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Why is My Period Blood Brown?



5 min read

Thinx Periodical | Why is My Period Blood Brown?

by Team Thinx | 04/05/2023

Thinx Inc - Thinx Tank - Doctors - Dr. Brandi Jones, DO

Medically reviewed by Dr. Brandi Jones, DO

When you’re on your period, you may notice that your period blood doesn’t always look the same. At times, it may be a bright, fire engine red. At others, it may take on more unconventional hues, ranging from black to pink. 

If you’re wondering, “Why is my period blood brown?,” you’re certainly not the first person to ponder this question. Luckily, brown period blood is rarely a cause for concern. In fact, it’s quite common at various points in your cycle. 

Below, we’ll break down the potential explanations for your brown period blood. We’ll also let you know when brown period blood may warrant a trip to your healthcare provider. 

what causes period blood to change colors?

Before we jump into the common causes of brown period blood, let’s discuss the reasons behind why it changes color in the first place. Magic? Well, no. While menstruation is quite a magical process in and of itself, period color changes ultimately come down to science.

Human blood contains hemoglobin, a protein that’s responsible for binding with oxygen and transporting it to your organs and tissues. Hemoglobin contains iron. When this iron is exposed to air, it transforms into iron oxide.

Iron oxide happens to be the same compound that makes up rust. It’s also responsible for turning period blood brown. In this sense, you can think of brown period blood as rusty period blood — just without the need to get a tetanus shot. 

causes of brown period blood

Now that you understand the chemistry behind brown period blood, let’s dive into several occasions when you might encounter it and what gives.

at the tail-end of your period

Whether your period lasts two days or seven days, you may start to notice more brown-tinged blood closer to the end of it. The reason? Blood that leaves your uterus towards the end of your period is older. Therefore, it’s been exposed to more air than the blood that came before it. As a result, it may have more time to oxidize and turn brown.

right before your period

On the flip side, the light flow at the very beginning of your period may be brown too. Wondering, why is my period blood brown on the first day? That’s because it may be much lighter than the flow that’s yet to come. Light menstruation typically travels from the uterus at a slower pace, giving it more time to develop a brown color.

during your period

If you tend to have light periods, you may experience brown period blood throughout them. You may also notice an uptick in brown period blood if you’ve just started using a hormonal contraceptive medication. That’s because some forms of birth control can make your periods lighter. 

between periods

Brown spotting may show up in the middle of your cycle or while you’re taking a form of birth control that stops your menstrual period altogether. In these situations, this brown spotting and breakthrough bleeding may be triggered by a recent:

  1. Pap smear

  2. Vaginal exam

  3. Sexual encounter

  4. Hormonal fluctuations

Alternatively, you can also experience brown spotting while you’re ovulating. Since this bleeding may be quite light, it may also be browner than your regular menstrual period blood. 

The only time spotting between-periods may be a cause for concern is if it lasts more than a few days or if you are experiencing concerning symptoms like heavy bleeding or abdominal pain. If you notice these concerns, you should schedule a visit with your healthcare provider.

while you’re pregnant

Pregnancy is notorious for causing a slew of bodily changes in a matter of weeks. In addition to having strong cravings for pickles or sudden morning sickness, you may also experience light, brown spotting, formally known as implantation bleeding.

Implantation bleeding is triggered by the fertilized egg attaching to the wall of your uterus; it usually takes place 10 to 14 days after conception. While this egg is tiny, it’s mighty enough to disrupt your uterine lining and cause some of it to shed. If you experience brown spotting and suspect that there’s a chance you may be pregnant, you may want to take a test to find out for sure. Once you’re past the first few weeks of pregnancy, brown period blood may be a more concerning issue. For instance, it may indicate an ectopic pregnancy or miscarriage. Before you get too worried, be sure to consult with your OBGYN. They’ll be able to narrow down the cause of your brown period blood during pregnancy with much greater precision. 

after giving birth

If you gave birth recently, congratulations! You’re a true warrior. As with pregnancy, the postpartum stage can come with some unexpected symptoms. For one, you’ll likely experience lochia, which is a four to six-week period. This prolonged period’s color can evolve from week to week. In the beginning, it may be bright red. As time goes on, it may turn yellow or brown.

when should you see a medical professional?

While brown period blood shouldn’t send you into a tizzy, there are some rare occurrences where it may be a symptom of a more serious issue. 

For instance, brown period blood can be associated with:

  1. some sexually transmitted infections (STIs) – Brown vaginal discharge is a symptom of some STIs, such as gonorrhea and chlamydia. Unlike normal brown period blood, brown discharge relating to an STI will often have a foul aroma.  You may also experience other STI symptoms, such as painful or frequent urination, as well as vaginal bleeding between periods. If your brown discharge is due to an STI, don’t fret—a round of antibiotics may be all that’s needed to clear it up.

