Blood Clots During Periods: Normal or Not

• Researched and written by: Shivangani Singh, BA in Journalism and Mass Communication
• Edited by: Vaibhavi Kodnani
• Medical inputs by: Dr Yash Bahuguna, MBBS, MS, DNB, ISGE Certified Practitioner for PCOS
• Medically reviewed by: Dr Poonguzhali Liston, MBBS, MS OBG, FMAS, DRM, FRM, CIMP

TL;DR

• Clots during menstruation are common and consist of blood mixed with uterine tissue. These clots can be either bright red or dark brown in colour.[1]

• Small dark brown clots are commonly seen at the beginning or end of periods. 

• Small bright red clots may occur occasionally during the first few days during periods when the menstrual flow is usually heavy.[2]

• Clots larger than a 10 rupee coin that appear frequently may be linked to heavy menstrual bleeding. They may often occur with symptoms such as severe pain and fatigue.[5]

• Tracking symptoms in a period diary can help identify patterns and spot anything unusual earlier on. 

• It can support early diagnosis of any underlying conditions and help with receiving timely care.

What Are Period Blood Clots?

The presence of blood clots during a period is quite common and usually just reflects the natural shedding of the uterine lining. These clots are made up of menstrual blood and uterine tissue, giving them a slightly heavier and more solid texture compared to regular menstrual flow.[1]

There are generally two types of menstrual clots you may notice: jelly-like, bright red clots and dried, dark brown clots.

Jelly-like bright red clots

Jelly-like bright red clots usually appear when the flow is heavy, most commonly during the first 1–3 days of your period. These clots indicate fresh-flowing blood. They may be slightly larger in size.

Dried dark brown clots

Dried dark brown clots are more likely to appear at the beginning or end of the period, when the flow is lighter and slower. It usually indicates older blood. They are typically smaller in size. 

Why Do Blood Clots Form? Understanding the Science

Blood clots during a period are a natural response of the body to manage menstrual flow. While they may look concerning, the formation of clots is often linked to how quickly the uterine lining is shed and expelled during menstruation.[1,2]

Science behind bright red clots

During menstruation, the uterus lining breaks down and sheds as part of the monthly cycle. During the first 1–3 days of the period, the menstrual flow is usually heavy. That’s because the uterus is shedding a larger amount of blood. 

Sometimes, this blood may not be able to exit the body immediately. Instead, it may pool inside the uterus or vagina and begin to thicken, forming clots. These clots often appear bright red and jelly-like because the blood is still fresh.[5]

Science behind dark brown clots

Dark brown clots usually indicate older blood that has taken longer to leave the body. They typically appear at the beginning or end of a period when the flow is slower and lighter. As the blood is not expelled quickly, it stays in the uterus or vagina and gets exposed to oxygen. The process of oxygenation darkens the blood. 

Over time, this older blood thickens and mixes with natural vaginal secretions, resulting in smaller, dark brown clots.[5]

Note: Brown blood or clots may sometimes appear mid-cycle during ovulation. However, if it is accompanied by other symptoms such as a foul smell, itching, or pain, it may sometimes indicate an infection or another underlying issue. It’s best to speak to a doctor to identify the cause. 

Passing Blood Clots During Menstrual Period: Normal or Not?

While occasional small clots are common, blood clots that are bigger or occur frequently along with significant discomfort may indicate heavy menstrual bleeding (menorrhagia). Understanding the size, frequency, and associated symptoms can help you assess whether your period clots are typical or require medical attention.[3,6]

Maintaining a Period Diary: An Easy Way to Track Clots and Other Symptoms

Maintaining a period diary is an easy and effective way to understand your menstrual cycle better. It helps you track patterns of your blood flow, blood clots, pain, associated symptoms, length of bleeding, and length of your cycle. 

Over time, this record can help you understand what is normal for your body and detect anything unusual early. It can make it easier to explain your symptoms clearly to a doctor. 

What to track in your period diary? 

You can answer the following questions in your period diary every month to identify patterns. 

• What is the size of your menstrual clots? Are they smaller or bigger than a 10-rupee coin? 

• Which days of your period do you notice menstrual clots?

• How often do you get blood clots during your period? 

• How many pads or tampons do you use in a day and how frequently do you change them?

• How many days does your period last from start to finish? 

• Do you feel pain along with clots? If yes, how severe is it on a scale of 0–10? 

• Do you have symptoms like fatigue, dizziness, or weakness during your period? 

• For how many cycles have you been noticing blood clots during your period?

• Do you notice any unusual spotting or clots outside your regular cycle? 

