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PubMed This is a summary of 14 peer-reviewed journal articles Updated
Allergy and Immunology

Spotting the Signs: Symptoms and Red Flags

At a Glance

Allergic rhinitis typically causes symptoms on both sides of the nose, including sneezing, congestion, and itchy eyes. Symptoms affecting only one side of the nose, recurrent nosebleeds, severe facial pain, or a complete loss of smell are clinical red flags that require professional medical evaluation.

Recognizing the symptoms of Allergic Rhinitis (AR) is the first step toward finding relief. While many people think of allergies as a simple nuisance, the immune response—driven by IgE-mediated inflammation—can cause a wide range of bothersome and even debilitating symptoms [1].

Hallmark Symptoms of Allergic Rhinitis

True allergic rhinitis typically presents with a “cluster” of symptoms that affect both sides of the nose and often the eyes. These include:

  • Sneezing and Itching: Frequent, often repetitive sneezing and an itchy nose, throat, or roof of the mouth [2].
  • Nasal Congestion: A “stuffy” feeling caused by swollen tissues in the nasal passages [2].
  • Rhinorrhea: A clear, watery nasal discharge (runny nose) [2].
  • Ocular Symptoms: Red, itchy, or watery eyes (allergic conjunctivitis) [2].

When It Is NOT Allergic Rhinitis: Clinical “Red Flags”

It is vital to distinguish AR from other, more serious conditions. If you experience any of the following red flag symptoms, they may indicate a different diagnosis—such as a structural issue, a specialized infection, or a benign growth—and you should seek a medical evaluation promptly:

Red Flag Symptom Potential Concern
Unilateral Symptoms Congestion or discharge that only occurs on one side of the nose can suggest a deviated septum, a foreign object, or a benign growth [3].
Epistaxis (Nosebleeds) Occasional mild nosebleeds are common due to nasal dryness, rubbing, or as a side effect of nasal sprays. However, recurrent, persistent, or profuse bleeding is not typical for AR and requires investigation [4][5].
Anosmia (Loss of Smell) While allergies can dull your sense of smell, a complete loss of smell (especially without congestion) needs investigation to rule out other causes [6].
Clear Unilateral Leak A constant, clear, watery leak from only one nostril—particularly when leaning forward—could, in very rare cases, be a Cerebrospinal Fluid (CSF) leak [7].
Severe Facial Pain Intense pain, pressure, or swelling in the face and changes in vision (like double vision) are signs that require immediate attention [8].

Impact on Sleep and Daily Life

Allergic rhinitis is a systemic condition that “follows you to bed.” The inflammation in your nasal passages can significantly disrupt your sleep architecture, leading to fragmented sleep [9]. This disruption often causes:

  • Daytime Dysfunction: You may wake up with morning headaches or feel a deep sense of exhaustion regardless of how long you slept [9][10].
  • Reduced Productivity: The combination of poor sleep and “brain fog” leads to presenteeism—being at work or school but unable to perform effectively [1][11].
  • Breathing Issues: In children especially, AR is linked to sleep-disordered breathing, which can affect growth and school performance [12][13].

Treating the nasal obstruction associated with AR has been shown to improve subjective sleep quality, helping you feel more rested and alert during the day [14].

Common questions in this guide

Is it normal for allergies to only affect one side of my nose?
No, true allergic rhinitis typically affects both sides of the nose. Congestion or discharge on just one side is a red flag that could suggest a structural issue, like a deviated septum, or a benign growth that needs medical evaluation.
Can allergic rhinitis cause nosebleeds?
Occasional mild nosebleeds can happen from nasal dryness, rubbing, or using certain nasal sprays. However, recurrent, persistent, or heavy bleeding is not a typical allergy symptom and should be investigated by a doctor.
Why do my allergies make me feel so tired and unfocused during the day?
Nasal congestion and inflammation can significantly disrupt your nighttime breathing, leading to fragmented and poor-quality sleep. This sleep deprivation often causes daytime exhaustion, morning headaches, and difficulty concentrating.
Can seasonal allergies cause a complete loss of smell?
While nasal congestion can temporarily dull your sense of smell, a complete loss of smell (anosmia) is not a standard allergy symptom. You should consult a healthcare provider to investigate other potential causes.
What does it mean if I have a constant clear fluid leaking from one nostril?
A continuous clear, watery leak from only one side of the nose, especially when leaning forward, is a clinical red flag. In rare cases, this could indicate a cerebrospinal fluid leak and requires prompt medical attention.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Based on my symptoms, is it possible that I have a structural issue, like a deviated septum, rather than just allergies?
  2. 2.Since my symptoms are mostly on one side, should we consider imaging or a nasal endoscopy to rule out other causes?
  3. 3.How can we tell if my loss of smell is due to temporary swelling or something more permanent?
  4. 4.My sleep is very fragmented; are there specific treatments that focus on improving nighttime breathing and sleep quality?
  5. 5.Are the 'brain fog' and morning headaches I'm feeling a direct result of my nasal congestion?

