Allergic rhinitis is an allergic reaction of the nose that happens when you breathe allergens like weed pollens, animal dander, and house dust, etc...

Most people confuse it with rhinosinusitis which is an inflammation of the sinus lining membrane and nasal mucosa due to anything that interferes with airflow into the sinuses and the drainage of mucous out of the sinuses.

Epidemiology

According to American Academy of Allergy, Asthma & Immunology, 10 to 30% of the world population may have Allergic rhinitis. While sinusitis affects approximately 12.5% of people.

Environmental pollution plays a big role in both allergic rhinitis and rhinosinusitis. Air polluted by cigarette smoke plays a big role in causing allergic rhinitis and rhinosinusitis for both active and passive smokers. As shown in this article review PMID: 22487789 [Indexed for MEDLINE]

Pathophysiology

Allergic rhinitis as we have seen is due to allergic reaction. After the exposure to allergens, an allergic response can be divided into 2 phases; early and late stage.

Early stage
Immediately after the exposure, the immune system will overreact to allergens by producing Immunoglobulin E (IgE). Antibody IgE will traverse the nasal epithelium where it recognizes allergens. By recognizing allergens it will release granules (degranulation) which include histamine, tryptase, chymase, heparin and other enzymes.

Mast cells will also release other inflammatory mediators like prostaglandin D2 and the leukotrienes LTD4, LTE4 and (LT)C4.

This is what all those mediators will do:

1. Blood vessels leakage which will cause the mucosal edema and watery mucus release within the nose.
2. Glands will secrete antimicrobial compounds together with mucoglycoconjugates and cause vasodilation which in turn convey to the sinusoidal filling. Thus nasal congestion and blockage.
3. Stimulation of sensory nerves by mediators will cause nasal itching and congestion, systemic reflexes like sneezing.

Late-stage
Mast cell-derived mediators that have been released in the early stage act on postcapillary endothelial cells where they promote the expression vascular cell adhesion molecule and E-selectin.

Adhesion molecules and E-selectin will facilitate circulating leucocytes to adhere to the endothelial cells. Cytokines IL-5 will attract eosinophils, neutrophils, basophils, T lymphocytes, and macrophages to infiltrate into the mucosa.
These inflammatory cells will be activated within 4-8 hours after exposure.

T-helper lymphocytes are the cause of chronic inflammatory response. They also release cytokines and other cells that may circulate to the hypothalamus and cause irritation, malaise, and fatigue.

Sinusitis

Sinusitis may be acute when symptoms are there less than 4 weeks, subacute when a patient is symptomatic from 4-8 weeks and chronic when symptoms have been there for more than 8 weeks.

Sinusitis is an inflammation of the sinus that can be caused by anything that can block sinus drainages and airflow. Sinusitis can occur together with nose inflammation (rhinitis) thus rhinosinusitis.
Sinusitis mostly happens into maxillary and anterior ethmoidal sinuses which drain into middle meatus. Maxillary sinus drains against the law of gravity which makes maxillary sinusitis worse.

This is usually what happens when sinus drainage and airflow are blocked:

1. Sinus hypoxia(lack of oxygen).
2. Mucus retention within the sinus cavity.

The above will cause an increase in bacteria growth, mucosal hyperplasia, and an increase in inflammatory infiltrates.
When symptoms persist for more than 8 weeks there will be more inflammatory infiltrates (pus) which lead to heavy head, bad breath, discomfort and chronic headache. Chronic sinusitis may lead to nasal polyps (finger-like projections in the nose).

Causes

Allergic rhinitis
Rhinitis itself is an inflammation of the nose. And when that inflammation happens as a result of an allergic reaction it is called allergic rhinitis.
Allergic rhinitis is caused by the breath of outdoor, external or seasonal allergens like weed pollens or grasses and in this case, it is called hay fever (seasonal allergy). It can also be caused by pet dander, cat saliva, and house dust mites (Perennial rhinitis).

Sinusitis
Sinuses are air-filled cavities in a dense portion of a skull bone. They are lined by ciliated pseudostratified columnar epithelium which helps them to trap dust in the air and drain them out of sinus together with mucus.

So anything that can interfere with airflow into the sinus and the drainage of mucus out of the sinus is the cause of sinusitis. The failure of a Sinus to drain mucus will lead to the growth of germs within the sinus resulting in an infection. And the body will respond with an inflammation (sinusitis). It may be chronic (more than 8weeks) or acute (up to 4weeks).

Things that interfere with sinus drainage and airflow are allergic rhinitis, nasal polyps, common cold, pacifiers, bottle drinking while lying on the back and structural differences that narrow or block drainage ducts.

Sinusitis can also be caused by smoking and immunosuppressor drugs or diseases.

