Blood in your discharge between periods is common and usually caused by something harmless, like hormonal shifts or birth control. But it can also signal an infection, a structural issue like a polyp, or in some cases, something that needs prompt attention like a pregnancy complication. The cause depends a lot on your age, whether you’re on contraception, and what other symptoms you’re experiencing.
Hormonal Shifts and Ovulation Spotting
The most common reason for a small amount of blood in your discharge is a normal hormonal fluctuation. Around the middle of your cycle, your body releases an egg. Estrogen drops briefly right after ovulation, and for some people, that dip is enough to cause a small amount of the uterine lining to shed. This shows up as light pink or brownish discharge, typically around day 14 of a 28-day cycle (or roughly halfway between your periods). It’s minor, resolves on its own, and doesn’t indicate a problem.
Stress and thyroid issues can also throw your hormones off enough to cause spotting between periods. An underactive thyroid, in particular, disrupts the regular rise and fall of hormones that keep your cycle predictable.
Birth Control Is a Frequent Culprit
Hormonal contraceptives are one of the most common causes of unexpected bloody discharge. This is called breakthrough bleeding, and it happens more often with low-dose birth control pills, the implant, and hormonal IUDs. If you recently started a new method or have been taking pills inconsistently (skipping doses, stopping and restarting), spotting is a predictable side effect.
With a hormonal IUD, spotting and irregular bleeding in the first few months after placement is typical and usually improves within two to six months. The implant works differently: whatever bleeding pattern you develop in the first three months tends to be the pattern you’ll have going forward. So if you’re still spotting after that initial window, it’s worth discussing alternatives with your provider.
Infections That Cause Bloody Discharge
Sexually transmitted infections, particularly chlamydia and gonorrhea, can cause blood in your discharge. Gonorrhea often produces a thick, cloudy, or bloody discharge. Chlamydia can cause bleeding between periods, sometimes with no other obvious symptoms. Both infections can also lead to pelvic inflammatory disease if left untreated, which involves inflammation spreading to the uterus and surrounding tissues.
Cervicitis (inflammation of the cervix) from infections or irritation is another common cause. It can make the cervix more fragile and prone to bleeding, especially after sex. If your bloody discharge comes with unusual odor, pelvic pain, or pain during sex, an infection is worth ruling out with testing.
Bleeding After Sex
If the blood in your discharge tends to show up after intercourse, one likely explanation is cervical ectropion. This happens when the softer, more delicate cells that normally line the inside of your cervix become visible on the outside. These cells are more fragile and bleed easily with contact. Cervical ectropion is especially common in younger people and those on hormonal birth control. It’s not dangerous, but it is the most common cause of discharge that contains blood or mucus along with light bleeding after sex.
Could It Be Pregnancy Related?
If there’s any chance you could be pregnant, blood in your discharge takes on different significance. Implantation bleeding occurs when a fertilized egg attaches to the uterine lining, usually about 10 to 14 days after conception. It looks different from a period: the blood is typically pink or brown (not bright red), very light in flow (it won’t soak a pad), and lasts only a few hours to about two days.
If your bleeding is heavy, bright or dark red, or contains clots, it’s not typical implantation bleeding and could indicate a pregnancy complication like ectopic pregnancy or miscarriage. Any bleeding during a known pregnancy warrants contacting your provider promptly.
Polyps and Fibroids
Uterine polyps are small growths that attach to the inner wall of the uterus. They form when cells in the uterine lining overgrow, and they’re a well-known cause of bleeding between periods, unpredictable spotting, and heavier-than-usual flow. Polyps can develop at any age but become more common as you get older.
Cervical polyps work similarly but grow on the cervix. Both types are usually benign. Fibroids, which are noncancerous muscular growths in the uterine wall, can also cause intermenstrual bleeding depending on their size and location. These structural issues are typically found during a pelvic exam or ultrasound.
Perimenopause and Postmenopause
If you’re in your 40s or early 50s, irregular bleeding and spotting may be related to perimenopause. During this transition, your ovaries produce less estrogen and progesterone, and the predictable hormonal pattern that drives your cycle becomes erratic. Periods may come closer together, further apart, heavier, lighter, or with spotting in between. This phase can last several years before periods stop entirely.
Postmenopausal bleeding is a different situation. Once you’ve gone a full 12 months without a period, any bloody discharge needs evaluation. About 9% of postmenopausal women who see a doctor for bleeding are eventually diagnosed with endometrial cancer, according to a large analysis published by the National Cancer Institute. That means the majority of cases turn out to be something less serious, like vaginal dryness or a polyp, but the risk is high enough that it should never be ignored.
When Bloody Discharge Needs Attention
Some patterns suggest you should get evaluated sooner rather than later. Soaking through a pad or tampon every hour for several consecutive hours is considered heavy bleeding. Bleeding that lasts longer than seven days, spotting that keeps recurring between periods, or bleeding that starts after menopause all fall outside normal ranges. Most providers consider anything other than bleeding for about five days every 21 to 35 days to be worth investigating.
Blood thinners can also cause intermenstrual bleeding, so if you’re taking any medications that affect clotting, that’s important context for your provider. And while cervical or uterine cancer is a less common cause of bloody discharge, it’s the reason persistent or unexplained bleeding gets taken seriously, particularly in people over 40 or after menopause. Early evaluation leads to straightforward answers in most cases, and catches the rare serious cause when it matters most.