MSM / Methylsulfonylmethane for Allergic Rhinitis
MSM (methylsulfonylmethane) is not proven to relieve allergic rhinitis. The only human data come from two small, low-quality trials, so any benefit remains unconfirmed and MSM should not replace established hay-fever treatments.
Why this grade7-layer evidence engine
This claim earns a Weak (Tier C) grade because the entire human evidence base is just two small, methodologically weak trials. Barrager 2002 (PMID 12006124) was an open-label study of 50 people with no placebo group, so its reported symptom improvements cannot be separated from natural seasonal swings or placebo effect; notably, IgE and histamine did not change, leaving any mechanism unclear. A published commentary (PMID 12165181) further flagged its lack of pollen-count tracking and questionnaire standardization.
The second trial, Hewlings 2018 (PMID 30497995), was double-blind but explicitly exploratory, with only 18 completers. It reported reduced nasal symptom scores and improved nasal airflow at certain doses, but a sample this small is far too underpowered to be conclusive. No placebo-controlled trial of adequate size, and no systematic review or meta-analysis, exists for this question, and no new trials have appeared since.
Regulators and clinicians do not endorse MSM for allergies. The US FDA recognizes MSM only as generally safe for food use, which speaks to safety, not effectiveness. The EU's EFSA rejected MSM-related health claims, and major bodies (NIH/NCCIH, Mayo Clinic, and AAAAI/ACAAI allergy guidelines) do not address or recommend it for allergic rhinitis. Proven options such as intranasal corticosteroids and antihistamines remain the standard of care.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.47
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 無高階證據可裁決
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status