Common Causes of Large Blood Clots During Periods

While occasional clots can be normal, persistent or frequent clots may point to an underlying issue. Certain uterine, hormonal, or bleeding conditions may increase bleeding or affect how the uterus sheds its lining. 

Uterine conditions

Certain conditions affecting the uterus can cause the uterine lining to grow excessively or shed unevenly. This may lead to heavier bleeding and clot formation.

• Fibroids: Non-cancerous growths in the uterus that can increase blood flow and lead to larger clots.[12]

• Adenomyosis: Occurs when the uterine lining grows into the muscle wall, causing heavy and painful periods. 

• Endometrial hyperplasia: Thickening of the uterine lining, which can result in heavier shedding. 

• Endometriosis: A condition where tissue similar to the uterine lining grows outside the uterus, often causing heavy, painful periods and blood clots.[4]

• Pelvic inflammatory disease: Pelvic infections may irritate tissues and contribute to abnormal bleeding.

Hormonal causes

The balance of estrogen and progesterone plays a key role in regulating periods. Hormonal imbalances, such as excess estrogen and low progesterone, can affect ovulation and timely shedding of the uterine lining. It can lead to build-up of a thicker uterine lining, which may result in heavier bleeding and clots. Common causes include:

• Polycystic ovary syndrome (PCOS)[8]

• Thyroid disorders[14]

Bleeding disorders and blood thinners

Certain bleeding disorders in women such as von Willebrand disease and hemophilia cause clotting issues. When the blood does not clot properly, it can cause heavy menstrual bleeding. 

The excess blood may pool inside the uterus or vagina and form clots. That’s why some individuals with bleeding disorders may notice larger clots during their periods. 

Other common symptoms of bleeding disorders during periods include prolonged periods, flooding or gushing of blood, and fatigue due to blood loss. 

Similarly, medications such as blood thinners can also increase menstrual bleeding, which may also lead to large clot formation.

Berry’s Tips: What Should You Do if You Are Experiencing Blood Clots?

If you are experiencing heavy periods with blood clots during your period, the goal is to manage your flow comfortably, prevent fatigue from blood loss, and keep track of any unusual symptoms. Consider following the doctor-backed guide below. 

Change period products regularly

Make sure to change your pads or tampons or empty your menstrual cup at regular intervals. This helps maintain hygiene and comfort, prevents leakage, and allows you to monitor how heavy your flow is throughout the day.

Stay hydrated

Drinking enough water is important, especially during your period. Staying hydrated helps your body cope better with blood loss and can help manage fatigue, dizziness, and low energy levels. Aim to drink about 1.5–2 litres of water every day and increase your intake if needed. 

Increase intake of iron-rich foods

Heavy bleeding can lower your iron levels over time. Including iron-rich foods like spinach, legumes, jaggery, dates, and meat (especially organ meat) in your diet can help support excessive blood loss and manage fatigue.[10]

Use period pain relief strategies

If heavy bleeding and blood clots are accompanied by severe cramps, try simple pain relief methods like a heating pad, TENS, gentle stretching, or medication (after consulting a doctor). 

Track clot size, flow, and related symptoms

Use a period diary to track clot size, flow, pain levels, and any other changes. This makes it easier to notice patterns over time and periodically explain your symptoms to a doctor if needed. Keeping a record of your symptoms is one of the most helpful things you can do. 

Addressing Period Clot Myths

It's common to feel worried when you notice clots during your period, but not everything you hear about them is true. Many myths turn normal experiences into a cause of concern, even when there is no real problem. Let's clear up some of the most common misconceptions so you can better understand what your body is telling you.

Clots always mean something is wrong with your menstrual health.

Clots are a normal part of menstruation. During the first few days of the period, when the flow is relatively heavy, small clots may appear occasionally. 

Period clots that are consistently large, very frequent, or accompanied by symptoms like severe pain or excessive bleeding may indicate an underlying condition. Even then, it's important not to panic or self-diagnose. Consulting a doctor is the best way to understand the cause. 

Clots are dangerous and can cause health complications.

Small clots are not dangerous and generally do not lead to any health issues. Staying hydrated and maintaining a balanced, iron-rich diet can help manage fatigue during heavier days. 

However, large clots may be linked to heavy menstrual bleeding, which can lead to iron deficiency anemia over time if not managed. Additionally, if an underlying condition is causing the heavy flow, it may worsen over time if left untreated.

Clots are cancerous.

In most cases, menstrual clots are not linked to cancer. They are more commonly associated with conditions like hormonal imbalance, uterine conditions, or infections. 

That said, in rare cases, abnormal bleeding with unusually large or persistent clots may be linked to serious conditions such as uterine or cervical cancers. This is uncommon, but it's important to get checked if symptoms seem unusual or persistent.[15]

Clots indicate a miscarriage.

