Heavy Periods: What Counts as Too Much and What Causes It
“Heavy periods” is a subjective phrase, and women are often told their experience is normal when it is not. Heavy menstrual bleeding affects a substantial proportion of women, is a leading cause of iron deficiency anaemia, and has effective treatments that many people are never offered.
What counts as heavy
The clinical definition is bleeding that interferes with physical, social, emotional or material quality of life. That deliberately centres the impact rather than a measured volume, because nobody measures volume in practice.
Practical markers:
- Soaking through a pad or tampon every hour or two for several consecutive hours
- Needing double protection
- Needing to change protection during the night
- Bleeding lasting more than seven days
- Passing clots larger than about 2.5 cm
- Flooding through clothes or bedding
- Restricting activities, work or travel because of bleeding
- Symptoms of anaemia: fatigue, breathlessness on exertion, dizziness, palpitations, pallor, hair shedding, pica such as craving ice
If any of these apply, it is worth investigating, regardless of being told it is normal.
Causes
A useful framework divides causes into structural and non-structural.
Structural:
- Fibroids. Benign muscle growths in the uterus, very common. Those bulging into the cavity cause the heaviest bleeding
- Adenomyosis. Endometrial tissue growing into the uterine muscle wall. Causes heavy, painful periods and a bulky tender uterus. Frequently underdiagnosed
- Polyps. Small benign growths of the lining
- Malignancy or precancerous change. Less common, more relevant after 45, with risk factors including obesity, PCOS, unopposed oestrogen and a family history
Non-structural:
- Ovulatory dysfunction, common in the teens and in the years approaching menopause, where irregular ovulation leads to unpredictable, sometimes very heavy bleeding
- Bleeding disorders. Von Willebrand disease is present in a meaningful minority of women with heavy periods since adolescence and is routinely missed. Heavy periods from the very first one, with easy bruising, nosebleeds or bleeding after dental work, should prompt testing
- Thyroid disease, particularly underactive
- Medications, including anticoagulants
- Copper intrauterine devices, which commonly increase flow
- Endometritis and chronic infection
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What assessment should include
- A full blood count and ferritin. Ferritin matters, because iron stores deplete before haemoglobin falls, and fatigue often precedes anaemia
- Thyroid function
- Pelvic ultrasound, ideally transvaginal, to look for fibroids, adenomyosis and polyps
- Coagulation screening and von Willebrand testing where the history suggests it
- Endometrial sampling where there is risk of hyperplasia or cancer: age over 45, persistent bleeding between periods, failed treatment, or significant risk factors
- Pregnancy test where relevant
Treatments
Non-hormonal:
- Tranexamic acid, taken only on heavy days, reduces blood loss by roughly a third to a half. Does not affect hormones or fertility, and is often the simplest effective option
- NSAIDs such as mefenamic acid, which reduce flow modestly and also help period pain
Hormonal:
- Levonorgestrel intrauterine system. The most effective medical treatment, reducing blood loss dramatically, with many women having very light periods or none. Recommended as first-line medical treatment in several guidelines
- Combined oral contraceptives
- Cyclical or continuous progestogens
- GnRH analogues for short-term use, typically before surgery
Procedural:
- Endometrial ablation, destroying the uterine lining, for women who have completed their family
- Uterine artery embolisation for fibroids
- Myomectomy, removing fibroids while preserving the uterus
- Hysterectomy, definitive, and now rarely the first option
Iron deserves attention in its own right
Heavy periods are the commonest cause of iron deficiency in women of reproductive age, and the fatigue it causes is frequently attributed to stress or busy life.
Oral iron is absorbed better on alternate days than daily, because daily dosing raises hepcidin and blocks absorption. Take it with vitamin C, and away from tea, coffee, calcium and antacids. Replenishing stores takes months, and treatment should continue beyond normalisation of haemoglobin to rebuild ferritin. Intravenous iron is an option where oral iron is not tolerated or is insufficient.
When to seek care promptly
- Soaking through protection hourly for several hours
- Feeling faint, markedly breathless, or having chest pain with bleeding
- Bleeding after sex, between periods, or after menopause, which always needs assessment
- Severe pain not controlled by simple analgesia
- Bleeding with pregnancy or possible pregnancy
The short version
If bleeding is limiting your life, it is heavy enough to investigate, whatever anyone has told you. Ask for ferritin as well as haemoglobin, an ultrasound, and clotting tests if your periods have been heavy since they began. Tranexamic acid and the hormonal IUS are highly effective and are the two options most often not mentioned.