Vitamin B6, including its form pyridoxamine HCl, has been studied as a supplement for managing symptoms of premenstrual syndrome (PMS), including PMS Type H (hyperhydration, characterized by bloating and water retention). The rationale for its use is based on the vitamin's role in neurotransmitter synthesis (such as serotonin and dopamine) and its involvement in hormonal regulation, which may influence mood and fluid balance. Several clinical trials from the 1980s and 1990s reported that vitamin B6 supplementation at doses typically ranging from 50 to 100 mg per day could lead to modest improvements in overall PMS symptoms compared to placebo. However, these studies often had methodological limitations, such as small sample sizes, inconsistent diagnostic criteria for PMS, and variable outcome measures.

Specifically regarding PMS Type H, the direct evidence for vitamin B6 reducing bloating or water retention is limited and not robust. Most clinical research has assessed overall PMS symptom scores or focused on affective symptoms (mood, irritability) rather than physical symptoms like fluid retention. Systematic reviews and guidelines (such as those from the Royal College of Obstetricians and Gynaecologists) note that while vitamin B6 may offer some benefit for PMS in general, evidence for its specific effect on hyperhydration symptoms is insufficient. Safety concerns also arise at doses higher than 100 mg/day due to the risk of peripheral neuropathy.

In summary, there is some scientific basis for vitamin B6 use in PMS overall, but the evidence specifically for PMS Type H (bloating/water retention) is weak and rated as low quality.