Causes & Treatment

How does the Covid vaccine affect your period? The facts

Poppy Millar-Maher  |   10 Feb 2023

If you ran into any unusual PMS symptoms following your vaccination, you’re not alone. So what exactly is the covid vaccine and menstrual cycle link, why does it happen, and is it permanent?

As we continue to settle into a (relatively) post-Covid world, we’re still learning how vaccines can impact us in the long term. While most of us remember having an aching arm or feeling a bit flu-y after a jab, lots of women have also noticed a change to their periods.

A recent international study sampling nearly 20,000 women confirmed a connection between the vaccine and menstrual cycle length, so the impact is real, and it’s significant. 

This study relied on data gathered from Natural Cycles, an app which helps women track their fertility throughout the month, and we love it. Whether you’re trying to conceive, or you’d just like to keep an eye on your cycle, the app gives you a tailored tool for tracking your body’s natural flow each month. Try it out today – The Ribbon Box readers get 20% off with code TRB20.

While this is a breakthrough study, it’s still quite early to be drawing conclusions about the myriad effects of the vaccine. However, anything that impacts our cycles is important, so we’ve done a bit of research to give you the big picture, as far as we can.

How does the Covid jab affect your periods?

Covid-vaccinated women have mainly been reporting periods that are longer, heavier, delayed, or all of the above. So what’s the science behind this? Well, the first thing worth noting is that this isn’t unique to the Covid jab – other vaccines have been known to do the same for a short period of time.

How do vaccines work? (a quick Biology recap):

  • Viruses are transmitted in pathogens, which are disease-causing microbes
  • A vaccine introduces an inactive version of these pathogens
  • The vaccine triggers an immune response by mimicking a viral infection
  • White blood cells attack the pathogens and break them down
  • The body develops an immunity to the active version of the pathogens

How do vaccines affect hormones?

The Covid jab is, like any vaccine, a controlled attack on the immune system. We know that there’s a correlation between our immune system and hormones, so it makes sense for there to be some trickle-down effects on your body that you might not expect.

Part of the role of sex hormones is to control your period. Changes in these hormones can impact how and when you bleed. There are also immune cells in your uterine lining, and there is some chance that these can be affected by an event like a vaccination or a general illness.

How long will my periods be affected?

Fertility warriors among us may find a disrupted cycle troubling, but as far as we know there are no long-term concerns. If your periods are affected by the vaccine, they should return to normal shortly.

Exactly how long varies from woman to woman, but generally you can expect your cycle to return to normal after one or two cycles, which for most of us means around one to two months.

Covid vaccine menstrual cycle heavy long periods

Can the Covid jab affect fertility?

Here at The Ribbon Box we’re always keen to ask the question: what does this mean for my fertility? After all, in other instances changes to our periods could mean problems with fertility later down the line.

However, leading immunologist Viki Male, who has studied the effects of the vaccine on periods,  concluded that the covid vaccine has no impact on fertility, so those of us hoping to conceive can safely have the jab.

As the world continues to learn more about the fall-out of Covid and the side effects of the vaccine, we’ll keep an eye out for news with implications for fertility.

The Covid vaccine and your period – the wrap-up

To summarise – while for some of us the vaccine may well have a noticeable effect on our menstrual cycle, current reporting suggests changes will be temporary, with no lasting impact on our health or long-term fertility.

The Ribbon Box team are committed to giving you the facts on the latest health news, and we’re always keen to get your input.

Have you experienced changes to your periods after a Covid jab? Follow us @theribbonbox.fertility or join our squad to bring this important topic – and the conversation – up-to-speed.

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