Safety and efficacy of a traditional herbal medicine (Throat Coat) in symptomatic temporary relief of pain in patients with acute pharyngitis: a multicenter, prospective, randomized, double-blinded, placebo-controlled study

J Altern Complement Med. 2003 Apr;9(2):285-98. doi: 10.1089/10755530360623400.


Objective: To investigate the safety and efficacy of Throat Coat) (Traditional Medicinals,) Sebastopol, CA), a traditional demulcent herbal tea, in comparison with a placebo tea in the symptomatic treatment of acute pharyngitis.

Design: Multicenter, prospective, randomized, double-blinded, placebo-controlled, two-armed, parallel-group clinical trial.

Settings: Three primary care clinics in Duluth, MN, Madison, WI, and Middleton, WI.

Subjects: Patients of both genders (>or=18 years of age) with clinical diagnoses of acute pharyngitis.

Interventions: Patients (n = 60) were randomly assigned to receive 5-8 oz of Throat Coat (n = 30) or a placebo (n = 30), four to six times daily. The study period was 2 to 7 days with a window for the follow-up visit of 2-10 days accounting for the variable duration of sore throat symptoms.

Outcome measures: Primary efficacy parameter: sum of pain intensity differences (SPID) for pain in throat on swallowing, calculated as the area under the curve (AUC) of pain intensity difference scores (assessed at 1 minute, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 30 minutes after treatment). Secondary efficacy parameter: total pain relief (TOTPAR), calculated as the AUC from time 0 (baseline) to 30 minutes of pain relief (assessed at 1 minute, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 30 minutes).

Results: Compared to placebo, intensity of throat pain when swallowing was significantly reduced by Throat Coat in intention to treat and valid for efficacy analysis (VEA). Significant differences in change from baseline pain were observed at 5 min (p = 0.007), 10 min (p = 0.005), 15 minutes (p = 0.01), 20 minutes (p = 0.05), and 30 minutes (p = 0.04) after completion of the first dose (VEA analysis). There was a statistically significant improvement of SPID in the Throat Coat-treated group: Least square means +/- standard error of the means (SEM) of SPID were -16.5 +/- 13.9 in the placebo group and -43.8 +/- 11.9 in the Throat Coat-treated group (p = 0.012). TOTPAR was also significantly higher in the Throat Coat-treated group: Least square means +/- SEM of TOTPAR were 32.4 +/- 12.8 in the placebo group and 53.6 +/- 10.9 in the Throat Coat-treated group (p = 0.031). This study shows that Throat Coat is significantly superior to placebo and provided a rapid, temporary relief of sore throat pain in patients with pharyngitis.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Administration, Oral
  • Adult
  • Analgesics / administration & dosage*
  • Area Under Curve
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Pain Measurement / drug effects
  • Patient Satisfaction
  • Pharyngitis / drug therapy*
  • Phytotherapy*
  • Plant Extracts / administration & dosage*
  • Plants, Medicinal*
  • Prospective Studies
  • Surveys and Questionnaires
  • Time Factors
  • Treatment Outcome
  • United States


  • Analgesics
  • Plant Extracts