Pycnogenol, a standardized extract from French maritime pine bark, has been investigated for its potential to support or treat premenstrual syndrome (PMS). The scientific evidence for its use in PMS is limited but present. Several small randomized controlled trials (RCTs) have evaluated Pycnogenol for PMS symptom relief. For example, a study published in the "Journal of Reproductive Medicine" (2008) found that women taking 60 mg per day of Pycnogenol for two menstrual cycles reported statistically significant reductions in PMS symptoms compared to placebo. Another study in "International Journal of Gynaecology and Obstetrics" (2007) supported these findings, particularly for symptoms such as abdominal pain, fatigue, and mood swings.

The proposed mechanisms include Pycnogenol’s anti-inflammatory and antioxidant properties, as well as its possible effects on endothelial function and microcirculation, which may address some physical and psychological symptoms of PMS. However, the number of participants in these studies was small, and most trials were short in duration and sponsored by manufacturers. Systematic reviews and independent analyses have noted the potential, but emphasize that the quality of evidence is moderate to low due to methodological limitations and a lack of large-scale, independent RCTs.

In summary, while there is some scientific evidence supporting the use of Pycnogenol for PMS, it is not robust, and further, larger, independent studies are needed to draw definitive conclusions.