Why do my breasts hurt before my period?

Because oestrogen and progesterone both rise through the second half of your cycle, then fall together in the days before bleeding starts, and both hormones act directly on breast tissue along the way. Oestrogen stimulates the milk ducts to grow; progesterone acts on the surrounding glandular tissue and causes it to hold onto fluid. Together they are what shows up as soreness, heaviness, aching or swelling in the run-up to your period. This is called cyclical breast pain, or cyclical mastalgia, and it is the most common type of breast pain there is.

What's actually happening:

• The rise happens after ovulation, and peaks right before your period. Oestrogen and progesterone are both higher in the luteal phase, the second half of your cycle, than in the first. The closer you get to bleeding, the more fluid and glandular swelling has had time to build up, which is why the soreness is usually worst in the final few days beforehand.
• It eases once your period starts. As both hormones fall and your period begins, the fluid retention resolves and the tenderness typically lifts within a few days.
• It is usually on both sides. Mayo Clinic notes that cyclical breast pain typically affects both breasts rather than one, and can spread up into the armpit; pain confined to a single spot in one breast is a different pattern, covered below.
• It is genuinely common. A StatPearls review puts lifetime prevalence of breast pain at up to seven in ten women, and cyclical pain tied to the menstrual cycle is the largest share of that.

The same hormonal window drives more than your breasts. The exhaustion many women feel before their period follows a related schedule, as do the headaches some get in the same window, the breakouts driven by the same hormone shift, and the mood swings that often show up alongside them.

Breast pain alone is not usually a sign of breast cancer, and having it does not raise your risk of a cancer diagnosis: the NHS notes pain by itself is rarely a cancer symptom, and StatPearls puts the share of women with breast pain who turn out to have breast cancer at only 2 to 7 percent. Still, a few changes are worth having looked at rather than assumed, per ACOG and the NHS:

• a lump or an area of new lumpiness that does not come and go with your cycle
• nipple discharge that is blood-stained, or that happens without squeezing
• a change in the shape, size or contour of the breast or nipple, or dimpling of the skin
• redness, warmth or swelling that suggests inflammation rather than ordinary tenderness
• pain confined to one specific spot in one breast, rather than a diffuse ache across both
• pain that does not ease within a few days of your period starting, or that has not settled after three to six months of tracking it

None of that is something to work out from a search; it is exactly what a clinician examines directly rather than you guessing from a description.

What helps in the ordinary sense: a well-fitted, supportive bra, including overnight if the soreness is bad enough to disturb your sleep, and cutting back on caffeine in the days it tends to flare, though the evidence for caffeine specifically is mixed rather than settled. What is worth handing a doctor, if it comes to that, is whether the pain actually tracks your cycle or turns up regardless of where you are in it, since that single distinction is what separates the ordinary pattern above from one worth investigating further. A period tracker built with a Muslim woman's actual cycle in mind, one that logs a symptom against the day you're on rather than just a date, is what turns that into a record you can actually show someone.