Agnuside is an iridoid glycoside found in the fruit of Vitex agnus-castus (chaste tree). The use of Vitex agnus-castus for female reproductive health, including dysmenorrhea (painful menstruation), is well documented in traditional European and Mediterranean medicine. However, the specific evidence supporting agnuside itself for dysmenorrhea is limited. Most clinical studies focus on standardized extracts of the whole fruit rather than isolated agnuside.

Some randomized clinical trials and systematic reviews suggest that Vitex agnus-castus extracts may reduce symptoms of premenstrual syndrome (PMS) and, to a lesser extent, dysmenorrhea, likely due to dopaminergic effects that modulate prolactin and influence hormone balance. Agnuside is considered a marker compound for extract standardization and is thought to contribute to the pharmacological activity, but direct clinical evidence for agnuside alone in dysmenorrhea is lacking.

In summary, while there is limited scientific evidence supporting the use of Vitex agnus-castus (which contains agnuside) for dysmenorrhea, the specific efficacy of agnuside itself is not well established. The overall evidence is modest, justifying a low-to-moderate rating.