Blood Clots During Periods? A Medical Expert Explains When to Worry

Periods are a challenging time for women, both mentally and physically. The body goes through many changes during this time. While some changes are normal, others may be concerning. One such change that often raises an alarm is passing blood clots during menstruation. This is generally not a cause of concern in majority cases. However, some cases may be an exception. If you are wondering when you should worry about blood clots during periods, read ahead.

To understand this better, we reached out to Dr Pooja C Thukral, Associate Director, Department of Obstetrics and Gynaecology at Cloudnine Group of Hospitals, Faridabad.

Are Blood Clots During Periods Normal?

Let us straightaway get to the main point: are blood clots during periods normal or not? Dr Thukral answers, “Menstrual clots are a mixture of blood cells, tissue from the uterus lining, and proteins in the blood, all of which help regulate its flow. Generally, these clots are not a cause of concern. During periods, blood can coagulate (changes from a liquid to a solid or semi-solid state) in the uterus or vagina as the uterine lining is being shed. These clots are a result of this process.”

The expert further explains, “At the beginning and the end of your cycle, they may appear bright red. This happens because your flow is moving quickly, the blood doesn’t have time to darken. Then may also appear dark red or maroon during the first few days of your period when your flow is light.”

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When To Worry About Period Blood Clots?

Shedding light on when to worry about blood clots, Dr Thukral says, “If your menstrual bleeding gets heavy, it can be serious. It can be a cause of concern if the clots are ball-sized and you are passing them every couple of hours. You should also be worried if you are changing your pads or tampons about every hour.”

The expert shares that although small clots are normal, certain signs need immediate medical attention, such as:

• Blood clots larger than a fist size.
• Passing large blood clots multiple times per day.
• Soaking through menstrual products every hour for several consecutive hours.
• Needing multiple pads simultaneously to deal with leakage.
• Changing pads even during the night.
• Periods that last beyond seven days.
• Happens frequently throughout the whole period.
• Is linked with heavy cramps or heavy bleeding.
• Has a foul smell.
• Resembles thick tissue or membrane.
• Causes fatigue, lightheadedness, or weakness.

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Potential Causes of Blood Clots During Periods

Dr Thukral says that some of the potential or underlying causes of period blood clots are:

• Endometriosis — This condition causes an overgrowth of tissue that can impact the ovaries, fallopian tubes, and pelvic tissue and lead to period blood clots.
• Adenomyosis — Adenomyosis is a benign disease of the female reproductive system, where the uterus will thicken and may even double or triple its normal size. Common adenomyosis symptoms consist of heavy or prolonged menstrual bleeding, bleeding between periods, passing blood clots during a period, and abdominal pain.
• Uterine Fibroids — Period blood clots and heavier-than-normal-menstrual bleeding can also indicate you have fibroids. 
• Polyendocrine Metabolic Ovarian Syndrome (PMOS) — This condition, caused by an imbalance of reproductive hormones, causes missed or irregular periods and blood clots.
• Thyroid conditions — In women, hypothyroidism can cause several health problems, including period blood clots.
• Birth control — Though the risk is small, birth control pills (if taken irregularly) can result in blood clots.
• Medication — It is also important to take note of the medications you’re taking if you notice an increase in period blood clots.

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What Study Says About Blood Clots During Periods

A 2025 study, published in the medical journal Haemophilia, examined multiple medical studies to understand more about blood clots during this period. It noted that many women wonder if blood clots during their periods are normal. While small clots are a typical part of shedding the uterine lining, heavy bleeding often requires medical concern. 

The study noted that heavy periods can sometimes be the first sign of an underlying bleeding disorder. This makes it important for doctors to correctly measure blood clotting factors. The research adds that a woman's natural ability to clot blood normally fluctuates throughout her menstrual cycle. This happens as a result of changing hormone levels such as oestrogen and progesterone. Scientists originally suspected that women with unexplained heavy periods might have lower levels of these essential clotting proteins, leading to heavier bleeding. 

The researchers discovered that women with heavy menstrual bleeding had slightly higher concentrations of certain clotting proteins, specifically Factor VIII and Factor V, compared to women with normal periods. The study concluded that while blood clotting is a complex but normal part of menstruation, more research is required to fully understand exactly how these proteins are linked to heavy bleeding. 

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Conclusion

Small blood clots during your menstruation are a completely normal part of shedding the uterine lining. However, if you notice significant changes in your flow or experience unusually large clots that soak through pads hourly, or feel extreme fatigue, it is important to consult a healthcare provider for a proper evaluation. Identifying underlying conditions such as fibroids or endometriosis early can help you manage heavy menstrual bleeding and protect your overall well-being.