Medically reviewed by Sophia Yen, MD, MPH – Written by Varuska Patni. Updated April 6 2021

Hormonal Birth Control Products and the Risk of Blood Clot Formation

Millions of women use hormonal birth control methods to prevent unintended pregnancy, regulate hormones, and control the symptoms of PCOS. Although birth control pills and other hormonal contraceptive methods are proven safe and effective for the vast majority of women, not every woman can safely take hormonal birth control. Unfortunately, some birth control products can increase the risk of blood clots developing in women with particular risk factors. The following article explores what blood clots are, why they are dangerous, and how birth control affects their formation.

What is a blood clot?

Human blood consists of several clotting agents that give blood its consistency and also allow the body to repair itself if someone gets cut or injured. However, some people experience an increased risk for blood clots in their arteries and/or veins. The hormone estrogen is known to increase the blood’s ability to coagulate a.ka. make a blood clot.

Blood clots make it difficult or impossible for blood to flow through tiny veins, arteries, and capillaries throughout the body. When a blood clot forms, it can become stuck, and cause a heart attack or a stroke, which can be fatal or lead to permanent disability.

Birth Control and Blood Clots

Two types of blood clots: deep vein thrombosis (DVT) and pulmonary embolisms (PE) are the ones that we worry about with estrogen containing birth control. With a DVT, a clot forms inside the deepest veins of the body in the legs or the arms. The signs of DVT include:

  • Swelling (where the clot has formed).
  • Leg or arm pain and tenderness at the clot that feels similar to a cramp.
  • Red or blue skin discoloration at the clot site.
  • The clot site is warm to the touch.

Sometimes, the clots that form in a DVT can break apart and travel up to the lungs. This is called a pulmonary embolism. Pulmonary embolisms can result in death in 30% of the cases if the undiagnosed and untreated, but if diagnosed and treated, 8% of those affected die. The symptoms of a pulmonary embolism include:

  • Shortness of breath
  • Chest pain that gets worse when you take a deep breath.
  • High heart rate
  • A bloody cough

If you experience any of the symptoms of DVT or a pulmonary embolism, you need to go to the ER immediately. Call 911.

What does a blood clot feel like?

Blood Clots: Signs, Symptoms, and Complications

A blood clot can appear in many different areas of the body that include but are not limited to the legs, chest, abdomen, and brain. Although all of these are different, they show similar hallmark signs. For women, clot most often form in the abdomen (stomach area) and chest due to a high amount of estrogen, which increases the chances of a blood clot developing. 

Hallmark signs of a blood clot are:

  • Shortness of breath that isn’t caused by exercise or vigorous movement 
  • Rapid Heart Rate
  • Soreness in the affected area
  • Possibly a cough
  • Angina (chest pain)
  • Radiation of pain to nearby body parts and organs
  • Warmth in the area 
  • Inflammation in the area
  • Tenderness in the area 
  • Throbbing or cramp-like pain without probable cause 
  • Swelling  in the area
  • Red or purple discoloration 
  • In some serious cases, coughing up blood 

If you or a doctor feel a DVT in the leg, sometimes you can feel a cord in the leg. 

What are risk factors for blood clots?

  • Pregnancy and the 1st 6 weeks after having the baby, because you just gave birth and your body wants to make sure you can clot and not bleed to death.
  • Personal or family history of blood clots (it runs in the genes)
  • Obesity
  • Surgery, mainly because you lie around and don’t move much which allows blood to sit and clot.
  • Blood clotting problems like Factor V Leiden, Protein C or S issues.
  • Sitting still like LONG car rides or LONG plane rides. At Pandia Health, we advise if you are going on a plane ride >3 hours, drink LOTS of water, walk around, and take an ibuprofen or aspirin WITH FOOD before. (The latter 2 medications decrease blood clots.)

How do hormones impact the formation of blood clots?

Combined hormonal birth control pills (with both estrogen and progesterone) are the 2nd most common contraceptive methods used in the U.S. Birth control pills themselves do not cause blood clots to form directly. But they can increase the chances of blood clot formation by as much as three to four times. However, the risk of a VTE (venothromboembolism = blood clot in your veins) is very low to begin with = 0.8/ 10,000 women per year.

