heavy periods

What you need to know about heavy periods

Typically, women lose less than 16 teaspoons (80ml) of blood during their period each month, with the average ranging from 6 to 8 teaspoons.

Heavy menstrual bleeding is characterized by the loss of 80ml or more in each period, periods lasting over 7 days or both. However, most women would know what is considered as normal bleeding for them, and are able to tell when it is heavy menstrual bleeding.

Signs of excessive bleeding during your period may include:

  • Changing sanitary products hourly or every 2 hours
  • Passing blood clots larger than 2.5cm (similar to a 10p coin)
  • Experiencing leakage onto clothes or bedding
  • Needing to use two types of sanitary products at the same time

Causes of heavy bleeding vary, with approximately half of women experiencing this issue having no underlying condition. However, certain conditions and treatments can contribute to this problem.

Conditions affecting the uterus and ovaries that may lead to heavy bleeding include:

  • Fibroids: Non-cancerous growths in or around the womb, often causing heavy or painful periods.
  • Endometriosis: The presence of womb lining tissue outside the womb, potentially in the ovaries or fallopian tubes, though it typically results in painful periods.
  • Adenomyosis: Occurs when womb lining tissue embeds in the womb wall, potentially causing painful periods.
  • Pelvic Inflammatory Disease (PID): An infection in the upper genital tract, with symptoms including pelvic or abdominal pain, bleeding between periods, bleeding after sex, vaginal discharge and fever.
  • Endometrial Polyps: Non-cancerous growths in the womb or cervix lining.
  • Uterine Cancer: Often marked by abnormal bleeding, especially after menopause.
  • Polycystic Ovary Syndrome (PCOS): A common condition affecting ovarian function, resulting in irregular and occasionally heavy periods
  • Other potential causes of heavy and extremely heavy periods include:

  • Blood clotting disorders like Von Willebrand disease.
  • Underactive thyroid gland (hypothyroidism), leading to tiredness, weight gain and depression.
  • Liver or kidney disease.
  • Certain medical treatments may also contribute to heavy periods.


Let us discuss some of the above in more detail, 


Polycystic Ovary Syndrome is a common concern affecting periods and fertility. It is associated with irregular hormone levels, mainly elevated insulin levels. PCOS is characterised by the presence of small cysts on the ovaries, irregular menstrual cycles and elevated levels of androgens (male hormones). Symptoms typically show up after puberty, and irregular or stopped periods are often the first sign. Other signs include acne, weight gain, extra hair growth and increased period pain, making it challenging to conceive.

A female hormone test kit tests specific hormones related to PCOS, providing insights whether you have it or not. Lifestyle changes and sometimes medication can help manage symptoms. Keep in mind that such a kit can't diagnose PCOS definitively, but it's a valuable initial step in understanding potential indicators. It can guide you in figuring out if PCOS might be behind your symptoms and help you decide what steps to take next.


This occurs when the ovaries gradually reduce the production of oestrogen. The perimenopause typically begins in a woman's 40s, but it can start earlier in some cases, usually around the mid-30s. Some people are in perimenopause for only a short time, but for many, it lasts four to eight years. Changes to the menstrual cycle, such as heavy periods and passing large clots, often serve as early indicators of the perimenopause.

Oestrogen and progesterone hormones typically regulating the menstrual cycle, exhibit a predictable pattern before perimenopause.

However, during perimenopause, the fluctuation and decline in oestrogen and progesterone can render the cycle unpredictable and irregular. This may lead to longer or shorter cycles, more frequent periods,


This is a medical condition characterised by the growth of tissue resembling the womb's lining in areas outside the uterus, such as the ovaries. Affected by hormonal changes, the displaced tissue mimics the behavior of the uterine lining; hence, thickening, breaking down and bleeding during the menstrual cycle.

Endometriosis can bring about significant discomfort and disruption to daily life. This condition is not restricted by age and can affect teenagers. Symptoms may vary widely, with some experiencing severe pain, fertility issues, and others showing milder symptoms.

Since endometriosis is considered as a chronic condition, it can substantially impact women’s lives. However, various treatments are available to reduce symptoms and improve the quality of life for those affected.


Uterine fibroids are non-cancerous growths of the uterus that often appear during a woman's childbearing years. The specific reason for fibroids formation is unclear, but their development appears to be linked to elevated levels of oestrogen. Fibroids consist of muscle and fibrous tissue, their location vary within the uterus and range in size from as small as a pea to as large as a melon.

While many women with fibroids may not experience any symptoms, others may encounter significant challenges, including heavy menstrual bleeding (menorrhagia). Fibroids tends to shrink in size when oestrogen levels are low, particularly following menopause when a woman's monthly menstrual cycle ceases.

Heavy menstrual bleeding is a common symptom associated with fibroids. The presence of fibroids in or near the uterine lining can lead to an increase in the surface area of the uterine cavity, causing heavier and more prolonged periods. The extent of bleeding can vary, ranging from a moderate increase to severe and debilitating flow.

How does the thyroid influence periods?

The thyroid releases hormones that interact with various hormones, including those in the ovaries.

When the thyroid is underactive, a condition known as hypothyroidism, it doesn't produce enough hormones, this can affect menstrual cycles in a couple of ways. Firstly, it can hinder ovaries from producing progesterone, a hormone that typically reduces menstrual flow. Additionally, an underactive thyroid may impair blood clotting ability, making it challenging to control bleeding. This can lead to the development of heavy, uncomfortable and inconvenient periods every month.

The positive aspect of thyroid issues is that they are generally easy to diagnose and treat.

Relevant blood tests

An imbalance in oestrogen, progesterone or other hormones can be a contributing factor to menorrhagia. In some women, elevated oestrogen and low progesterone levels may cause a thickening of the uterine lining, often resulting in heavy menstrual bleeding.

If you experience heavy monthly bleeding, it is possible that your dietary iron intake may not be sufficient to replenish the blood lost during these episodes. Inadequate iron levels can result in anemia.


Heavy menstrual periods may not always need to be treated, but treatment options are available if they significantly impact your daily life.

Your GP can provide the following treatments:

  • Certain contraceptives, like an intrauterine system (IUS) or combined contraceptive pill.
  • Medications to help reduce bleeding, such as tranexamic acid.
  • Prescription-only anti-inflammatory pain relievers, like mefenamic acid or naproxen.



Brazier (2024) Fibroids: Everything you need to know. Available at: https://www.medicalnewstoday.com/articles/151405

Shiekh (2023) Perimenopause. Available at: https://www.webmd.com/menopause/guide-perimenopause

NHS (2021) Heavy Periods. Available at: https://www.nhs.uk/conditions/heavy-periods/#:~:text=Treatment%20for%20heavy%20periods&text=Treatments%20from%20a%20GP%20include,as%20mefenamic%20acid%20or%20naproxen


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