What should you know about dark heavy period?

Blood can look dark brown, deep red, or almost black when it takes longer to leave the vagina and has had time to oxidise. Colour alone usually gives less information than the amount of bleeding, how long it lasts, whether it is new for you, and whether you feel unwell.

A dark flow may appear at the beginning or end of a period, particularly when bleeding is light or intermittent. Heavy bleeding can instead involve needing to change period products very frequently, bleeding through clothing or bedding, passing clots, or finding that periods interfere with daily activities.

Changes in the uterine lining, fibroids, adenomyosis, polyps, hormonal changes around perimenopause, polycystic ovary syndrome, and some medicines can contribute to heavy menstrual bleeding. Ongoing blood loss can also lead to iron deficiency anaemia, which may cause tiredness, weakness, breathlessness, headaches, or paleness. These possibilities cannot be distinguished by blood colour alone.

Track when the bleeding starts and stops, how often you change pads or tampons, whether you pass clots, and any pain, dizziness, or bleeding after sex. Note pregnancy possibility, recent contraception changes, and medicines that affect bleeding. This record can help a clinician understand the pattern.

Arrange a medical appointment if the bleeding is persistently heavy, has become different from your usual periods, or is affecting work, sleep, exercise, or intimacy. Assessment may include questions about your cycle, an examination, blood tests for anaemia, and sometimes imaging or tests of the uterine lining, depending on your symptoms and age.

Seek urgent medical help if heavy bleeding comes with fainting, severe dizziness, marked weakness, shortness of breath, chest pain, severe or worsening pelvic pain, fever, or a possible pregnancy. Urgent assessment is also appropriate when bleeding is so heavy that you cannot keep up with changing products or you feel unsafe standing or walking.

Dark blood with a strong unpleasant odour, fever, or significant pelvic pain can point to infection or another problem that needs prompt review. Do not delay care because the blood is dark, and do not assume that a familiar colour explains a major change in flow.

You could ask: What might explain the change in flow or colour? Could I have anaemia? Do I need an examination, blood tests, or an ultrasound? Which treatments fit my bleeding pattern and pregnancy plans? What symptoms should make me seek urgent help?