A woman's vagina and cervix normally produce a small amount of mucoid fluid, or discharge, that appears clear to slightly white. Brown or reddish-brown discharge, commonly referred to as spotting, usually indicates the presence of blood in the fluid. In many cases, this doesn't signal a significant medical problem. Depending on individual circumstances, however, brown vaginal discharge might indicate a health issue that requires medical evaluation and treatment.
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Hormones and The Menstrual Cycle
Hormone fluctuations related to your menstrual cycle can sometimes cause brownish spotting. For example, a dip in blood estrogen at the time of ovulation can cause mid-cycle spotting in some women. Irregular bleeding and spotting also occur with anovulatory cycles, meaning those in which the ovary fails to release an egg. Anovulatory cycles occur commonly in young women when they first start menstruating and in older women who are approaching menopause. Women with polycystic ovary syndrome (PCOS) also commonly experience irregular bleeding and spotting due to anovulatory cycles.
Women on hormonal birth control can also experience a small amount of uterine bleeding, called breakthrough bleeding, that manifests as brown vaginal discharge. This most frequently occurs in women on depot shots, low-dose pills or progestin-only pills. Hormonal IUD (Mirena, Skyla) users can also experience spotting, especially during the first few months of use. Additionally, an overactive or underactive thyroid gland can cause an imbalance in female hormone levels, leading to irregular bleeding and spotting.
Infections and Sexual Causes
Reproductive tract infections can sometimes cause light bleeding that leads to brown discharge. Examples include internal genital warts, gonorrhea and chlamydia. However, it’s important to note that these infections often cause no symptoms. Minor vaginal abrasions caused by sexual activity might also cause a small amount of brownish spotting, especially in women with vaginal dryness. A harmless condition called cervical ectropion can also cause minor bleeding or brown discharge, commonly after intercourse. With this condition, the fragile tissue normally confined to the interior of the cervix extends to the outer surface, where it might be irritated during intercourse.
Other Reproductive System Causes
Brown discharge after a period might be due to a forgotten tampon, which should be removed as soon as possible to prevent infection. Spotting or brown discharge around the time of an expected period might signal normal implantation of a pregnancy in the uterus, particularly in sexually active women who are not using birth control. While implantation spotting is normal, brown discharge or bleeding during the course of a pregnancy might signal a problem, such as an impending miscarriage, premature labor or a placental abnormality.
Spotting or irregular bleeding can also occur with reproductive tract growths, such as noncancerous fibroids or polyps. Precancerous cervical or uterine growths, and cancer of the uterus, cervix, vagina or ovary can also sometimes cause bleeding or brown spotting. However, some women experience no symptoms with these cancers, especially in the early stages.
Other Medical Causes
Brown vaginal discharge or spotting can occur in menstruating women with a bleeding disorder or on blood thinners, such as warfarin (Coumadin), clopidogrel (Plavix), dabigatran (Pradaxa), apixaban (Eliquis) or rivaroxaban (Xarelto). The breast cancer drug tamoxifen (Nolvadex) might also cause irregular bleeding or spotting. Rarely, leukemia can lead to bleeding due to a low number of platelets, which aid in blood clotting. Other serious medical conditions, such as cirrhosis of the liver or chronic kidney failure, can also lead to irregular bleeding and spotting due to hormone imbalances.
Warnings and Precautions
While occasional brown vaginal discharge may not indicate a medical problem, it’s best to see your doctor to be sure it is not due to a potentially serious condition. See your healthcare provider right away if you have a retained tampon that you cannot remove on your own, or suspect you might have an infection. Also seek urgent medical care if you are pregnant and experience spotting or bleeding. Spotting or bleeding after menopause requires medical evaluation as soon as possible to rule out the possibility of cancer.
Reviewed and revised by: Tina M. St. John, M.D.