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What Is an Irregular Period? Identifying Different Symptoms of PCOS

PCOS Symptoms and Irregular Periods

You might be surprised to learn the average woman has 400 periods throughout her lifetime. According to the NHS, a typical monthly cycle is 28 days, with a period lasting around 5 days.i  However, this window can range from 21-40 days depending on individual hormone levels.ii

While these may not be the most exciting facts to have at your disposal, they serve a purpose, especially if you’ve been diagnosed with PCOS. This is because PCOS is known to affect ovulation. Therefore, it’s not uncommon to have a menstrual cycle that falls beyond these parameters. 

Experiencing irregular periods as a result of PCOS can be disconcerting and leave you chewing over many questions: what if my periods are irregular? What if I have abnormally light periods? And what if I don’t have periods at all?

Above all, it’s can be helpful to understand exactly what an irregular period is because irregularities manifest in different ways. With that in mind, this piece offers a breakdown of the most common period issues, the role PCOS plays in the equation, and helpful medical, lifestyle and behavioural strategies to mitigate them.

Light or infrequent periods (Oligomenorrhea)  

Oligomenorrhea occurs when your periods are more than 35 days apart and you have four to nine periods a year. This often happens if you’ve only recently started menstruating. Some young women don’t have a regular cycle for several years after their first period, which is considered normal and not usually a cause for concern.

If your cycle varies by a few days from one month to the next, again, it’s not generally considered irregular. Some women have a period every three weeks, others every five – either way, it’s nothing out of the ordinary unless you have periods that are fewer than three weeks or more than five weeks apart.

Frequent periods (Polymenorrhea)  

Having a period of fewer than 21 days apart is known as polymenorrhea. If you have polymenorrhea, your periods may also be irregular and/or unpredictable. It’s worth mentioning that polymenorrhea can affect your fertility since it means you ovulate sooner in your cycle than you should ordinarily.

Heavy periods (menorrhagia)  

During a normal period, a woman may lose around 30ml of blood. But if you have a heavy flow, it’s possible you may lose more. Losing more than 60ml of blood is classed as ‘menorrhagia’ – in other words, excessive bleeding. Heavy periods can also be excruciatingly painful (see dysmenorrhoea, below) and may last more than seven days.

To determine if you have heavy periods, consider how many tampons and/or pads you use daily. If you need an excessive amount of sanitary protection or bleed through clothes or bedding, you may have menorrhagia.

The NHS reports heavy periods aren’t anything too serious to worry about. However, it should come as no surprise that this can affect you emotionally and physically – not to mention disrupt your everyday life.

Abnormally light periods (Hypomenorrhoea)  

Unlike menorrhagia, hypomenorrhea denotes a very light flow and short periods. Taking the contraceptive pill or using another hormone-based method of contraception is known to cause abnormally light periods. Reassuringly, this isn’t purported to trigger fertility problems any more than having a normal cycle.

Absent periods (Amenorrhoea)  

There are two types of amenorrhoea:

  • Primary amenorrhoea: this occurs when a woman hasn’t started having periods by the age of 16

  • Secondary amenorrhoea: this occurs when a woman previously had regular periods but they stopped for at least three months


Painful periods (Dysmenorrhoea)  

This is when you get painful and frequent cramps during your period. Primary dysmenorrhoea is caused by the uterus contracting, and is often accompanied by heavy periods. Secondary dysmenorrhea is caused by another condition such as endometriosis or uterine fibroids.iii

Physical and emotional effects of irregular periods

Period problems are very common. That being said, it doesn’t stop the physical and emotional impact they may cause. Some of the long-term effects of irregular periods are physical, such as:

  • Iron deficiency anaemia (can be caused by menorrhagia)

  • Osteoporosis (can be caused by amenorrhea)

  • Infertility (can be caused by amenorrhoea and oligomenorrhoea).

But period problems can affect your mental wellbeing too, as some – particularly painful and heavy periods – can have a negative impact on your ability to work and your social life. lthough it can be difficult, there are various ways you can optimise your emotional health with PCOS.

Common causes of irregular periods

There are also many different things that can cause the different types of period irregularities – here are some of the most common causes:

  • Hormone imbalances (such as unbalanced oestrogen and progesterone levels)

  • Hormone treatments (including hormone-based contraception)

  • Certain medicines such as antidepressants, anti-anxiety medicines, anti-inflammatory medicines and thyroid medicines.
  • Weight loss/gain

  • Eating disorders

  • Stress

  • Over exercising

  • Uterine fibroids or polyps

  • Endometriosis

  • Thyroid problems (overactive or underactive)

  • Smoking

  • Polycystic ovary syndrome (PCOS)


How does PCOS cause irregular periods?

