How do I know if my periods are too heavy?

The clinical definition of heavy periods (more than 80 ml per cycle) is not easy to measure at home. In practice, seek assessment if you: soak through a pad or tampon every 1–2 hours for several consecutive hours; need to use two types of protection simultaneously; pass large blood clots (larger than a 50-cent coin); bleed for more than 7 days; or if heavy bleeding is interfering with your daily activities, work, social life, or sleep. Your experience of its impact on your quality of life is a valid reason to seek care.

What causes heavy periods?

The most common causes include uterine fibroids, adenomyosis, endometrial polyps, and hormonal imbalance (including PCOS and perimenopause). Bleeding disorders — particularly von Willebrand disease — are an underdiagnosed cause, especially in women who have had heavy periods since puberty. Less commonly, endometrial cancer must be considered in women over 40 with new or worsening heavy bleeding or intermenstrual bleeding.

Can heavy periods cause anaemia?

Yes. Heavy menstrual bleeding is the most common cause of iron deficiency anaemia in women of reproductive age worldwide. The body can compensate for months to years, but cumulative blood loss eventually depletes iron stores. Symptoms of iron deficiency include fatigue, reduced exercise tolerance, difficulty concentrating, restless legs, and feeling cold. Iron studies and a full blood count should be checked in any woman with heavy periods.

What tests will I need?

Initial investigations typically include a full blood count (to assess for anaemia) and iron studies, a pelvic ultrasound (to identify fibroids, polyps, or adenomyosis), and sometimes a coagulation screen and thyroid function. Pelvic examination and a review of your cycle history and its impact on daily life are part of the assessment. For women over 40 or with additional risk factors, endometrial assessment may be recommended.

Is heavy bleeding always serious?

Most heavy periods are caused by benign conditions — fibroids, adenomyosis, or hormonal imbalance — and are very treatable. However, heavy bleeding should always be assessed rather than simply tolerated, because: it significantly impairs quality of life; it causes preventable iron deficiency anaemia; it can be the presentation of treatable conditions; and, less commonly, it can indicate endometrial cancer. Heavy periods are not something that needs to be accepted as normal.

Heavy Periods: When to Seek Help

Heavy Periods: A Common Problem That Warrants Attention

Heavy menstrual bleeding (HMB) — also called menorrhagia — is one of the most common gynaecological problems, affecting around 1 in 3 women during their reproductive years. Despite its prevalence, many women normalise it, delay seeking help, or are told to simply manage it.

Heavy periods significantly reduce quality of life. They also cause iron deficiency anaemia — the most common nutritional deficiency in women of reproductive age worldwide — with consequences for energy, concentration, mood, and physical performance.

Heavy periods are not something that needs to be accepted.

Key Points

Heavy periods affect approximately 1 in 3 women during their reproductive years.
Seek assessment if soaking a pad or tampon hourly for several hours, passing large clots, bleeding for more than 7 days, or if bleeding impacts daily activities.
The most common causes are fibroids, adenomyosis, endometrial polyps, hormonal imbalance, and bleeding disorders.
Heavy periods are the leading cause of iron deficiency anaemia in women of reproductive age.
Effective treatments exist — medical, minimally invasive, and surgical.
Postmenopausal bleeding (any bleeding 12+ months after the last period) always requires urgent investigation to exclude endometrial cancer.

How Much Is Too Much?

The clinical definition — blood loss greater than 80 ml per cycle — is difficult to quantify at home. More practical indicators:

Sign	What it suggests
Soaking a pad or tampon every 1–2 hours for several consecutive hours	Heavy bleeding threshold
Needing both a pad and tampon simultaneously	Significant flow
Passing clots larger than a 50-cent coin	Substantial blood loss
Bleeding for more than 7 days	Prolonged cycle
Waking at night to change protection	Nocturnal flooding
Avoiding activities, work, or social events because of periods	Significant impact on life

You do not need to meet a technical threshold to seek medical advice. If your periods are impacting your quality of life, that is sufficient reason for assessment.

Causes

Structural Causes

Uterine fibroids are benign smooth muscle tumours of the uterine wall, present in up to 70% of women by age 50. Fibroids distort the uterine cavity and increase the surface area of the endometrium, causing heavier bleeding. They are among the most common causes of heavy periods.

Adenomyosis occurs when endometrial-like tissue grows within the muscular wall of the uterus (myometrium), causing the uterus to enlarge, contract less efficiently, and bleed more heavily. It often coexists with endometriosis and is frequently underdiagnosed.

Endometrial polyps are benign overgrowths of the uterine lining, often causing irregular or heavy bleeding and occasionally intermenstrual bleeding.

Hormonal Causes

Anovulatory cycles — cycles without ovulation, common in perimenopause and PCOS — lead to prolonged oestrogen stimulation without the counterbalancing effect of progesterone. The endometrium thickens excessively and bleeds heavily when it eventually sheds.

Perimenopause is a common cause of new or worsening heavy bleeding in women in their 40s. However, this should not be assumed without assessment to exclude other causes. See Perimenopause: What to Expect.

PCOS — anovulatory cycles cause irregular, sometimes heavy periods. See PCOS: Understanding Polycystic Ovary Syndrome.

