Background: Herbal supplements are classified as foods rather than drugs and are not required to undergo premarketing review by the Food and Drug Administration. Yohimbine is an alpha(2)-antagonist available in both prescription and herbal supplement products.
Objective: To determine the prevalence and severity of yohimbine-related adverse drug events (ADEs) reported to the California Poison Control System (CPCS).
Methods: A retrospective review of the CPCS electronic database of cases within a 7-year period (2000-2006) was conducted. Cases involving adults aged 18 and older who were symptomatic following exposure to a yohimbine-containing product, with a causality rating of possible or better on the Naranjo scale, were included.
Results: A total of 238 cases were identified. There was a substantial increase in the annual prevalence of yohimbine-associated ADEs reported to the CPCS between 2000 and 2006; specifically, the prevalence (per 10,000 total adult exposures) increased from 1.8 cases in 2000 to 8.0 cases in 2006). The majority (98.7%) of cases involved herbal (vs prescription) yohimbine products. Common reasons for use included sexual enhancement (27.7%), weight loss (9.2%), and stimulant effects (7.6%). Common ADEs reported included: gastrointestinal distress (46%), tachycardia (43%), anxiety/agitation (33%), and hypertension (25%). Yohimbine exposures were associated with a significantly greater proportion of severe outcomes and were more likely to require management at a health-care facility than the average substance exposure reported to the CPCS (odds ratios [95% CIs] were 5.81 [4.43 to 7.64] and 2.35 [1.82 to 3.04], respectively).
Conclusions: A substantial increase in the prevalence of ADEs associated with yohimbine herbal products was seen between 2000 and 2006. These ADEs were associated with significantly more serious outcomes than the average exposures reported to the CPCS. A reexamination of whether yohimbine should be considered a "safe" dietary supplement under the Dietary Supplement Health and Education Act is warranted.