The 5 days when nothing helps.
Or at least that's what you think.

The most studied ingredient for women with PCOS and irregular cycles. At 2000-4000 mg it has shown improved cycle regularity, insulin sensitivity and reduced androgen symptoms (Unfer et al., 2017). Involved in insulin signaling and FSH receptor pathways.

Chelated form with ~80% bioavailability, no stomach irritation. Magnesium reduces muscle cramps and water retention. Facchinetti (1991) showed significant improvement in PMS symptoms at 400 mg/day. Bisglycinate crosses the blood-brain barrier, it also helps with sleep.

The active form pyridoxal-5-phosphate. Involved in the synthesis of serotonin and GABA, the two neurotransmitters disrupted in PMS. Wyatt et al. (1999), a meta-analysis of 9 studies: B6 significantly reduces PMS symptoms vs. placebo.

An amino acid that acts as an inhibitory neurotransmitter — a biological "switch" for the nervous system. Helps the body cool down for deep sleep (Kawai et al., 2007). Critical for women whose sleep worsens in the days before their cycle, when progesterone drops.

Doesn't act directly on PMS. But stress raises cortisol, which suppresses progesterone. Salve (2019, 60 randomized participants): 600 mg a day for 60 days lowered cortisol by 27.9%. In Corti-Glow, 300 mg of ashwagandha per sachet, for long-term evening use in women. Less stress = milder PMS.