This happens because the hormones in the estrogen/progesterone birth control pill, patch, or ring, can affect blood coagulation factors.

Most hormonal birth control pills contain a combination of progesterone and estrogen hormones. These hormones increase the clotting factors in the blood. These same hormones cause pregnant women to have an increased risk of blood clots. Only about one in 1000 women who take hormonal birth control pills are at risk of having a blood clot form.

But women with a family or personal history of blood clots, older women over age 35, and women who smoke have a much higher risk of having a blood clot while taking the combination birth control pill, using the birth control patch. Women in these groups should not use birth control methods that contain estrogen. Both the patch, the ring, and combination oral contraceptives can increase the blood’s ability to clot and lead to a DVT or pulmonary embolism.

What decreases the risk of a blood clot forming while taking birth control pills/patches?

Some women may take an anticoagulant medication and taking an anticoagulant while also taking hormonal birth control decreases the risk of having a dangerous blood clot form. But women who are not taking anticoagulants and also have an increased risk of blood clot formation have more limited choices for birth control.

Recent research also indicates that some types of hormonal contraceptives that contain drospirenone and desogestrel can increase the blood’s ability to coagulate. Those contraceptives are:

Find out the difference between Yaz and Yasmin.

Which birth control method has the lowest risk of blood clot formation?

Estrogen is the biggest culprit behind women’s increased risk of having blood clots form while taking the pill and also while pregnant. However, progesterone and synthetic progesterone hormones do not raise the risk of having the blood coagulate to unsafe levels. Women can take progestin-only pills, also known as mini-pills if they are concerned about blood clots.

Progestin-only pills include: Micronor,  Nor-Q.D., NoraBe, Sharobel. Deblitane, Errin, Jolivette, Heather, Jencycla, Camila, and Slynd

Also, IUDs, or intrauterine devices, do not increase the risk of blood clots. IUDs are also long-lasting and are easy to remove if a woman wishes to get pregnant or stop using the IUD for any reason. IUDs can last up to ten years and are some of the most effective, long-lasting birth control products on the market. Both the Mirena and the copper IUD do not increase the risk of blood clots.

The birth control shot is also safe for women with concerns about blood clots. The shot provides a dose of progestin that is given every 12 weeks to prevent ovulation from occurring.

Other barrier contraceptive methods such as condoms, diaphragms, and cervical caps are safe for women to use if they have a history of blood clots, smoke, or are over age 35. are safe to use. Emergency contraceptives do not contain estrogen and are also safe to use.

Blood Clot symptoms: 

  • Leg pain
  • Chest pain
  • Rapid heartbeat 
  • Difficulty speaking
  • Shortness of breath 
  • Muscle weakness
  • Soreness in upper and lower extremities 

What should women do if they are concerned about blood clots?

TLDR: Talk to your doctor and KNOW your family history. Does anyone in your family have a history of blood clots in their legs or lungs? 

It is crucial that women thoroughly discuss their personal health history and immediate family health history when trying any new medication, not just hormonal birth control with their doctor. When looking into different types of prescription birth control methods to try, women can significantly benefit from doing their research and speaking to their doctors about their needs and concerns. Women need to take charge of their reproductive health.

Not only can hormonal birth control prevent unintended pregnancy, but it can also help women regulate their hormones, alleviate menstrual pains, and also treat endometriosis and prevent PCOS symptoms from flaring up. Please sign up with Pandia Health today to find out what types of long-lasting and effective birth control methods are right for your lifestyle and health needs.

Frequently Asked Questions (FAQ’s):

Can and why does birth control cause blood clots?

As estrogen levels increase, the risk of getting a blood clot increases, because the estrogen affects blood clotting mechanisms in your blood. Combined hormonal birth control pills have estrogen, which increase risk of blood clots. 3-4 in 10,000 women who are on hormonal birth control pills get a blood clot. The risk of blood clots is greater if you get pregnant, give birth than if you took any form of hormonal birth control. 

Those with a personal or family history of blood clots and those who smoke and who are 35 year old or older are all at higher risk for blood clots while taking the combined birth control pills or patch. Higher risk women should avoid birth control pills that use contain estrogen. Intrauterine devices (IUDs) and birth control shots are safe for those with concerns or risk factors for blood clots because, they do not increase the risk of blood clots.

