Allergic Rhinitis

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Last updated: April 27, 2026Bookmark

Allergic rhinitis is a type I hypersensitivity reaction characterized by sneezing, nasal congestion, clear rhinorrhoea, pruritus, and postnasal drip. It is associated with asthma, conjunctivitis, and atopic dermatitis (unified airway concept).

It peaks in adolescence and young adulthood, and affects women more than men.

Combined classification (ARIA)

  • Intermittent mild
  • Intermittent moderate-severe
  • Persistent mild
  • Persistent moderate-severe

Classification based on duration

ClassificationDescription
Intermittent (seasonal)Cyclical symptoms occurring < 4 days per week or < 4 consecutive weeks. It is triggered by pollens.
Persistent (perennial)All year-round symptoms (≥ 4 days per week and ≥ 4 weeks). It is triggered by indoor allergens such as dust mites, animal dander, and mould.

Classification based on severity

SeverityDescription
MildNormal sleep, daily activities, and work/school performance. The symptoms are not troublesome.
Moderate-SevereOne or more of: sleep disturbance, impaired daily activities, impaired school/work, or troublesome symptoms.

Early vs. delayed phase of the allergic response

Acute (early phase)Late (delayed phase)
OnsetImmediate, 5- 30 mins2- 8 hours after exposure to allergen without additional exposure
CauseHistamine releaseInfiltration of immune cells
Clinical featuresSneezing, rhinorrhea, nasal blockage, and bronchospasmSwelling, congestion, and thick secretions in the airway
  • Risk factors
    • Family history of atopy
    • High IgE levels
    • Early-life exposures, e.g., smoke
  • Associated conditions
  • Pathophysiology
    • Early phase (minutes)
      • Allergy exposure → mast cell degranulation and release of histamine → sneezing, rhinorrhea and itching
    • Late phase (4 – 6 hours)
      • Cytokines (IL-4 and IL-13) → eosinophil and T-cell infiltration → persistent inflammation and nasal congestion
    • Chronic inflammation → nasal hyperreactivity to non-specific triggers, e.g., cold air and smoke
  • Signs and symptoms
    • Nasal itching
    • Sneezing
      • Paroxysmal
      • 10-20 at a time
    • Rhinorrhea
      • Watery
    • Nasal congestion
    • Conjunctivitis
    • Itching of the palate, pharynx or ear
    • Postnasal drip
    • Cough
  • Physical examination
    • Transverse nasal crease (allergic salute) due to constant rubbing
    • Pale and edematous nasal mucosa
    • Swollen turbinates
    • Allergic shiners (dark circles under the eyes)
    • Congestion and cobblestone appearance of the conjunctiva
  • Differentials
    • Non-allergic rhinitis
    • Vasomotor rhinitis
    • Infective sinusitis
  • Investigations
    • Allergen testing (IgE or skin tests) if needed
    • Imaging tests are not routine
  • Treatment
    • Avoid triggers
    • Antihistamines for mild-to-moderate symptoms
      • Second-generation antihistamines are preferred since they have less sedation
    • Intranasal corticosteroids for moderate-to-severe symptoms
      • These are the most effective treatment
    • Leukotriene receptor antagonists (adjunct)
    • Immunotherapy (subcutaneous or sublingual) for severe or refractory cases
    • Short course of oral corticosteroids can be given to cover important life events
    • Short course of decongestants due to tachyphylaxis and rhinitis medicamentosa
    • Nasal saline
  • Complications
    • Bronchial asthma
    • Recurrent sinusitis due to obstruction of sinus ostia
    • Nasal polyps
    • Serous otitis media
