Menstrual Cycles and Anticoagulants: What’s Normal?

If you are a woman, one of the first questions you might have after starting blood thinners may be, “Should my menstrual cycle be this heavy while taking anticoagulants?” It was one of the first things I worried about after I was discharged from the hospital on low molecular weight heparin blood thinning injections several years ago. I worried – a lot – and wondered if it would be a major issue for me, especially since I had already struggled with uncomfortable periods for as long as I could remember. My periods were a little heavier, but nothing that made me worry, or think something was wrong. I had more frequent and slightly heavier periods for several months, but eventually my cycle returned to what was normal for me. Once I transitioned successfully to the oral anticoagulant warfarin, my periods stayed the same. A little unpredictable, but mostly manageable. They were occasionally longer or heavier, or I would occasionally have two shorter cycles in a month, but nothing was overly concerning for me or my doctors.

About five years after my blood clot, I had a period that was not normal for me. It arrived at the regular time, but it started out a lot heavier than usual. My first thought was, “Good. I’ll get it all out of the way in a day or two. I began to grow more and more concerned as the third day of my cycle arrived, and the bleeding worsened. By that time, I was going through a 10-hour pad in less than hour, and I was soaking through my clothes. It was a weekend – which is when all of my issues seem to happen, blood clots included – and I thought, “Since it’s my period, I’ll wait until Monday and call my gynecologist.”

It got worse as the weekend went on, so I called my gynecologist’s office. Most gynecologists have an on-call physician for pregnant patients who go into labor and delivery, so I was relieved to hear a messaging service answer where I could leave my number and have an on-call physician call me back. A doctor at from my gynecologist’s office called me back in about 10 minutes and asked me what was going on, so I explained my situation. The doctor was alarmed, even though I was very clear that I was taking the blood thinner warfarin. He instructed me to go immediately to the emergency room, which I did, now completely panicked about my situation.

At the hospital, I saw a number of doctors who ran and performed numerous tests to determine whether I was bleeding internally from my abdomen or from my uterus. After several hours, and a lot of uncomfortable evaluations, it was determined that I had uncontrolled uterine bleeding. In my case, it was a period that wasn’t stopping. The cause was an INR level that was way too high, which I did not know about. I needed a reversal treatment (oral vitamin K in this situation), to help bring my INR back into a safe range. I am very fortunate that I did not need a blood transfusion or need to be admitted. The ER staff told me repeatedly that it was very good I came in when I did, instead of waiting until Monday, because the bleeding may not have stopped on its own.

It took several weeks of medication adjustments, blood draws, and ultimately bridging with injections to stabilize my INR. While it was a very scary experience for me – and one that has also taken me some time to think about sharing here – it is an experience that I take very seriously. I learned a lot about my body and what not to assume. If I ever have bleeding like that again, I will not assume it is my period, because I know now that something could be seriously wrong.

If you have heavy periods on blood thinners, at least have one conversation with your doctor, before ending up in a situation that requires emergency room visits and emergency interventions to resolve.

FAQ: What You Need to Know About Periods and Blood Thinners

Below is a list of frequently asked questions about menstrual cycles and blood thinners. These are questions that I have asked myself, and that I hear a lot. What is the bottom line? If you have a heavy period on blood thinners, please talk to your doctor.

Q: Since I am on blood thinners, I can expect a heavier period, right?

A: Like so many things when dealing with blood clots and blood clot recovery, it depends on the individual situation. Not every woman has a heavy cycle on blood thinners, so if you do, you need to discuss it with your doctor to find out if it is normal or not. A possible side effect of the newer oral anticoagulants are heavier periods, so if you take those medications, talk to your doctor about your concerns and what to expect. It is important to make sure nothing else is wrong, or going on, as well as to find a solution for managing heavy periods.

Q: What kind of doctor should I discuss my heavy periods with?

A: It is probably best to involve two doctors, or specialists, in your care when discussing your menstrual cycle: The doctor who prescribes your anticoagulant (for me it is my hematologist) and your gynecologist. If you do not have a gynecologist, you can find one with this search tool: The American College of Obstetricians and Gynecologists.

Q: My doctor(s) said to expect heavier bleeding on blood thinners, so do I need to worry if I am bleeding a lot?

A: Don’t assume heavy bleeding is normal, especially since it could be dangerous and have dangerous consequences, such as blood loss or anemia. If you have heavy bleeding, you need to go to the emergency room, or hospital, to be evaluated. The U.S. Centers for Disease Control and Prevention (CDC) defines heavy bleeding as: 1) needing to change your pad or tampon after less than two hours, or 2) you pass clots the size of a quarter or larger. Read more about heavy periods, also known as menorrhagia, from the CDC: Heavy Menstrual Bleeding.

