There are different theories about what causes PMS/PMDD pain, but underlying them all are hormones and our individual sensitivity to them.
Hormones: The main cause of PMS/PMDD pain is thought to be fluctuations in hormone levels during the luteal phase, especially a drop in oestrogen. Oestrogen protects against feelings of pain, so when levels are low, our perception of pain may be higher.
Prostaglandins: a decrease in progesterone during the late luteal phase triggers an increase in prostaglandins, which are involved in the inflammatory response. Prostaglandins can directly stimulate pain-sensing nerve endings, called nociceptors, leading to increased pain perception. By sensitising these nerve endings, we lower the pain threshold, causing even minor stimulation to trigger pain/a pain response.
Serotonin: sometimes called the ‘happy hormone,’ serotonin is a neurotransmitter which helps regulate mood, sleep, and pain perception. Oestrogen increases serotonin production and the number of serotonin receptors in the brain. This means that when oestrogen is low (aka during the luteal phase), we produce less serotonin and there are fewer receptors that can be activated. This makes us more sensitive to pain.
Fluid retention: experienced during PMS/PMDD may increase pressure in the head and cause headaches. It can also lead to bloating and swelling, which can put pressure on joints and muscles, causing discomfort. Fluid retention may result in breast swelling and increased sensitivity, causing breast tissue to feel tender, heavy, or painful.
Stress: emotional stress and tension can exacerbate PMS and PMDD symptoms, including headaches and migraines.
Diet: certain foods and drinks can trigger headaches in some individuals, and these sensitivities may be heightened during the luteal phase. Common triggers include alcohol, caffeine, chocolate, aged cheeses, and processed foods containing additives like monosodium glutamate (MSG).