Acute diarrhea (AD) is an important cause of morbidity and mortality among both children and adults. An ideal antidiarrheal treatment should be safe, effective, compatible with Oral Rehydration Solution, and inexpensive. Herbal medicines, if effective, should fit these criteria as well or better than standard treatment. The objective of the present study was to assess the effectiveness of plant preparations in patients with AD in reports of randomized and non-randomized controlled trials. The aims of the present study were to identify effective antidiarrheal herbs and to identify potential antidiarrheal herbs for future studies of efficacy through well designed clinical trials in human populations. Nineteen published studies of herbal management of AD were examined to identify effective plant preparations. Ten plant preparations including Berberine (Berberis aristata, Berberidaceae), tormentil root (Potentilla tormentilla, Rosaceae), baobaosan (from the baohuahua herb), carob (Ceratonia siliqua, Fabaceae), pectin (Malus domestica, Rosaceae), wood creosote (Creosote bush, Zygophyllaceae), guava (Psidium guajava L., Myrtaceae), belladonna (Atropa belladonna, Solanaceae), white bean (Phaseolis vulgaris, Fabaceae), and wheat (Triticum aestivum, Poaceae) were identified. Qualitative data analysis of nineteen clinical trials indicated berberines potentially valuable antisecretory effects against diarrhea caused by Vibrio cholerae and enterotoxigenic Escherichia coli. Tormentil root showed significant efficacy against rotavirus-induced diarrhea; carob exhibited antidiarrheal properties not only by acting to detoxify and constipate but by providing a rich source of calories. Guava and belladonna are antispasmodics and have been shown to relieve the symptoms of AD. Future randomized controlled trials are needed to evaluate their efficacy and safety.