Brown discharge that lasts a full week is almost always old blood leaving the body slowly. When blood moves through the uterus and vaginal canal at a slow pace, it has time to oxidize, turning from red to brown before it exits. A week of this can be completely normal in certain situations, but it can also signal hormonal shifts, a new birth control method, or less commonly, an underlying condition worth investigating.
Why Discharge Turns Brown
The color itself isn’t a separate substance. It’s blood that has aged. When blood leaves the body quickly, it looks red. When the flow is minimal or sluggish, the blood sits longer in the uterus or vaginal canal, reacts with oxygen, and darkens to a brown or even near-black shade. Think of it the same way a cut on your skin scabs over and darkens. The brown color on its own isn’t dangerous; it just tells you the bleeding is slow.
Old Period Blood Taking Its Time
The most common explanation for a week of brown discharge is that your uterus is finishing what your period started. Not all of the uterine lining sheds evenly during menstruation. Small amounts can linger and trickle out over the following days, appearing as brown spotting rather than a true flow. This is especially likely if the brown discharge started right after your period seemed to end.
Some cycles are simply slower to clear out than others. Lighter periods, in particular, tend to produce more brown discharge because there’s less volume pushing everything out. If this happens once or occasionally, it’s rarely a concern.
Hormonal Birth Control and Breakthrough Bleeding
If you use hormonal contraception, brown spotting for a week is one of the most predictable side effects, particularly with low-dose pills, the implant, and hormonal IUDs. The hormones thin your uterine lining, and small amounts of that thinned lining can shed unpredictably, showing up as brown discharge rather than a real period.
With hormonal IUDs, irregular spotting and bleeding are common in the first few months after placement and typically improve within two to six months. The implant works a bit differently: whatever bleeding pattern you develop in the first three months tends to be the pattern you’ll have going forward. If you recently started, switched, or missed doses of any hormonal method, a week of brown discharge is a likely side effect and not a sign something is wrong.
Hormonal Shifts Beyond Birth Control
Your body’s own hormone levels don’t stay perfectly consistent from cycle to cycle. Progesterone is the hormone responsible for building up and maintaining the uterine lining each month. When progesterone drops at the end of a cycle, the lining breaks down and your period starts. But if progesterone is lower than usual, or fluctuates unpredictably, the lining may shed in small, irregular amounts rather than all at once. This can produce days of brown spotting instead of a clean start-and-stop period.
Low progesterone can stem from stress, significant weight changes, thyroid problems, or simply a cycle where ovulation didn’t happen. Skipping ovulation is surprisingly common and doesn’t always mean something is wrong, though repeated anovulatory cycles are worth discussing with a provider. An underactive thyroid is another known cause of irregular bleeding and spotting between periods.
Perimenopause
If you’re in your late 30s or 40s, hormonal shifts associated with perimenopause become a leading explanation. Fluctuating estrogen and progesterone levels mean cycles become less predictable, and brown spotting between periods gets more common. Perimenopause also increases the risk of developing polyps and other endometrial conditions that can cause irregular bleeding. Spotting between periods, periods closer together than every 21 days, or bleeding lasting more than 10 days are all worth bringing up with a healthcare provider during this stage of life.
Infections and Inflammation
Infections of the cervix or uterus can cause tissue irritation that leads to slow, low-volume bleeding, which then exits as brown discharge. Pelvic inflammatory disease, a condition where bacteria (often from an untreated STI) infect the reproductive organs, can cause unusual or heavy discharge that may also have an unpleasant smell. Bacterial vaginosis and cervicitis are other possible culprits.
The key difference between infection-related brown discharge and hormonal causes is the company it keeps. If you’re also experiencing pain in the lower abdomen, a fever, discharge with a strong or foul odor, burning during urination, or pain during sex, an infection is more likely. Brown discharge alone, without these additional symptoms, is less likely to point to an infection.
Cervical Polyps and Fibroids
Cervical polyps are small, smooth growths on the surface of the cervix or inside the cervical canal. They bleed easily, sometimes from something as simple as sex or a pelvic exam, and that small amount of blood often shows up as brown discharge hours or days later. Polyps can also cause bleeding between periods and heavier-than-usual periods. They’re caused by chronic inflammation, infections, or hormonal changes, and they’re almost always benign.
Uterine fibroids, which are noncancerous growths in or on the uterus, can produce similar symptoms. Both polyps and fibroids can cause persistent low-level bleeding that lasts days or recurs throughout the month, making them a plausible explanation for a full week of brown discharge that doesn’t seem connected to your period.
Pregnancy-Related Causes
Brown spotting can be one of the earliest signs of pregnancy. When a fertilized egg implants in the uterine lining, it can cause a small amount of bleeding known as implantation bleeding. This typically happens around 10 to 14 days after conception and is usually light and brief, but some people notice it lasting several days.
More concerning pregnancy-related causes include ectopic pregnancy, where a fertilized egg implants outside the uterus, and early miscarriage. Both can produce brown or dark discharge. If there’s any chance you could be pregnant, a pregnancy test is a reasonable first step before looking at other explanations.
What a Doctor Will Check
If brown discharge lasts a week and isn’t clearly tied to your period ending or a known birth control side effect, a provider will typically start with a pelvic exam and a few targeted tests. A complete blood count checks for anemia (from ongoing blood loss) and signs of infection. Pregnancy tests and STI screening are standard. Depending on your age and symptoms, you may also have a transvaginal ultrasound, which uses sound waves to image your uterus, ovaries, and cervix to look for polyps, fibroids, or other structural causes.
If the ultrasound raises questions, two more specific procedures may follow. A hysteroscopy involves a thin, lighted scope inserted through the cervix to directly view the inside of the uterus. An endometrial biopsy takes a small tissue sample from the uterine lining to check for abnormal cells. These are typically recommended based on age, risk factors, and how long the irregular bleeding has been going on, not after a single episode.
Patterns That Deserve Attention
A single week of brown discharge, especially right after a period or in the first few months of new birth control, is common and usually resolves on its own. But certain patterns suggest something beyond normal variation. Brown discharge that recurs month after month outside your period, discharge accompanied by pelvic pain or a foul smell, bleeding after sex that happens repeatedly, and any vaginal bleeding after menopause all warrant a medical evaluation. The same applies if you’re soaking through pads or tampons alongside the brown spotting, or if your periods are consistently coming fewer than 21 days apart.