Some people avoid using SSRIs as they feel they "do not target the hormones which cause PMDD", however SSRIs may work differently in the treatment of PMDD than in the treatment of other diagnoses like major depressive disorder. Usually, SSRIs affect the function of serotonin, a neurotransmitter.

However, in PMDD, SSRIs may be influencing hormones, such as allopregnanolone (ALLO), which is a derivative of progesterone. Scientists think that SSRIs may work in PMDD by altering ALLO levels in the brain, although this has not been fully tested.

SSRI effects in PMDD may also be due in part to the improvement of serotonin function.

- Dr Liisa Hantsoo. IAPMD Clinical Advisory Board.