Clots during a period do not automatically indicate a miscarriage. However, in sexually active women, passing masses of blood or fleshy tissue rather than typical blood clots can indicate early pregnancy loss and may require immediate medical care. 

When Should You See a Doctor?

Small period clots may occur occasionally during heavy flow days. However, if you notice changes in your symptoms or cycle that interfere with your daily life, it's important to seek medical advice.[9]

See a doctor if you notice: 

• Signs of heavy menstrual bleeding: Soaking through a pad or tampon every 1–2 hours, passing clots bigger than a 10 rupee coin frequently, bleeding lasting longer than 8 days

• Pain symptoms: Severe or worsening pelvic pain, intense cramps and other pain symptoms during periods that may persist or appear at other times during the cycle

• Symptoms of PCOS: Irregular periods, acne, facial hair growth, unexplained weight gain

• Signs of anemia: Fatigue, dizziness, or pale skin 

• Signs of recurrent vaginal infections: Foul-smelling, discoloured discharge at any time during the cycle, itching, burning during urination

During your appointment, your doctor will usually ask about your menstrual history, symptoms, and overall health. Keeping a period diary can be very helpful in providing accurate details. They may also perform a physical examination and recommend tests such as blood tests or an ultrasound to identify the cause and recommend a treatment plan. 

The Bottom Line

Blood clots during periods are often a normal part of menstruation. You may notice dark brown clots at the beginning or end of your period and bright red clots on heavier flow days. These clots are often small in size and occur occasionally. 

However, if you experience large clots in periods accompanied by other symptoms like heavy bleeding, severe pain, or fatigue, it may indicate an underlying issue that needs medical attention. 

Tracking the size and frequency of clots, menstrual flow and length, and any associated symptoms in a period diary can help you notice anything unusual early and seek timely care. 

FAQs on Blood Clots During a Period

Why am I passing so many blood clots?

Passing frequent blood clots during your period may be due to heavy flow, where blood collects and clots before exiting the body. 

What do fibroid clots look like?

Fibroid-related clots are often larger, thicker, and more frequent, sometimes appearing as dark red or deep brown masses.

Does PCOS cause blood clots?

Yes, PCOS can lead to irregular cycles, which may thicken the uterine lining and cause heavier bleeding. This may result in blood clots during a period.

How do I know if my period clots are normal or not?

Occasional, small clots are normal, but passing frequent clots larger than a 10 rupee coin along with heavy bleeding or pain may need medical attention.

References

1. American College of Obstetricians & Gynecologists. Heavy Menstrual bleeding. Accessed March 26, 2026

2. de Vaan A, Goedkoop MM, Welsing PM, van Hanegem N, Schutgens RE, van Galen KP. Clotting Factor Concentration During Menstrual Phases in Women With and Without Heavy Menstrual Bleeding: A Systematic Review and Meta‐Analysis. Haemophilia. 2025 Jul;31(4):780-6.

3. Jain V, Munro MG, Critchley HO.Contemporary evaluation of women and girls with abnormal uterine bleeding: FIGO Systems 1 and 2. International Journal of Gynecology & Obstetrics. 2023 Aug;162:29-42.

4. Magnay JL, O’Brien S, Gerlinger C, Seitz C. Pictorial methods to assess heavy menstrual bleeding in research and clinical practice: a systematic literature review. BMC women's health. 2020 Feb 10;20(1):24.

5. National Institute of Health and Care Excellence. Heavy menstrual bleeding: assessment and management. Accessed March 26, 2026

6. National Health Service. Heavy Periods. Accessed March 26, 2026

7. Mayo Clinic. Blood Clot during menstruation: A concern? Accessed March 26, 2026

8. American College of Obstetricians & Gynecologists.Polycystic Ovary Syndrome (PCOS).Accessed March 26, 2026

9. Centers for Disease Control and Prevention.Signs and symptoms of bleeding disorders in women. Accessed March 26, 2026

10. American Society of Hematology. Iron-Deficiency Anemia. Accessed March 26, 2026

11. National Institute of Health. Iron. Accessed March 26, 2026

12. American College of Obstetricians & Gynecologists. Uterine Fibroids. Accessed March 26, 2026

13. American College of Obstetricians & Gynecologists. Endometriosis. Accessed March 26, 2026

14. U.S. Department of Health and Human Services. Thyroid Disease. Accessed March 26, 2026

15. Hapangama DK, Bulmer JN. Pathophysiology of heavy menstrual bleeding. Women’s Health. 2016 Jan;12(1):3-13.