According to Patient, period problems affect about 7 out of 10 women with PCOS. Some will have consistently infrequent periods, light periods, or no periods at all; others will experience heavy and/or painful periods. It’s worth noting, however, that period irregularities don’t always mean you have PCOS. 

Scientifically speaking, it’s highly probable you will experience ovulation issues if you have polycystic ovaries (not everyone with PCOS has small cysts on their ovaries). This condition can prevent the ovaries from releasing an egg each month, thereby leading to cycle abnormalities. In this, the eggs developing in your ovaries aren’t fully mature enough to be released – a fact that still mystifies experts. High levels of androgens and insulin are also known to disrupt your cycle – both of which are hallmark symptoms of PCOS.

Although PCOS has a breadth of potentially distressing symptoms, there’s a strong case to suggest period abnormalities can affect emotional wellbeing more than anything else. One study – which established women with PCOS may have significantly higher levels of psychological distress than the general population – claims the main source of mental health problems in the PCOS community stems from period problems, namely having irregular cycles.iv

What can you do to treat irregular periods?

Medical interventions 

Fortunately, there are several treatments and management tools available for period irregularities. Firstly, it’s wise to speak to a healthcare professional if you have consistent rather than occasional period problems, such as heavy or painful periods, periods that last more than seven days, or infrequent or too-frequent periods.

While the contraceptive pill isn’t a cure, health professionals will often prescribe it to women with PCOS as a first-line of defence – alongside lifestyle changes – to improve menstrual cycle irregularities. Although birth control triggers an ‘artificial’ period, crucially, this bleed keeps many physiological functions working, such as supporting bone health.  

Lifestyle changes

Beyond medical interventions, lifestyle and behavioural changes can also have a sizeable impact on managing PCOS and balancing your menstrual cycle. For starters, exercising excessively is notorious for compromising ovulation. If you suspect this to be the case, try toning down your workout schedule, especially intense cardiovascular activity, and prioritising relaxation-based movement, such as yin yoga or Tai chi.

Chronic stress is also known to impair regular ovulation. Having a bank of stress-fighting hacks in your arsenal could make a big difference to your cycle.  Journaling, meditation, or vigorously ‘shaking’ off your adrenaline may help combat stress in moments of need. Make a conscious effort to relax daily; find what works for you. 
Being overweight can lead to issues with ovulation, too. Problematically, PCOS can make weight gain likely and weight loss difficult. But empirical evidence purports losing even a small amount of weight can support the reduction of symptoms, including issues with ovulationv. Learn more about how to lose weight with PCOS and maintain your motivation. Exercising in a healthy, balanced way can further support weight loss, regulate your menstrual cycle, and improve many other PCOS symptoms. 

On the other hand, if you’ve suddenly lost a lot of weight, your periods may become infrequent or cease altogether. Reverting to a healthy, normal weight may be the only measure you have to take to restore your cycle. 

Alongside this, aim to eat a balanced, nourishing diet – one that’s abundant in low GI fruit, vegetables, healthy fats, and gut-friendly foods (learn more about happy-hormone foods). Creating a bespoke supplement plan is another helpful weapon to support regular ovulation, with a particular emphasis on vitamin B6, folic acid, magnesium and myo inositol. Read more about the best supplements for PCOS here. 

Lastly, some medications can interfere with the menstrual cycle. With this in mind, you may want to have a chat with your GP to establish if any regular medication could affect ovulation. A word of caution: never stop taking prescribed medicine without speaking to your doctor first.

PCOS and regular periods 

Lastly, it’s important to note that irregular periods can be explained by other factors besides PCOS. Abnormalities may be triggered by an underlying medical condition, like an underactive thyroid. In addition to this, PCOS doesn’t always lead to irregular periods. Not all women with PCOS will exhibit the full spectrum of symptoms, and each symptom can range from mild to severe. For some, PCOS will manifest in acne, excessive hair growth and weight gain – not menstrual issues. 

To learn more about your condition and tips for managing symptoms, explore the rest of our PCOS hub




  3. AAFP Clinical Evidence Handbook: Dysmenorrhoea. Available online:

  4. , et al. Differential Contributions of Polycystic Ovary Syndrome (PCOS) Manifestations to Psychological Symptoms. J Behav Health Serv Res. 42(3):383-94. doi: 10.1007/s11414-013-9382-7. Available online:

  5. , et al. Clinical and hormonal characteristics of obese amenorrheic hyperandrogenic women before and after weight loss. J J Clin Endocrinol Metab. 68(1): 173-9.


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Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.

Our Author - Olivia Salter


Olivia Salter has always been an avid health nut. After graduating from the University of Bristol, she began working for a nutritional consultancy where she discovered her passion for all things wellness-related. There, she executed much of the company’s content marketing strategy and found her niche in health writing, publishing articles in Women’s Health, Mind Body Green, Thrive and Psychologies.

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