Astra Zeneca and Periods: Hi, I’m... - Women's Health

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Astra Zeneca and Periods

Knic profile image


I’m wondering if anyone who has received the AZ jab, is also experiencing longer cycles/late periods?

I’m 35 and had my AZ jab back in March, since then I’ve only had 1 period - that cycle was 54 days and now I’m currently on day 51 of this cycle and still no period.

I am waiting for a gynaecologist referral, but was just wondering if anyone has experienced this too?

4 Replies

I’ve heard of a lot of menstruation related issues that people were relating to having AZ vaccine, there was an segment on Woman’s Hour about it Personally I had the AZ vaccine back in March, and that month my period started a week early which I have put down to the vaccine, I can see no other reason why this should happen, my periods are regular and have been for years and in that time I’ve never been more than 1 day late/early. I reported it via the yellow card scheme.

The jabs are interfering with women's periods, but it's tending to make them start earlier and/or be heavier. I'm not sure if many have found they make the cycle longer though, so it would be a good idea to run it past your doctor.

I am having all sorts of cycle problems since having both jabs. Last month my period was 10 days late, this month it was 8 days early! And I have been ovulating all over the place. I hadn't realised it could be down to the jab, thats reassuring as I thought I was menopausal!

wobblybee profile image

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OK, but what could be going on here?

Experts say it's really hard to know for sure. For those women who report more pain than usual, "it may be that aches and pains post-vaccine compound normal menstrual pains," infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security in Maryland, tells Health.

The heavier flow is a little trickier to explain. A small study of 233 women of childbearing age with clinically diagnosed COVID-19 reported some menstrual changes. Of the 177 patients with records about their periods, 25% had "menstrual volume changes," 20% had a lighter-than-usual period, and 19% had a longer-than-usual cycle, according to the study, which was published in January in the journal Reproductive BioMedicine Online. While it's possible that the COVID-19 vaccine could have a similar effect, it's not known at this time.

There's also the possibility that stress could play a role. Stress can be an annoying and somewhat vague excuse for period-related changes, but it's a real possibility, Gloria A. Bachmann, MD, associate dean for women's health at the Rutgers Robert Wood Johnson Medical School in New Jersey, tells Health. "Menstrual cycles can be altered or influenced by many factors, including stress, poor sleep, exercise, and some medications," she says. "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."

The idea that a vaccine might affect a woman's cycle is a tough one to explain from a biological standpoint, though, Mark Turrentine, MD, professor of obstetrics and gynecology at Baylor College of Medicine in Texas, tells Health. "There is no biologic mechanism that would account for [the] disruption of the menstrual cycle following receipt of the COVID-19 vaccine," he says. Dr. Turrentine also points out that unusual vaginal bleeding "was not a side effect reported in any of the clinical trials from the vaccine manufacturers," adding, "no large-scale adverse events regarding irregular menstrual bleeding have been noted to date."

Despite the personal stories from women online, women's health expert Jennifer Wider, MD, tells Health that there just isn't enough data to show that the vaccine could impact menstrual cycles. "Could the vaccine interact with the body's hormones or are there other factors at play like stress? That remains to be seen," she says.

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