Birth control-related blood clots account for 0.3-1% of all clots found in women. The chances of blood clots developing depends on which contraceptive you use and how much estrogen is in each dosage. For example, the amount and type of hormones in pills are known to have a higher risk of a blood clot developing  compared to other birth control methods such as IUD and Depo Shot. As the amount of estrogen increases, so does the risk of blood clots. The IUDs, the birth control shot, and birth control implant do not contain estrogen. Risks for blood clots may also depend on the type of progestin. 

Does progesterone cause blood clots?

Progestin doses used for birth control have not been shown to increase a woman’s risk of deep venous thromobosis nor pulmonary embolism. 

However progestin used in higher doses to treat abnormal bleeding has been shown to increase the risk of blood clots by 5-6 times.

Why does estrogen cause blood clots?

Estrogen, like many other hormones, does not cause blood clots directly. Estrogen increases the risk of getting blood clots in comparison to females who are not on any contraceptives, because it affects the blood factors that cause blood clots.  Specifically, estrogen affects clotting by increasing plasma fibrinogen and coagulation activity in the body that can cause blood clot development.  Thus, it indirectly causes blood clots. 

What is a blood clot?

Coagulation a.k.a. a blood clot happens when a clump of blood turns into a gel or semi-solid state. In blood, platelets and proteins start the clotting process. If done correctly, clotting can prevent too much blood loss during injuries. Clotting is an automatic response from your body during emergencies, and blood clots usually dissolve by themselves. However, when blood clots form where they aren’t needed, treatment may be needed. 

Here is a great resource on the 4 steps of blood clot formation.

Types of Blood Clots and What They Mean

Does Mirena cause blood clots?

TLDR: No. Mirena, a hormonal progesterone only IUD, prevents pregnancy long term. The hormone in the IUD (levonorgestrel) thickens the mucus in the cervix to prevent the sperm from reaching an egg and to also thins the uterus line to suppress ovulation over time. Make sure you tell your doctor if you have experienced abnormal blood clots in the past (in your lungs, leg, heart, brain), pelvic infection, or cancer. This IUD can increase the risk of a clot forming but has 0.3-1% chance of any female getting it when on it for 10+ years, along with other methods. 

What does a blood clot feel like?

In females, clots usually happen in the abdomen (stomach area) and chest (lungs) due to high levels of estrogen or other risk factors such as:

  • Pregnancy and the 1st 6 weeks after having the baby,
  • Personal or family history of blood clots 
  • Obesity
  • Surgery
  • Blood clotting problems like Factor V Leiden, Protein C or S issues.
  • Sitting still like LONG car rides or LONG plane rides. 

Typical blood clot signs are:

  • Soreness in the area that is affected
  • Fast heart rate 
  • Inflammation 
  • Tenderness
  • Throbbing like pain 
  • Shortness of breath (not from exercising)

For more info go to: 

Blood clots can form in different parts of the body and symptoms can be determined based on location.

The following can be hallmark signs of a blood clot: 

  • Tenderness or pain when standing and walking
  • Discoloration of skin
  • Warmth 
  • Inflammation
  • Swelling
  • Trouble breathing
  • Headache 
  • Coughing up blood
  • Sharp pain in abdomen and chest cavity
  • Sweating 
  • Nausea
  • Shoulder or arm pain
  • Dizziness 
  • Fever
  • Weakness 

Can IUD cause blood clots?

Intrauterine devices (IUDs) do not increase the risk of blood clots. IUDs have copper which have no effect on blood clotting or progesterone which has been determined by the CDC to be category 2 = Advantages generally outweigh theoretical or proven risks in someone who has a history of DVT and is at high or low risk of it happening again.

Doctors can easily remove IUDs if you want to get pregnant before they are out of their effective medication (copper or levonorgestrel). 

TLDR: No, it does not affect your chances of getting a blood clot. IUDs have Progestin or no hormones at all. 

Disclaimer: The views expressed in this article intend to inform and induce conversation. They are the views of the author and do not necessarily represent the views of Pandia Health, and are for informational purposes only, even if and to the extent that this article features the advice of physicians and medical practitioners. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis or treatment, and should never be relied upon for specific medical advice.