The Effect of Oral Probiotics on Allergic Rhinitis Symptoms and the Quality of Life

Allergic rhinitis (AR), also known as nasal allergy, hay fever or seasonal allergic rhinitis, is an inflammatory condition of the nasal passages caused by the immune system's response to allergens in the air. Symptoms include runny or blocked nose, nasal itching, sneezing, and red, itchy, and watery eyes. These symptoms typically occur within minutes of exposure to allergens and can affect sleep, work productivity, and concentration during learning. Many patients with allergic rhinitis also suffer from conditions such as asthma, allergic conjunctivitis, or atopic dermatitis.Symptoms in the majority of patients tend to recur and persist over time. While medication can alleviate the symptoms, complete cure is challenging to achieve.

Probiotics are generally defined as microorganisms that, when ingested, provide beneficial effects to the host. They primarily consist of bacteria that produce lactic acid, including Lactobacilli, Bifidobacteria, and Saccharomyces boulardii. One known mechanism underlying allergic diseases is the overactivation of Th2 cells, leading to an imbalance in the Th1/Th2 ratio. Previous research has explored whether the use of probiotics can prevent allergic diseases. Numbers of studies indicate that probiotics have the ability to modulate the immune system by increasing anti-inflammatory cytokines such as IFN-γ, IL-10, and IL-12 to enhance Th1 cell activity. Simultaneously, they suppress pro-inflammatory cytokines like IL-4, IL-5, and IL-13, inhibiting excessive Th2 activation and restoring Th1/Th2 balance to improve symptoms.

Current evidence from clinical randomized controlled trials suggests that supplementation with probiotics during pregnancy and early infancy can prevent allergies or the development of more severe allergic conditions. However, regarding AR, current research has confirmed that probiotic consumption can improve the quality of life and the severity of nasal symptoms (measured by PRQLQ and TNSS) in AR patients. Nevertheless, the efficacy of regulating AR varies based on different strains or species of probiotics used.

This project aims to select probiotic strains that enhance the function of regulatory T cells (Treg cells), thereby promoting the secretion of Th1 cell cytokines IL-12 and IFN-γ to assist in achieving Th1/Th2 immune balance. This approach aims to reduce specific immunoglobulin E (IgE) levels and achieve an anti-inflammatory effect, thereby improving the regulation of allergic reactions within patients' bodies.

Study Overview

• Status: Active, not recruiting
• Conditions: Allergic Rhinitis
• Intervention / Treatment: Dietary supplement: Lactobacillus rhamnosus F-1; Dietary supplement: Lactobacillus rhamnosus F-1、Lactobacillus reuteri GL-104; Dietary supplement: Placebo

• Study Type: Interventional
• Enrollment (Actual): 225
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Taiwan
  • Taichung, Taiwan, 404
    • China Medical University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

1. Inclusion criteria:

   1. Age between 6 and 65 years.
   2. Diagnosed with allergic rhinitis by a qualified physician.
   3. Score ≥ 7 on the Score for Allergic Rhinitis (SFAR).
   4. Willing to participate and has signed the informed consent form.

2. Exclusion criteria:

   1. History of drug allergy or use of medications with high sensitivity or contraindications (e.g., allergy to antibiotics or antipyretics).
   2. Patients with rhinitis symptoms caused by structural abnormalities such as a deviated nasal septum.
   3. Patients receiving oral corticosteroid therapy.
   4. Consumption of probiotic-related products within the past 1 month (including drops, tablets, capsules, powders, yogurt, or fermented milk containing live bacteria).
   5. Participation in other clinical studies within the past 1 month.
   6. Receipt of immunotherapy within the past 1 year.
   7. Presence of major illnesses (e.g., possession of a catastrophic illness certificate) or severe immune, hematological, or congenital disorders.
   8. Deemed unsuitable for participation by a physician.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo	Dietary supplement: Placebo; Subjects take two capsules daily.
Experimental: Lactobacillus rhamnosus F-1	Dietary supplement: Lactobacillus rhamnosus F-1; Take one packet of probiotics (Lactobacillus rhamnosus F-1) twice daily.
Experimental: Lactobacillus rhamnosus F-1、Lactobacillus reuteri GL-104	Dietary supplement: Lactobacillus rhamnosus F-1、Lactobacillus reuteri GL-104; Take one packet of probiotics (Lactobacillus rhamnosus F-1、Lactobacillus reuteri GL-104) twice daily.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in Score for Allergic Rhinitis(SFAR)	The score ranges from 0 to 16 and includes 8 items. A higher score indicates a more severe severity.	Baseline (pre-intervention).
Changes in blood biochemical inflammatory markers.	Changes in the levels of IgE, ECP, CBC, IL-4, IL-10, IL-12, IFN-γ, TGF-β, Vitamin D3, IL-17, and TNF-α.	Baseline (pre-intervention), after 12 weeks of probiotic supplementation。
Analysis of gut microbiota composition	Changes in gut microbiota ratios were assessed using NGS before and after the intervention.	Baseline (pre-intervention) and after 12 weeks of probiotic supplementation.
Changes in the Score for Allergic Rhinitis and Rhinoconjunctivitis Quality of Life Questionnaire（RQLQ）	It includes 28 items across 7 areas (activity, sleep, non-nasal/eye symptoms, practical problems, nasal symptoms, eye symptoms, and emotions). Using a 7-point scale (0 = no trouble, 6 = extreme trouble), the lower the score, the better the quality of life.	Baseline (pre-intervention), after 12 weeks of probiotic supplementation, and 8 weeks after discontinuation.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in Visual Analogue Scale(VAS) scores	The higher the number from 1 to 10, the more uncomfortable it feels.	Baseline (pre-intervention), after 12 weeks of probiotic supplementation, and 8 weeks after discontinuation.
Changes in Total nasal symptoms score (TNSS).	It typically sums scores for four symptoms-nasal congestion, rhinorrhea (runny nose), nasal itching, and sneezing-each rated 0-3, resulting in a maximum total score of 12.A lower score indicates better control or improvement of nasal symptoms.	Baseline (pre-intervention), after 12 weeks of probiotic supplementation, and 8 weeks after discontinuation.
Changes in Rhinitis Control Assessment Test (RCAT) scores	The questionnaire contains 6 items, with a total score range of 6-30 points. The lower the score, the worse the rhinitis control is usually.	Baseline (pre-intervention), after 12 weeks of probiotic supplementation, and 8 weeks after discontinuation.

Collaborators and Investigators

• Sponsor: Glac Biotech Co., Ltd

Study record dates

Study Major Dates

• Study Start (Actual): February 26, 2024
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: April 2, 2026
• First Submitted That Met QC Criteria: April 9, 2026
• First Posted (Actual): April 16, 2026

Study Record Updates

• Last Update Posted (Actual): April 16, 2026
• Last Update Submitted That Met QC Criteria: April 9, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Probiotics; Allergic Diseases; Allergic rhinitis; Intestinal Flora
• Additional Relevant MeSH Terms: Immune System Diseases; Respiratory Tract Diseases; Respiratory Hypersensitivity; Hypersensitivity, Immediate; Hypersensitivity; Nose Diseases; Otorhinolaryngologic Diseases; Rhinitis; Rhinitis, Allergic
• Other Study ID Numbers: CMUH112-REC1-161

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No