Written by Alice Sholl
24th Mar 2022 • 4 minute read
Dr Nadja Auerbach
Reviewed by
Dr Nadja Auerbach, MBBS BSc Dip IBLM/BSLM

Irregular periods are common among people who have menstrual cycles — there are lots of reasons you might have them. They’re often nothing to worry about, but it’s important to know when to investigate further.

What’s an irregular period?

You have irregular periods if the gap between them keeps changing. 

Typically, this gap is between 25 and 30 days. But they can be longer or shorter than this — menstrual cycle lengths differ from person to person.

If your period is irregular, you might find it comes sooner than expected in some months, and later in others.

Are irregular periods normal?

Irregular periods are extremely common — they affect around a third of people who have periods. But it’s important you figure out why your periods are irregular.

Irregular periods don’t always mean you have a health problem. But if you’re worried about your menstrual cycle, it’s a good idea to speak to your GP. 

If you don’t have a period for 3 to 6 months and aren’t pregnant, you should speak to your doctor.

What causes irregular periods?

Lots of things can cause irregular periods, like a change in your routine or medication. 

Sometimes, irregular periods happen after coming off the contraceptive pill. They can also be a sign of a hormonal imbalance or polycystic ovary syndrome (PCOS). You can check your hormones as part of a PCOS blood test.

If your periods become heavier than usual, you’re bleeding after sex, or you’re bleeding between periods, it’s important to speak to your GP. That’s because these can sometimes be a sign of a more serious health condition — like womb or cervical cancer. So it’s important to rule out this possibility.

Lifestyle factors, like exercise, weight, and stress are connected to irregular periods too. Find out more about stress and how to manage it.

Irregular periods after stopping taking the combined pill

Your periods might be irregular or not return for a while after you stop taking the combined pill. They usually go back to normal within a few months, but this can vary from person to person.

It’s unlikely the combined pill will cause fertility or period problems. But taking it can hide period problems you had before.

If they haven’t gone back to normal after 6 months, you might want to speak to your GP to investigate further.

Irregular periods after pregnancy

After pregnancy, certain aspects of your period might be different — like their regularity and heaviness.

You’re more likely to have irregular periods if your period comes back when you’re still breastfeeding.

It might take a few months for them to go back to normal. If you’re worried about your period after pregnancy, it’s a good idea to talk to your GP.

What if your periods stop altogether?

Missing one or more periods is called amenorrhea. 

Certain health changes can cause amenorrhea, including:

If you think you might be pregnant or have a health condition, see a GP.

Life circumstances can make your period stop too, including: 

  • sudden weight loss
  • doing too much exercise
  • stress
  • carrying excess weight

If your periods have stopped because you aren’t eating enough food or are exercising a lot, your GP might ask you to change the amount you’re eating and exercising. If you’re an athlete, they might refer you to a dietician.

Is there treatment for irregular periods?

Treatment for irregular periods depends on what’s causing them. So it’s important to figure out why you are having irregular periods first.

If you’ve recently been pregnant or stopped taking the contraceptive pill, your periods should come back on their own.

If you think you could have PCOS, you should speak to your GP — they might want to investigate this further. They can suggest lifestyle changes that might help manage your symptoms.

Stress can affect the hormones produced by your brain. These then go on to affect hormones released from your ovaries. This can cause irregular or missed periods. 

If you think stress is causing irregular periods, there are some things you can do at home to help, including:

  • regular exercise — aim for 150 minutes of moderate activity, or 75 minutes of vigorous activity a week
  • get enough sleep — try to get at least 7 hours every night
  • eat a diet full of fruit, vegetables, oily fish, nuts and seeds, and whole grains — like a Mediterranean diet 
  • connect with family and friends — having social support can help lower levels of a stress hormone called cortisol