  2. a lodged object – Accidents happen, and sometimes, those accidents involve forgetting something in your vagina. For example, you may unknowingly leave a tampon, condom, or contraceptive ring up there. Your body can alert you to the situation by producing a smelly, brown discharge.  While you may be able to get the object out on your own, it’s still important to see your healthcare provider. They can determine if you need any treatment for bacterial vaginosis, toxic shock syndrome, or other infections. 

  3. pelvic inflammatory disease (PID) – PID is an infection of the female reproductive system. It can wreak havoc on your cervix, uterus, and fallopian tubes. It’s usually caused by bacteria from STIs. PID can cause abnormal discharge (including brown discharge), as well as irregular periods, pelvic pain, painful sex, fever, nausea, and burning during urination. If left untreated, PID can later lead to infertility.  Luckily, you can prevent the more serious symptoms of PID by taking antibiotics. The sooner you seek treatment, the better.

  4. polycystic ovary syndrome (PCOS) – Around 1 in 10 women or people with female anatomy will develop PCOS at some point during their reproductive years. This syndrome is caused by hormonal imbalances that impact ovulation. People with PCOS may not release an egg each month during their menstrual cycle. The symptoms of PCOS include heavy periods, facial hair, acne, unexplained weight gain, irregular cycles, abnormal discharge (including brown spotting), ovarian cysts, and infertility. While there’s no cure for PCOS, medications and lifestyle changes can help you manage your symptoms.

  5. cervical cancer – Lastly, in very rare cases, brown blood may be a sign of cervical cancer. But before you start doom-scrolling WebMD for other symptoms of cervical cancer, take a deep breath—it’s important to note that cervical cancer makes up a mere 0.7% of all cancer cases. As a result, very few women and people who menstruate ever receive this diagnosis. What’s more, brown periods are just one of the many symptoms that may indicate cervical cancer. It may also be accompanied by bleeding after sex, bleeding after menopause, bleeding between periods, abnormally heavy or long periods, painful sex, painful urination or bowel movements, backaches, and fatigue. If you have these symptoms, it goes without saying that you should schedule an appointment with your healthcare provider.

As you can see, brown period blood color isn’t a tell-tale sign of any of these conditions, but it can be one of many that may encourage you to seek medical evaluation. 

what color should period blood be?

So, should you be worried about dark brown discharge instead of period blood? When it comes down to it, menstrual blood can come in many colors. While classic red is the most common, brown is another shade that’s generally considered normal. Dark red blood, on the other hand, may contain blood clots, signifying blood that has stayed in the vaginal area for an extended period. Usually, clotting is considered normal unless the clots are larger than the size of a quarter.

In addition to red and brown, vaginal discharge can be pink, black, clear, white, yellow, or even a Dr. Seuss-esque green at times. Some of these colors may indicate an infection, while others are natural components of a healthy menstrual cycle.

Either way, the colors of your menstrual blood can give you invaluable insights into your menstrual health, so it’s worth checking them out anytime you replace your menstrual products.

enjoy comfier periods with Thinx

Switching out menstrual products can be a hassle, no matter the period blood color. If you’re sick and tired of tampons, pads, and menstrual cups, Thinx period underwear can provide you with more convenient, eco-friendly protection.

Our period underwear is comfortable, absorbent, and machine-washable. We carry a variety of styles, ranging from panty-line-proof Thong to adorable Boyshort. Better yet, you can select the absorbency of your period underwear so it suits your flow from day to day.

Are you ready to revolutionize your periods? Snag a pair of Thinx period underwear today.

At Thinx, we strive to provide our readers with the most up-to-date, objective, and research-based information. Our content is crafted by experienced contributors who ground their work in research and data. All information has been fact-checked and extensively reviewed by our team of medical professionals to ensure content is accurate. Articles contain trusted third-party sources that are either directly linked within the text or listed at the bottom to lead readers to the original source.


Mayo Clinic. Hemoglobin test.

NIH. What are the treatment options for heavy periods?

Cleveland Clinic. Ovulation.

American Pregnancy Association. What is Implantation Bleeding?

Mayo Clinic. Ectopic pregnancy.

Cleveland Clinic. Lochia.

American College of Obstetrics and Gynecologists. Chlamydia, Gonorrhea, and Syphilis.

Cleveland Clinic. Can a Tampon Get Stuck? Here’s How To Remove It.

Cleveland Clinic. Pelvic Inflammatory Disease.

U.S. Department of Health & Human Services. Polycystic ovary syndrome.

NIH. Cancer Stat Facts: Cervical Cancer.

National Cancer Institute. Cervical Cancer Symptoms.

Cleveland Clinic. Vaginal Discharge Color: What’s Normal and What Isn’t.

by Team Thinx

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