Heavy periods, also called heavy menstrual bleeding, occur when menstrual bleeding is unusually heavy or prolonged enough to affect physical health, daily activities or quality of life. There is no single universally useful visual measure of blood loss for an individual at home, so clinicians consider practical indicators such as needing to change pads or tampons every one to two hours, using multiple products simultaneously, bleeding for more than seven days, passing large clots or bleeding through clothing and bedding. Symptoms such as persistent tiredness or shortness of breath can indicate iron deficiency or anaemia caused by substantial blood loss. Heavy bleeding can occur without an identifiable disease and can also result from structural, hormonal, bleeding-related or medication-related causes.
Structural conditions of the uterus are important causes of heavy menstrual bleeding. Fibroids are benign smooth-muscle growths that can enlarge or distort the uterine cavity and increase bleeding. Adenomyosis occurs when endometrial-type tissue is present within the uterine muscle and can produce heavy, painful periods. Endometriosis may also be associated with heavy bleeding, although its defining pathology is tissue similar to the uterine lining outside the uterus. Polyps can protrude into the uterine cavity and cause abnormal bleeding. Structural causes are particularly relevant when heavy bleeding is accompanied by pelvic pressure, pain, an enlarged uterus or bleeding that develops after a previously stable pattern.
Disorders of blood clotting can cause heavy menstrual bleeding because the normal haemostatic mechanisms that limit menstrual blood loss do not function adequately. Von Willebrand disease is a particularly important inherited bleeding disorder and can present with heavy periods, easy bruising, frequent nosebleeds or prolonged bleeding after procedures. Other coagulation disorders are less common but can also contribute. A bleeding disorder may be suspected when heavy periods began soon after menstruation first started or when there is a personal or family history of abnormal bleeding. Evaluation may therefore include questions about bruising, dental procedures, surgery and bleeding in relatives rather than focusing exclusively on the reproductive system.
Medications can also increase menstrual bleeding. Anticoagulants reduce blood clotting and may make menstrual blood loss more noticeable or clinically significant. Some other medicines can influence bleeding patterns, and chemotherapy can affect menstrual and reproductive function. An intrauterine device can alter menstrual bleeding depending on its type. Copper intrauterine contraception commonly increases bleeding and cramping, whereas a levonorgestrel-releasing intrauterine system generally reduces menstrual blood loss and is also used therapeutically for heavy periods. Understanding medication and contraception history is therefore an essential part of investigating heavy bleeding rather than assuming that a uterine disease is necessarily responsible.
Hormonal and ovulatory disturbances can contribute to heavy or unpredictable bleeding. When ovulation does not occur regularly, the normal cyclical production of progesterone may be absent, leaving oestrogen-driven endometrial growth relatively unopposed. The resulting lining can become unstable and shed irregularly, sometimes producing prolonged or heavy bleeding. This mechanism can occur during adolescence, perimenopause and conditions associated with irregular ovulation, including polycystic ovary syndrome. Pregnancy-related bleeding must also be considered when appropriate because pregnancy and its complications can produce bleeding that should not be classified as an ordinary period.
Heavy menstrual bleeding can have systemic consequences because chronic blood loss can deplete iron stores and eventually produce iron-deficiency anaemia. Iron deficiency may cause fatigue, reduced exercise tolerance, headaches, dizziness, paleness, breathlessness or impaired concentration. Not everyone with heavy periods becomes anaemic, but persistent symptoms warrant assessment. Clinicians may use blood tests to assess haemoglobin and iron status and may investigate other causes depending on the history. The severity of bleeding is therefore not determined solely by inconvenience; prolonged blood loss can affect nutritional status and oxygen-carrying capacity.
Treatment depends on the suspected cause, severity, age, reproductive plans and individual preferences. Medical options can include tranexamic acid, which reduces fibrinolysis and helps stabilise blood clots within the endometrium, and anti-inflammatory medicines such as mefenamic acid or naproxen, which reduce prostaglandin production and can decrease both bleeding and pain. Hormonal options include the levonorgestrel-releasing intrauterine system and combined hormonal contraception. Structural causes such as fibroids may require specialist procedures, while severe or refractory cases can sometimes involve endometrial ablation or hysterectomy. Treatment is therefore directed at both reducing bleeding and addressing its underlying cause when one is identified.
Heavy periods should be distinguished from an individual's normal variation in menstrual flow. Some people naturally bleed more than others without having an underlying disease, but bleeding that interferes with daily life, produces anaemia, becomes substantially heavier, lasts longer than seven days, occurs between periods or after sex, or accompanies significant pelvic pain should be assessed. Rarely, abnormal uterine bleeding can be associated with malignancy, although many benign causes are much more common.
Clinical evaluation may include blood tests, examination and imaging depending on symptoms and risk factors. The key principle is that "heavy" is clinically meaningful when bleeding is excessive for the individual, prolonged, disruptive or associated with consequences such as iron deficiency, rather than requiring an arbitrary volume measurement alone.
