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Randomized Controlled Trial
. 2016 Dec 15;23(14):1735-1742.
doi: 10.1016/j.phymed.2016.10.012. Epub 2016 Oct 24.

Long-term Chamomile (Matricaria Chamomilla L.) Treatment for Generalized Anxiety Disorder: A Randomized Clinical Trial

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Free PMC article
Randomized Controlled Trial

Long-term Chamomile (Matricaria Chamomilla L.) Treatment for Generalized Anxiety Disorder: A Randomized Clinical Trial

Jun J Mao et al. Phytomedicine. .
Free PMC article

Abstract

Background: Generalized Anxiety Disorder (GAD) is one of the most common anxiety disorders treated in primary care, yet current therapies have limited efficacy and substantial side effects.

Purpose: To evaluate long-term chamomile (Matricaria chamomilla L.) use for prevention of GAD symptom relapse.

Methods: Outpatients from primary care practices and local communities with a primary diagnosis of moderate-to-severe GAD were enrolled for this two-phase study at a large US academic medical center. During Phase 1, eligible participants received 12 weeks of open-label therapy with chamomile pharmaceutical grade extract 1500mg (500mg capsule 3 times daily). During Phase 2, treatment responders were randomized to either 26 weeks of continuation chamomile therapy or placebo in a double-blinded, placebo-substitution design. The primary outcome was time to relapse during continuation therapy, analyzed using Cox proportional hazards. Secondary outcomes included the proportion who relapsed, treatment-emergent adverse events, and vital sign changes. This study is registered at ClinicalTrials.gov, identifier NCT01072344.

Results: Between March 1, 2010, and June 30, 2015, we enrolled 179 participants. Of those, 93 (51.9%) were responders and agreed to continue in the double-blind randomized controlled trial. A numerically greater number of placebo-switched (n=12/47; 25.5%) versus chamomile-continuation (n = 7/46; 15.2%) participants relapsed during follow-up. Mean time to relapse was 11.4 ± 8.4 weeks for chamomile and 6.3 ± 3.9 weeks for placebo. Hazard of relapse was non-significantly lower for chamomile (hazard ratio, 0.52; 95% CI, 0.20-1.33; P = 0.16). During follow-up, chamomile participants maintained significantly lower GAD symptoms than placebo (P = 0.0032), with significant reductions in body weight (P = 0.046) and mean arterial blood pressure (P = 0.0063). Both treatments had similar low adverse event rates.

Conclusions: Long-term chamomile was safe and significantly reduced moderate-to-severe GAD symptoms, but did not significantly reduce rate of relapse. Our limited sample size and lower than expected rate of placebo group relapse likely contributed to the non-significant primary outcome finding. Possible chamomile superiority over placebo requires further examination in large-scale studies.

Keywords: Chamomile; Clinical trials; Generalized anxiety disorder; Herbal medicine.

Conflict of interest statement

Conflict of interest:

The authors declare that they have no conflict of interest.

Figures

Fig. 1
Fig. 1
Upper panel: HPLC fingerprint of the extract after alkaline hydrolysis. Lower panel: Overlay of the chromatograms of the hydrolyzed extract with the chromatogram of the reference standards, USP Apigenin-7-glucoside RS and of 7-methoxycoumarin.
Fig. 2
Fig. 2
Screening, Randomization, and Completion of 38-Week Evaluations
Fig. 3
Fig. 3
Time to Relapse of GAD Symptoms Between Chamomile and Placebo
Fig. 4
Fig. 4
Mean Weight Change by Treatment Groups
Fig. 5
Fig. 5
Mean Arterial Blood Pressure Change by Treatment Groups

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