Q: During that time of the month, can I just skip taking my blood thinners?

A: No, not without speaking to your doctor. Heavy periods are usually not a reason to stop taking your blood thinner. Stopping your medication – even for a day or two – could be dangerous and result in a repeat clotting event. Not taking medication as prescribed is the most common cause of blood clot recurrence. Please do not ever stop your blood thinner without consulting with your doctor first. While some women may be given instructions to reduce or stop their blood thinner during the heaviest days of their menstrual cycles, this direction must only be given my the advice of a medical professional.

Q: Birth control helped with my periods, and now I can’t take it because of blood clots. What options do I have?

A: Birth control with estrogen is a risk factor for blood clots, and many women are advised to stop taking birth control with estrogen after a blood clot. However, many women have options without estrogen for birth control that may also help with heavy periods, especially if they are continuing to take an anticoagulant. More information about these options can be found here: Birth Control and Blood Clots. Other options to help manage a heavy period may include: pads or tampons, menstrual underwear or menstrual cups. We’re all different, and what works for one woman may not be an option for the next woman. Some women may, along with their physician, consider various surgical procedures to help address significant menstrual bleeding, such as a endometrial ablation or hysterectomy.

It can be difficult to manage a heavy menstrual cycle on anticoagulants, and for many women, it can be uncomfortable to talk about, but it is really important. Not only can an unusually heavy cycle be dangerous to your health, it can be damaging for your self-esteem. It can even effect work and social commitments. If you are experiencing a heavy period while taking anticoagulants, talk to your doctor about your concerns, and your options.

There is hope for healing and you are not alone,

Reader Writes In: Journal your thoughts, or share in the comments below. Have you experienced heavier periods since starting anticoagulants?

Read More: Women’s Issues and Blood Clots


  1. I have heavy periods and have had them since I’ve been on xarelto for clots. I have a gyn who administered a Mirena IUD since the hormones are contained in the uterus and don’t flow through the body to cause clots. That worked for a while, but I’ve gotten heavy breakthrough periods for which I get a depo provera shot, which lasts 3 months. Because I go anemic due to blood loss, the clot risk from the shot is considered a lower health risk than the anemia. When I have spotting, which is often, I’ve learned to check myself with an oximeter. When my oxygen levels are low, I know my red blood cell count is as well. Edema is a side effect of anemia, so your blood contains more water than it should. Everyone is different, but in my blood counts I’d also found low levels of other things. So I take a vitamin c supplement as this helps raise levels of how well your blood carries oxygen and nutrients. I’m about 3 years out from multiple PEs. I had filled diva cup after diva cup. Something needed to be done. Please talk to doctors and if you’re not finding solutions, find another. I didn’t have a lot of info available. They’d diagnosed me as APS.

  2. I was on a continuous low dose estrogen/progesterone birth control pill to manage my endometriosis for years. Now that I have had a PE my Hemotologist said no more OCs. I got so used to having only the occasional cycle, so having them in a more “timely” manner is definitely different and I closely track them on my calendar hoping to see a trend so I know what is normal again.
    The real challenge is now going to be what to do about my endometriosis. I see a new Gyn at the end of this month, so I am hopeful she will have some good solutions for me. I’m still nervous about what she will say. My PCP who is a FCNP is very hands off about this topic, so I have no indication as to what the potential options I might be presented with.

  3. I experienced HMB so my doctor referred me to a gynecologist.
    So grateful for this site. It allowed me to ask the right questions, to ascertain if my “Menorrhagia” would be taken seriously and with urgency, and to make an educated decision with my gynecologist who will work with my doctor as we opted for endometrial ablation, But, it also became very apparent that my gynecologist is well versed in HMB related to Xarelto.

  4. Krystle Holt says

    I am on Xarelto for blood clots as well and this i have had two cycles since being on it. I already suffer from very painful heavy cycles. And yes i am worried a little bit about my cycles getting worse the older I get and longer im on blood thinners. It amazes me how in one instance blood thinners safe your life and in another if u are not care especially if you are a woman blood thinners could get very dangerous.

    • Danielle Goodwin says

      I am on Xarelto/Rivaroxaban. I had 3 P.Es in 2016 at 22 weeks pregnant, I was on Enoxaparin but discontinued treatment 3 months after birth. I then had spontaneous P.Es January 2020, both times were severe resulting in life support in intensive care. Anyway 6 weeks later I’m on my period, since taking Xarelto, and I’ve been bleeding for 8 days, passing large clots and bleeding heavily, I’m using babies nappies in my underwear because pads are soaking through, I’ve seen my GP and they prescribed tranexamic acid but they come with a risk of clotting so I don’t know what to really do. I keep feeling unwell, tired and faint with the heavy bleeding, I think if it gets any worse I’ll be going to the hospital. Which I really don’t want to do but I may have no choice.