    • Orthodontic problems due to prolonged mouth-breathing in children
Reference Intervals ›
Biochemistry
ACTHP: <80 ng/L
ALTP: 5–35 U/L
AlbuminP: 35–50 g/L
AldosteroneP: 100–500 pmol/L
Alk. phosphataseP: 30–130 U/L
α-AmylaseP: 0–180 IU/dL
α-FetoproteinS: <10 kU/L
Angiotensin IIP: 5–35 pmol/L
ADHP: 0.9–4.6 pmol/L
ASTP: 5–35 U/L
BicarbonateP: 24–30 mmol/L
BilirubinP: 3–17 μmol/L
BNPP: <50 ng/L
CRPP: <10 mg/L
CalcitoninP: <0.1 mcg/L
Calcium (ionized)P: 1.0–1.25 mmol/L
Calcium (total)P: 2.12–2.60 mmol/L
ChlorideP: 95–105 mmol/L
CholesterolP: <5.0 mmol/L
VLDLP: 0.128–0.645 mmol/L
LDLP: <2.0 mmol/L
HDLP: 0.9–1.93 mmol/L
Cortisol AMP: 450–700 nmol/L
Cortisol MidnightP: 80–280 nmol/L
CK ♂P: 25–195 U/L
CK ♀P: 25–170 U/L
CreatinineP: 70–100 μmol/L
FerritinP: 12–200 mcg/L
FolateS: 2.1 mcg/L
FSHP: 2–8 U/L ♂; >25 menopause
GGT ♂P: 11–51 U/L
GGT ♀P: 7–33 U/L
Glucose (fasting)P: 3.5–5.5 mmol/L
Growth hormoneP: <20 mu/L
HbA1C (DCCT)B: 4–6%
HbA1C (IFCC)B: 20–42 mmol/mol
Iron ♂S: 14–31 μmol/L
Iron ♀S: 11–30 μmol/L
Lactate (venous)P: 0.6–2.4 mmol/L
Lactate (arterial)P: 0.6–1.8 mmol/L
LDHP: 70–250 U/L
LHP: 3–16 U/L
MagnesiumP: 0.75–1.05 mmol/L
OsmolalityP: 278–305 mosmol/kg
PTHP: 0.8–8.5 pmol/L
PotassiumP: 3.5–5.3 mmol/L
Prolactin ♂P: <450 U/L
Prolactin ♀P: <600 U/L
PSAP: 0–4 mcg/mL
Protein (total)P: 60–80 g/L
Red cell folateB: 0.36–1.44 μmol/L
Renin (erect)P: 2.8–4.5 pmol/mL/h
Renin (recumbent)P: 1.1–2.7 pmol/mL/h
SodiumP: 135–145 mmol/L
TBGP: 7–17 mg/L
TSHP: 0.5–4.2 mU/L
T4P: 70–140 nmol/L
Free T4P: 9–22 pmol/L
TIBCS: 54–75 μmol/L
TriglyceridesP: 0.50–2.3 mmol/L
T3P: 1.2–3.0 nmol/L
Troponin TP: <0.1 mcg/L
Urate ♂P: 210–480 μmol/L
Urate ♀P: 150–390 μmol/L
UreaP: 2.5–6.7 mmol/L
Vitamin B12S: 0.13–0.68 nmol/L
Vitamin DS: 50 nmol/L
Arterial Blood Gases
pH7.35–7.45
PaCO₂4.7–6.0 kPa
PaO₂>10.6 kPa
Base excess±2 mmol/L
Urine
Cortisol (free)<280 nmol/24h
Hydroxyindole acetic acid16–73 μmol/24h
Hydroxymethylmandelic acid16–48 μmol/24h
Metanephrines0.03–0.69 μmol/mmol cr.
Osmolality350–1000 mosmol/kg
17-Oxogenic steroids ♂28–30 μmol/24h
17-Oxogenic steroids ♀21–66 μmol/24h
17-Oxosteroids ♂17–76 μmol/24h
17-Oxosteroids ♀14–59 μmol/24h
Phosphate (inorganic)15–50 mmol/24h
Potassium14–120 mmol/24h
Protein<150 mg/24h
Protein/creatinine ratio<3 mg/mmol
Sodium100–250 mmol/24h
Haematology
WCC4.0–11.0 ×10⁹/L
RBC ♂4.5–6.5 ×10¹²/L
RBC ♀3.9–5.6 ×10¹²/L
Hb ♂130–180 g/L
Hb ♀115–160 g/L
PCV ♂0.4–0.54 L/L
PCV ♀0.37–0.47 L/L
MCV76–96 fL
MCH27–32 pg
MCHC300–360 g/L
RDW11.6–14.6%
Neutrophils2.0–7.5 ×10⁹/L (40–75%)
Lymphocytes1.0–4.5 ×10⁹/L (20–45%)
Eosinophils0.04–0.44 ×10⁹/L (1–6%)
Basophils0–0.10 ×10⁹/L (0–1%)
Monocytes0.2–0.8 ×10⁹/L (2–10%)
Platelets150–400 ×10⁹/L
Reticulocytes0.8–2.0% / 25–100 ×10⁹/L
Prothrombin time10–14 s
APTT35–45 s
Paediatric
Pulse Rate (bpm)
Neonate140–160
Infant <1yr120–140
1–5 years110–130
5–12 years80–120
>12 years70–100
Respiratory Rate (tachypnoea)
0–2 months≥60/min
2–12 months≥50/min
1–5 years≥40/min
>5 years≥30/min
Blood Pressure (mmHg)
Term65/45
1 year75/50
4 years85/60
8 years95/65
10 years100/70
Weight Formulas
3–12 months(a + 9)/2 kg
1–6 years2a + 8 kg
>6 years(7a − 5)/2 kg
Haemoglobin (g/dL)
Term newborn13–20
1 month11–18
2 months10–15
1–2 years10–13
>2 years11–14
MUAC (6 months–5 years)
Obese>17.5 cm
Normal13.5–17.4 cm
At risk12.5–13.4 cm
Moderate malnutrition11.5–12.4 cm
Severe malnutrition<11.5 cm
Developmental Milestones
Social smile1.5 months
Head control4 months
Sits unsupported7 months
Crawls10 months
Stands unsupported10–12 months
Walks12–13 months
Talks18 months
CSF WBC (/mm³)
Term newborn0–25
>2 weeks0–5
Calculator ›

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