Synthroid and Menstrual period.

I can only say that being on Synthroid does affect your menstrual cycle. If you were having problems with your periods coming too frequently, it should straighten that out where they should come more normally (like 28-30 days), or if you were having extreme pms, or bad cramps, it should help with this also. I would say (not a doctor here), that it is affecting your period, but your body is probably adjusting to the medicine (there is an adjustment period). I would let your doctor know about it anyhow to be on the safe side. -Karly