  5. Dee Patrick says

    I got a blood clot that started in my leg then went to my lung december 2019. I was actually on my cycle when it happened. So you can imagine my reaction when I first had my cycle after taking xarelto. I was scared! I went to see my doctor the next day and was like this is not normal. I had to take the xarelto even though I was bleeding horribly. I got blood work done and my blood level was a 11. Next month comes and the same thing happens. Worse than the first month but it only lasted 7 days, the first month it lasted 8 days. I go back to the doctor. I get a common cold with a cough and runny nose and I notice when I just walk my head feels like it’s beating out of my chest. I didn’t know if this was coming from the blood clot. I went to see the hematologist this week and my blood count went from an 11 to 8. This explained all of my symptoms. So now he wants me to go get a iron transfusion and to see a gynecologist that’s specializes in women on blood thinners.

    • Nicole RS says

      Wow , I swear you just told my story. The same thing happened to me on April 21st. Clott from leg to lungs, etc. I was in my period when it happened. I’m on xarelto from it and my iron is low. . I did have a stroke with that because of a small hole in my heart. I’m 42 and I’m concerned because my period is here for the first time and it’s overwhelming. I just couldn’t get over the parallels in our stories. I’m just scared to go in to be seen . I
      Thinking about calling my doctor just to see what he says . I feel like I’m getting into my head by knowing I’m bleeding more than normal and so what My symptoms should be , I’m experiencing. Is my pad getting soaked? Yes and I’m concerned. What can happen?

  6. I’m on blood thinners and have been for over a month. I had very heavy periods prior which caused very low iron. After doing an ultra sound they found fibroids which was Casio g the heavy bleeding so they put me on fibrastol which is a medication that treats the fibroids but I’ve missed my period. I’m 3 weeks late. I know I’m not pregnant. My tubes are tied. Should I be worried not getting my weird and being on blood thinners?

    • This is me now; small blood clot in my leg, they put me on XARELTO. I usually have heavy periods and every 3 to 3 1/2 weeks. I haven’t had my period in 5 weeks and wondering can blood thinners actually stop my period?

  7. Jennifer says

    I’m am also on xarelto b cuz of a pulmonary embolism….it and mad emy leriods heavier and more painful ..I thought they were bad 4 but this is crazy….but I’ve been kinda able…except this month its been the worst ever I can use a super tmap ok ms and a heavy flow pad and bleed thru both in matter of minutes :(… and I have so many clots ots crazy and they re so big it’s on the 10th day now and the clots seems to get bigger as the days progress 🙁 ….

  8. I have 2 venus stints in my abdomen and have been on clopidogrel for 3 years. This caused periods that last for months. My OB put me on the depo to stop periods but after a year and a half I started having breakthrough bleeds. I ended up having to change OBs because the Dr I had caused my bleeding to become worse by trying to force me into having my tubes tied and an ablation. This new Dr switched me to Mirena and I’ve had a period for almost 8 months now. I’ve taken 2 rounds of tranexamic acid to try to stop the bleeding with no success. I have to take iron to help keep my levels up but the bleeding is showing no signs of stopping. I already have had my clopidogrel and aspirin regimen changed to alternate them every other day and I’m honestly at a loss. I do not want to be sterilized because I would like to eventually have one more kid.

  9. I’m so lucky to have found this forum. I’ve ALWAYS had heavy periods. However 2 weeks ago I developed a blood clot in my right leg and was put on Xarelto 15mg 2xs daily. Three days later I get my period and was soaking through a 10hr pad in less than an hour. I ended up in ER and had to be admitted since my hemoglobin was very low and I was anemic. After staying in the hospitals for 4 days and having 3 blood transfusions and an iron fusion I was finally discharged. The hematologist lowered my dosage to just 15 mg once a day. My blood test d-dimer (tells you if you’re prone to blood clots) is lower now than what it was in the hospital. I’m scheduled to have an ablation in 2wks and hope that that will help with the heavy bleeding. I will follow up with the hematologist afterwards and see if I need to still be on the blood thinners. Hoping not and that the blood clot was just a freaky thing. I still have my period..going on day my 11th day if my period…when I wasn’t on blood thinners it would end by the 7th day! Best of luck to everyone and what I’ve learned from all this is to listen to our bodies and tell the dr when something doesn’t seem right.

    • Mandy Hardy says

      Linda, I just went today to my OBGYN and inquired about an ablation. I have been on 20mg of Xarelto for almost 3 years now and my periods are awful!! I have had 2 iron infusions over the course of 2 months. Has having an ablation helped with your periods?

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