“I got the Moderna on the last day of my period. Nine (!!!!) days later another period appeared and has been a nightmare,” another commented.
“So many people felt very alone in this experience because it wasn’t on the list of possible side effects,” Lee said. “They thought something was wrong with them, that something more severe could be wrong, and for a number of folks who did try to report it to somebody they were dismissed.”
Experts told Health.com it’s difficult to say why this is happening.
“Menstrual cycles can be altered or influenced by many factors, including stress, poor sleep, exercise, and some medications,” said Dr. Gloria A. Bachmann, associate dean for women’s health at the Rutgers Robert Wood Johnson Medical School in New Jersey. “Therefore, it wouldn’t be that unusual for some women to notice, after receiving the vaccination, changes in their period, such as it coming on earlier, or having a heavier flow, or noticing more cramping than they usually have.”
Clancy tweeted that her period after the second shot “wasn’t nearly as bad as after the first shot,” and she thinks it will soon “be back to what’s typical for me.” She added that she and Lee plan to study this further.