My period changed after the vaccine. Now what?

Image: Anthony Tran via Unsplash

So you’ve had the vaccine and your period has disappeared, come early or late or feels somehow different. Or maybe you feel like your body isn’t going through the hormonal shifts it usually does. Now what?

Maybe, you’re still on the fence and are confused about what to do because of all the chatter you’re hearing on social media and the internet. I am not here to add to that. Instead, I’m going to share with you the same advice I share with clients and friends who’ve asked the same question because the most important thing you’ll likely be interested in is getting your cycle back on track.

If your cycle has gone out of whack, you are definitely not alone and you absolutely should let your GP know. It’s acknowledged by now that cycle changes may well be a side effect of the vaccine (of which there are many, and the side effects vary from vaccine to vaccine). Long term effects are unknown because it’s just too early to tell. So many women feel disempowered when it comes to their periods and bodies anyway because they do not know enough about them. This is why tracking your cycle is paramount.

The best way to know definitively that the vaccine has affected your cycle, is to track it.

Tracking your cycle means knowing where you are in your cycle, and noting down your lived experience of it (physically, mentally, emotionally). It can (and I would recommend) involve tracking your basal body temperature to include ovulation tracking. The truth is, that without tracking your cycle, there is no way to know what is happening (or not) when, and whether the issues you’re worried about are vaccine related or were already there to start with. Let’s break this down:

How your cycle works (in easy lingo)

Your ovaries are where your eggs are stored. Each egg is housed in a follicle (like an eggshell). Hormones stimulate your ovaries to release one per cycle — this is ovulation. This egg is released and the follicle that held it begins to secrete progesterone — the hormone needed to support pregnancy. Progesterone helps the lining of the womb to thicken in case of pregnancy. The follicle (which is now called a corpus luteum) can only survive for so long, and the lining of the womb can only thicken to a certain point. If no pregnancy occurs, the follicle/corpus luteum dies and the womb lining will be shed, resulting in your period. The life span of the follicle is around 100 days. This is a very simplified explanation, and the most important things to take from it are this:

  1. Because your period is caused by the effects of what happens with the follicle after ovulation, it’s impossible to have one without ovulation. No ovulation = no period.
  2. The corpus luteum can only survive for a certain length of time, approximately 11–16 days (and the exact number will be specific to you)
  3. The hormones that stimulate the release of your eggs are all affected by many things including illness and immune system response, stress, toxins and nutrition
  4. It takes around 100 days from the desired egg being chosen to ovulation

Why tracking is so important

So many people tell me their cycles have changed for whatever reason, or their periods are suddenly late, early or irregular but they don’t track their cycles. And while you might be someone with a very regular cycle who can read your body very well, the truth is that without tracking your cycle, it’s guess work. You can have a 28 day cycle every month for years, but this doesn’t mean the next one will be.

It is impossible to predict your future cycles based on past ones

This is because as I just mentioned, your cycle is susceptible to influence from the outside world. Add onto that the first thing to remember from my menstrual cycle 101 above: Your period can only happen when you’ve ovulated. No ovulation, no period. Your body gives you clues as to when ovulation is likely to happen, but it’s an incredibly sensitive system and your body can have problems ovulating, or decide ovulation isn’t important at that moment in time.

Remember, whether you want a baby or not, your body will try to make one anyway. Pregnancy is an incredibly stressful event for the body, so if you’re experiencing any kind of stress, your body may decide that ovulation just isn’t important and it’s better to wait a while (unfortunately our body doesn’t understand the difference between the stress of constant Instagram notifications and the grief of losing a loved one).

Tracking your ovulation is as simple as taking your temperature in the morning. Once you’ve ovulated, your body temperature rises in a clear way. This means you’ll be able to confirm a very important part of your cycle — that you’ve ovulated. This takes out the guesswork and reliance on seeing fluid in your underwear/having ovulation cramps/feeling horny and make it very clear.

And remember, because that corpus luteum can only survive for so long, you’ll be able to say with certainty that your period will arrive 11–16 days after that (any longer than 18 warrants a pregnancy test). If your period comes consistently less than 11 days after ovulation, it can be a sign that you’re not producing enough progesterone, which can be helped along with supplements. This is usually seen in a shorter than usual cycle.

If you find that your temperature keeps rising and dropping back down again instead of staying high for 3+ days, it’s a sure sign that your body is under stress and ovulation isn’t taking place as it should. This is usually seen in a longer than usual cycle.

Once you know you’re ovulating, you can accurately predict your period.

If you’re concerned about your cycles having changed after the vaccine, tracking your ovulation will help you to know that hormonally, things are working as they should. This is also something that will massively help your GP/gynae too.

Give yourself 100 days

As mentioned, the lifecycle of that corpus luteum is 100 days — a little over three months. I know we tend to want things to happen overnight, but give yourself a minimum of 3 months when it comes to your cycle, whether it’s monitoring post-vaccine, preparing for pregnancy or trying new supplements. This is also why I don’t work with anyone for less than 3 months — it’s simply not realistic to expect results so quickly. Commit to tracking your cycle, and supporting your body with balanced nutrition, plenty of hydration and exercise/movement — the usual suspects. If after three cycles, things are still unsettled, go back to your doctor. Plus, going with a filled out app/tracker will put you in good stead and help the process along.

Support your body

You know now that your cycle can be affected by outside factors. The vaccine is one of them, as is is illness. Your immune system is an amazing thing and, remember, if your body is fighting off an infection (and this happens as part of vaccinations), ovulation will not be deemed important — why get pregnant when you’re sick? What’s important, is to help ovulation occur, for your cycle to work optimally and to assist your liver in flushing out excess toxins. I can highly recommend pretty much everything from Clara Bailey when it comes to finding out about cyclical health, including which diet is best, herbs and supplements. Don’t underestimate the power you have to help yourself.

  • Eat a balanced, healthy diet with as little processed foods as possible (we want to avoid any extra toxins for the liver to deal with)
  • Get regular, good quality sleep (your hormones are affected by your sleep! Prioritise it instead of squeezing it in)
  • Reduce toxins wherever you can in your life. Opt for organic food, natural cosmetics and avoid alcohol/coffee where possible
  • Prioritises your self-care, whatever that means to you. Bubble baths, dog walks, listening to music — whatever helps you to destress will help your nervous system and cycle

And finally…

Don’t panic. Avoid reading certain Reddit threads, unfollow certain people from social media. Consuming things that make you anxious is another way of adding stress to your body and remember, your body is an amazing, capable thing. It knows how to heal itself, once we get out the way.

This article was first published at on October 22, 2021




Natalie K. Martin is a Menstrual Cycle Coach guiding women and menstruators swap PMS for power, and trade period struggle for bliss.

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Natalie K. Martin

Natalie K. Martin

Natalie K. Martin is a Menstrual Cycle Coach guiding women and menstruators swap PMS for power, and trade period struggle for bliss.

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