Thyroid dysfunction — hypothyroidism causes heavier, more frequent periods.

Bleeding Disorders

Von Willebrand disease (vWD) is the most common inherited bleeding disorder and is significantly underdiagnosed in women. It is estimated that up to 20% of women with heavy periods from adolescence have an undiagnosed bleeding disorder. Ask your doctor about screening if you have:

Heavy periods since puberty
Prolonged bleeding after dental work, surgery, or childbirth
Easy or unexplained bruising
A family history of bleeding problems

Other Causes

Copper intrauterine device (IUD) — consistently increases menstrual blood loss
Anticoagulant medications — warfarin, apixaban, and similar agents increase bleeding
Endometrial cancer — must be considered in women over 40 with new or worsening heavy bleeding, particularly with intermenstrual bleeding or postmenopausal bleeding

Iron Deficiency: The Hidden Consequence

Heavy menstrual bleeding is the most common cause of iron deficiency anaemia in women of reproductive age globally. The body replaces lost iron between periods, but when blood loss consistently exceeds the body’s ability to replenish it, iron stores become depleted.

Iron deficiency develops progressively:

Iron depletion — iron stores (ferritin) fall but haemoglobin remains normal
Iron-deficient erythropoiesis — red cell production becomes impaired
Iron deficiency anaemia — haemoglobin falls and symptoms become apparent

Symptoms of iron deficiency (may occur before frank anaemia):

Persistent fatigue and low energy
Reduced exercise tolerance and breathlessness on exertion
Difficulty concentrating and “brain fog”
Restless legs syndrome at night
Feeling cold, especially in the extremities
Hair loss
Pale skin

Many women have lived with subclinical iron deficiency for years, attributing its symptoms to lifestyle or stress.

Screening: Any woman with heavy periods should have a full blood count and iron studies (serum ferritin is the best single measure of iron stores). A normal haemoglobin does not exclude iron deficiency.

See Why Am I Always Tired? and Restless Legs Syndrome for related iron deficiency content.

Investigations

Typical initial workup for heavy periods:

Test	Purpose
Full blood count	Assess for anaemia and red cell indices
Serum ferritin and iron studies	Assess iron stores
Thyroid function (TSH)	Exclude hypothyroidism
Coagulation screen	Screen for bleeding disorders (especially if heavy since puberty)
Pelvic ultrasound	Identify fibroids, polyps, adenomyosis, ovarian causes
Endometrial biopsy	For women over 40, or with additional risk factors for endometrial cancer

Hysteroscopy (direct visualisation of the uterine cavity) provides both diagnosis and treatment opportunity for polyps and small fibroids.

Treatment Options

Treatment depends on the cause, severity, desire for future fertility, and personal preference.

Medical Treatments

Levonorgestrel intrauterine system (LNG-IUS / Mirena) The most effective medical treatment for heavy periods. Releases a small amount of progesterone locally, causing the endometrial lining to thin. Reduces blood loss by 70–95% in most women. Also provides contraception. This is generally the first option offered to women wanting to preserve fertility or avoid surgery.

Tranexamic acid Non-hormonal. Reduces blood loss by approximately 40–50% by inhibiting the breakdown of blood clots at the endometrial surface. Taken only during heavy days. Does not affect ovulation or fertility.

NSAIDs (e.g. mefenamic acid, ibuprofen) Reduce blood loss by approximately 25–30% and also reduce associated period pain (dysmenorrhoea). Taken during menstruation only.

Combined oral contraceptive pill Reduces blood loss, regulates cycles, and provides contraception. Approximately 40–50% reduction in blood loss. Not suitable for all women (history of VTE, smoking over 35, migraine with aura).

Progestogens (norethisterone, medroxyprogesterone) Can slow or stop heavy periods; often used short-term while awaiting investigations or a longer-term solution.

Surgical Treatments

Endometrial ablation Destroys the endometrial lining using heat, microwave, or radiofrequency. Amenorrhoea in approximately 30% of women; significant reduction in 60–80%. Performed as a day procedure. Not suitable for women wanting future pregnancy.

Hysteroscopic resection Removal of polyps or submucosal fibroids under direct vision. Highly effective for these specific structural causes.

Uterine artery embolisation (UAE) Minimally invasive radiological procedure for symptomatic fibroids. Reduces fibroid blood supply, causing them to shrink. Preserves the uterus.

Myomectomy Surgical removal of fibroids while preserving the uterus. Appropriate for women wanting to retain fertility.

Hysterectomy Definitive treatment — removes the uterus, ending periods permanently. Reserved for cases where other treatments have failed or are not appropriate.

When to Seek Urgent Assessment

Symptom	Action
Soaking through protection hourly for 2 or more hours	Seek same-day medical assessment
Feeling faint or dizzy during a period	Seek urgent assessment — risk of significant anaemia
Postmenopausal bleeding (any bleeding 12+ months after last period)	Urgent referral — exclude endometrial cancer
Bleeding between periods or after sex	Seek assessment — exclude cervical or endometrial pathology
Severe pelvic pain with heavy bleeding	Seek urgent assessment — exclude ectopic pregnancy, infection

Educational only; not a substitute for professional medical advice.