Symptoms

Allergic rhinitis	Sinusitis
Fatigue	Fatigue
Sneezing
Runny, itchy and stuffy nose	Runny, stuffy nose, congestion
Coughing	Cough worse at night
Sore throat	Sore throat
Itchy and watery eyes
Hives	Fever
Headache	Localized facial pain exacerbated by bending over or lying down
	Dental pain
	Bad breath and loss of smell
	Thick, green, or yellow nasal discharge

Chronic sinusitis may include pus in the nasal cavity and discolored postnasal discharge.

Diagnosis

The key to diagnose allergic rhinitis and rhinosinusitis is to be familiar with signs and symptoms differences.

Allergic rhinitis

Hay fever (seasonal allergic rhinitis) is easy to identify due to its acute onset after exposure to allergens.
Perennial allergic rhinitis due to its similarity to acute sinusitis, respiratory infections, and vasomotor rhinitis is more difficult to diagnose. And in this case, IgE antibody tests to detect specific allergens will be used.

Rhinoainusitis

In addition to clinical signs and symptoms, some diagnostic tools like X-ray, CT scan or MRI will be used especially for chronic Rhinosinusitis.

This radiograph is showing an inflammation (pus accumulation and thickened mucosa) of the left maxillary sinus. On clearer radiograph you will observe a crescent 🌙 that is more radiopaque (whiter) than air (on radiograph) which shows pus accumulation.

_{Image by NIAID, Wikimedia Creative Commons (Attribution 2.0 Generic)}

Hope this image is larger enough to show the structures. It is a CT scan image showing normal and inflamed frontal, ethmoid and maxillary sinuses. Here the most features that are showing sinusitis are thickened mucosa and blocked ethmoid sinus.

Treatment

Allergic Rhinitis

For mild and moderate allergic rhinitis,

Intranasal corticosteroids are recommended. These steroids are sprayed or inhaled into the nose. And they will relieve the stuffy nose, irritation, and discomfort.

For moderate and severe cases oral and topical antihistamines will be used. Histamine is released during inflammation, so anti-histamine drugs will relieve inflammatory reactions like itching and eczema.

When the patient doesn't respond to oral and topical antihistamines, an allergist may recommend allergy shots also known as subcutaneous immunotherapy (SCIT). These are like vaccines, your body is given specific allergens in an increasing way to the level it becomes resistant or tolerant to that allergen.

Decongestants and eye drops can be used to relieve symptoms (stuffy, etching eye respectively).

Sinusitis

Pharmacotherapy
Medicines may vary depending on the cause of sinusitis.

• Antibiotics for sinusitis of bacterial origin.
  Here you're given broad-spectrum antibiotics for 10-14 days.

• If Rhinosinusitis is of viral origin like the common cold, Antivirals are needed to treat the cause and viral infection within the sinus.

• If it is a fungal infection, antifungals will be the drug of choice.

• Antihistamines if sinusitis is of allergic origin. Sinusitis caused by allergic rhinitis is a good example of where Antihistamines will be needed.

• Decongestants: to relieve stuffy nose and open nose airways.

• NSAIDs: to relieve an inflammatory pain.

• Normal saline to wash the nose.

Home care

• Breathing steam vapors: here you put warm water in a bowel then cover yourself over the bowel for 30 mins. This method is effective to relieve stuffy nose and help sinus drainage due to mucus dilatation and come out easily. I myself use this method.

• Putting a warm wet towel on your face can reduce pressure as it causes mucus dilatation

• Enough rest is necessary.

• Stop alcohol as it increases swelling, mucosal thickening.

• Increase fluids intake as they will help to reduce the sinus blockage by thinning the mucous membrane.

Other Therapy include surgery for recurrent sinusitis, chronic sinusitis with nasal polyps and sinusitis due to structural differences that narrow or block drainage ducts.

For prevention of both Allergic rhinitis and sinusitis (when you're allergic):

🚩 Stay away from allergens.
🚩 Wash your hands often.
🚩 Don't smoke and avoid indirect smoking.
🚩 Don't exercise outside early morning.
🚩 Remove carpets in your bedroom if you suspect dust mites.
🚩 Cover your mouth and nose while performing yard work.
🚩 Wear sunglasses or eye protectors (googles) whenever it is necessary.

It is always advertised to consult your physician before any decision to your situation.

👎OTC (over the counter) decongestants took more than 3 days can increase congestion.

🚨 Where terms Rhinosinusitis and sinusitis have been used in this article, know that :

• Rhinosinusitis: is an inflammation of both nose and sinus.
• Sinusitis is an inflammation of Sinus alone though it may be used to mean rhinosinusitis.
• Rhinosinusitis can be called sinusitis but never sinusitis alone called rhinosinusitis.

References

1. WHO.int: Chronic respiratory diseases
2. WebMD:Sinusitis
3. WebMD: Sinusitis Treatment
4. American College of allergy, Asthma & Immunology: Hay fever
5. American family physician: Allergic rhinitis therapy
6. Healthline: Allergic rhinitis
7. Wikipedia: Sinusitis.
8. jacionline.org : Allergic rhinitis
9. Cleveland Clinic

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Thank you for your time reading!

By Jado

@bmotives

SHALLOM

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