Questions For You

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References

References (14)
  1. 1

    Allergic Rhinitis.

    Kakli HA, Riley TD

    Primary care 2016; (43(3)):465-75.

    PMID: 27545735
  2. 2

    Allergic Rhinitis: A Review.

    Bernstein JA, Bernstein JS, Makol R, Ward S

    JAMA 2024; (331(10)):866-877 doi:10.1001/jama.2024.0530.

    PMID: 38470381
  3. 3

    The prevalence of non-allergic rhinitis phenotypes in the general population: A cross-sectional study.

    Avdeeva KS, Fokkens WJ, Segboer CL, Reitsma S

    Allergy 2022; (77(7)):2163-2174 doi:10.1111/all.15223.

    PMID: 35038765
  4. 4

    An Unveiling of the Misdiagnosis of Granulomatosis with Polyangiitis as Acute Sinusitis: A Case Report.

    Wang Q, Ling Y, Huang Y, et al.

    Diagnostics (Basel, Switzerland) 2025; (15(17)) doi:10.3390/diagnostics15172218.

    PMID: 40941705
  5. 5

    Dysphagia due to oesophageal obstruction: A case report of unusual occupational aetiology.

    Makaram N, Gohil R, Majumdar S

    Annals of medicine and surgery (2012) 2015; (4(4)):438-43 doi:10.1016/j.amsu.2015.10.014.

    PMID: 26693007
  6. 6

    Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study.

    Lechien JR, Chiesa-Estomba CM, De Siati DR, et al.

    European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery 2020; (277(8)):2251-2261 doi:10.1007/s00405-020-05965-1.

    PMID: 32253535
  7. 7

    Spontaneous Cerebrospinal Fluid Rhinorrhea in Pre-operative Pituitary Adenoma: A Report of Two Cases.

    Eisold JE, Dimante D, Pollock J, et al.

    Cureus 2024; (16(10)):e71642 doi:10.7759/cureus.71642.

    PMID: 39553112
  8. 8

    Diagnosis of Sinonasal Carcinoma in the Emergency Department: A Case Report Highlighting Red Flag Symptoms.

    Usuga D, Osunjima A, Danko C

    Journal of education & teaching in emergency medicine 2026; (11(2)):V35-V40 doi:10.5070/M5.52257.

    PMID: 42110684
  9. 9

    The association between allergic rhinitis and sleep: A systematic review and meta-analysis of observational studies.

    Liu J, Zhang X, Zhao Y, Wang Y

    PloS one 2020; (15(2)):e0228533 doi:10.1371/journal.pone.0228533.

    PMID: 32053609
  10. 10

    Association between symptoms of allergic rhinitis with decreased general health-related quality of life.

    Hoehle LP, Speth MM, Phillips KM, et al.

    American journal of rhinology & allergy 2017; (31(4)):235-239 doi:10.2500/ajra.2017.31.4444.

    PMID: 28716174
  11. 11

    Costs of perennial allergic rhinitis and allergic asthma increase with severity and poor disease control.

    Belhassen M, Demoly P, Bloch-Morot E, et al.

    Allergy 2017; (72(6)):948-958 doi:10.1111/all.13098.

    PMID: 27886386
  12. 12

    Allergic rhinitis in children in relation to sleep breathing disorders: a meta-analysis.

    Li Q, Zhong Q, Kong X, et al.

    International journal of pediatric otorhinolaryngology 2026; (207()):112902 doi:10.1016/j.ijporl.2026.112902.

    PMID: 42302637
  13. 13

    Allergic Rhinitis in Children and Adolescents.

    Schuler Iv CF, Montejo JM

    Pediatric clinics of North America 2019; (66(5)):981-993 doi:10.1016/j.pcl.2019.06.004.

    PMID: 31466686
  14. 14

    Impact of Treatment for Nasal Cavity Disorders on Sleep Quality: Systematic Review and Meta-analysis.

    Fried J, Yuen E, Zhang K, et al.

    Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery 2022; (166(4)):633-642 doi:10.1177/01945998211029527.

    PMID: 34253107

This page provides educational information about allergic rhinitis symptoms and warning signs. It does not replace a professional medical diagnosis or advice from your healthcare provider.

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