Cramp Bark (Viburnum opulus) has a long history of traditional use for relieving muscle cramps and spasms, particularly menstrual cramps and uterine spasms. Native American and European herbalists have used the bark as an antispasmodic remedy for centuries, often recommending it for dysmenorrhea (painful menstruation), muscle tension, and sometimes for gastrointestinal or skeletal muscle cramps.

The traditional rationale is based on observed effects and passed-down herbal knowledge rather than on rigorous scientific research. Some historical texts describe preparation methods and dosages, and Cramp Bark is included in various traditional pharmacopeias and herbal formularies.

Scientifically, there are a few in vitro and animal studies suggesting that extracts from Cramp Bark may have muscle-relaxant and spasmolytic effects, possibly due to its content of valerianic acid, coumarins, and other phytochemicals. However, clinical trials in humans are lacking or very limited, and the evidence does not yet meet modern standards for scientific validation. Therefore, while supported by robust tradition and some preliminary laboratory findings, its use for cramps and spasms is not strongly validated by high-quality clinical research.