Allergy, Rhinitis, Allergic
Conditions
Keywords
ascorbic acid, skin prick test, vitamin C, antihistamine
Brief summary
This study will assess the effect of taking vitamin C on allergy skin test.
Detailed description
Allergic rhinitis (AR) is an Immunoglobulin E (IgE) mediated inflammation of the nasal cavity. House dust mite is the most common causative allergen. The skin prick test is the preferred method to confirm allergy. This test is interpreted by measuring the skin wheal reaction in response to allergen application and histamine. Prior studies have shown that Vitamin C may have antihistamine effect that may reduce the wheal reaction in skin prick test thus cause difficulties to interpret the results. Current guidelines do not recommend cessation of vitamin C prior to skin prick test. This will require further study in order to further understand the effect of vitamin C in commercially available dose on the skin prick test wheal reaction. In this randomized placebo controlled trial, consecutive participant visiting the ENT clinic with allergic rhinitis and prior positive skin prick test towards dust mite will be screened for inclusion and exclusion criteria. Participants will either receive vitamin C 1000mg daily for 7 days or placebo. The skin prick test will be performed after one week of intervention and the area of the wheal reaction area (mm2) and longest diameter (mm) recorded. This will be compared between the two groups. The expected outcome is that participants with oral supplementation of vitamin C will have reduced SPT wheal reaction compared to placebo group.
Interventions
DIETARY_SUPPLEMENTAscorbic acid 1000mg
Health supplement
OTHERPlacebo
Glucose chewable tablet without any ascorbic acid
Sponsors
National University of Malaysia
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
DIAGNOSTIC
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Masking description
Tablets will be despensed by a research assistant
Intervention model description
Participant assigned to only one intervention per arm either vitamin C or placebo tablets
Eligibility
Sex/Gender
ALL
Age
18 Years to 40 Years
Healthy volunteers
No
Inclusion criteria
* Participants above 18-years old * Participants with history at least 2 symptoms of rhinitis triggered by dust * Positive SPT to Dermatophagoides pteronyssinus with wheal reaction of at least 5 mm done within the past 1 year.
Exclusion criteria
* Prior skin prick test result form do not include a tracing of the wheal reaction. * Prior skin prick test was not performed in HCTM. * Participants who are actively smoking or who have smoked cigarette or vaped in the past 6 months * Participants with skin conditions affecting the volar aspects of the arm. * Participants on beta-blockers * Participants contraindicated for skin prick test (pregnancy, history of anaphylaxis, poorly controlled asthma) * Participants on long term supplements (multivitamin, traditional supplement) * Participants contraindicated for vitamin c (vitamin c allergy, kidney dysfunction, history of kidney or bladder stones, hyperuricemia, thalassemia, G6PD deficiency, sickle cell disease, hamatochromatosis) * Participants at risk of vitamin C deficiency (hyperthyroidism, elderly, beastfeeding, diarrhoea, restricted diet secondary to inflammatory bowel disease, anorexia or cancer)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Skin prick test wheal area of vitamin C group compared to placebo | Day 8 | Skin wheal reaction is measured using computer software. Day 8 wheal area of vitamin C group compared to placebo. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Skin prick test wheal reaction at day 8 of intevention compraed to prior skin prick test done as standard of care | Day 8 | Skin wheal reaction are is measured from prior skin test record (baseline) and at day 8 skin test repeated and measured. Area at day 7 - baseline. |
Countries
Malaysia
Contacts
Primary ContactAneeza K W Hamizan, MD
Outcome results
None listed