be accompanied by allergic conjunctivitis

Symptoms that suggest a non-allergic condition

• Often unilateral
• Nasal obstruction without other symptoms
• Thick, viscous, or purulent rhinorrhoea
• Post-nasal drip
• Pain and bleeding (although there may be some blood streaking in allergy if the nose is highly inflamed or irritated)
• Hyposmia or anosmia, particularly if persistent

Timing and triggers

“Think about when the patient is affected — springtime or all the time; only when they visit their cousin’s house where there’s a cat present — and how frequent the symptoms are,” Dr Zubrinich says.

Dust mite triggers can be tricky to recognise, but include emptying the vacuum bag, cleaning under the bed, moving house, or getting something out of a dusty cupboard.

“Cats, pets, horses, dogs, and springtime are usually easier to identify,” she adds, “although some people say springtime bothers them, but they’re really not quite certain when you follow them a bit more prospectively.”

Response to previous treatment

By the time someone comes in, they’ve likely tried over-the-counter treatments, so it’s important to review what they’ve already tried, Dr Zubrinich notes.

“Ask about what they’ve done so far, because if they’re just told to do the same thing again, and they’ve come to you because that was not successful, that will result in frustration and inefficient treatment.”

Testing

Skin prick and IgE/RAST blood testing are both diagnostically helpful and neither is superior, Dr Zubrinich says.

Skin prick testing allows you to assess multiple allergens at a time and get an immediate result. However, it requires skill and resources not always available in general practice, Dr Zubrinich says.

You can do blood tests for all the common allergens, including grass pollen, individual pollens or pollen mixes, dust mite, cat, and dog—although its usually limited to four allergens at a time, she advises.

“And this is highly reliable. If it’s positive, it’s meaningful. If it’s negative, we can rely on it also.”

RAST testing may be more suitable in people with severe skin disease or those taking antihistamine medications, or to get an IgE level without the risk of triggering a reaction (e.g. in latex or some food allergies).

Differential diagnosis

Several other conditions that are not difficult to diagnose can cause hay fever-like symptoms, Dr Zubrinich says.

Non-allergic rhinitis

This can be diagnosed in general practice with a good history and appropriate testing, she says. It is effectively a diagnosis of exclusion if testing for common and relevant allergens proves negative.

“It is also a constellation of several specific conditions,” Dr Zubrinich says.

These include:

• Vasomotor rhinitis – which people often attribute to pollen exposure (e.g. they get sniffly while running in cool air), but which is actually a vascular phenomenon
• Rhinitis of pregnancy – which often presents with congestion or discharge
• Rhinitis medicamentosa – a non-allergic subtype associated with prolonged reliance on decongestant nasal sprays
• Gustatory rhinitis – which occurs after eating hot or spicy foods.

Chronic rhinosinusitis

The symptoms of this inflammatory, non-seasonal and usually non-allergic condition can mimic those of allergic rhinitis.

“And it’s not rare for people to have both,” Dr Zubrinich says. “The important difference is thinking about the pathology and some of the symptomatology.”

Itching, sneezing and ocular symptoms are less common in chronic rhinosinusitis.

Nasal polyps occur in a subtype of this condition and often lead to anosmia, although “certain very potent smells may cut through.”

Nasal congestion and discharge, which may be watery or viscous, can also occur.

A non-contrast CT of the sinuses may show mucosal thickening and polypoidal growth diminishing the air spaces.

Structural problems

Issues such as a deviated nasal septum can contribute to symptom burden, Dr Zubrinich says.

“And often people won’t necessarily think that the asymmetry is the problem, but what they experience is nasal blockage. And it can be one side or both sides.”

It can sometimes be diagnosed on examination, or with an anterior rhinoscopy via otoscope or CT of the nose and sinuses.

Nasal endoscopy may be necessary, especially if surgery is being considered, and is usually performed by an ENT surgeon.

However, “a deviated nasal septum is not going to account for sniffling, sneezing, itching,” Dr Zubrinich notes.