Noticing an unexpected color change in menstrual flow can be alarming, especially when the shade is far outside the typical spectrum of red and brown. While the consistency and color of menstrual blood naturally fluctuate, a shift to green signals that something unusual is occurring. Green is almost never derived from normal menstrual blood itself but rather from discharge mixed with blood or tissue. This unusual presentation warrants prompt attention to determine the underlying cause.
Understanding Normal Menstrual Flow Colors
Menstrual flow is composed of blood, tissue, and mucus, and its color naturally changes depending on the rate of flow and how long the blood has been exposed to air. When the flow is heavy and fresh, the blood is typically a bright, vibrant red, indicating it has quickly exited the body. As the flow slows, the blood spends more time in the uterus and vagina, which causes it to react with oxygen, a process known as oxidation.
Oxidation darkens the blood, resulting in shades of dark red, brown, or even black, which are considered normal, particularly toward the beginning or end of the cycle. Light pink flow occurs when blood mixes with clear cervical fluid, often seen during lighter spotting. These variations reflect the natural mechanics of the menstrual cycle.
Medical Conditions Causing Green Discharge
The presence of green in what appears to be period blood is highly suggestive of an underlying infection or inflammation, where the color comes from infected discharge mixing with the menstrual fluid. The greenish hue is often caused by a high concentration of leukocytes, which are white blood cells the immune system sends to fight off pathogens, creating what is commonly known as pus.
A common cause is a sexually transmitted infection, such as trichomoniasis, which can produce a frothy, green or yellowish-green discharge, often accompanied by a fishy odor. Other STIs like gonorrhea and chlamydia can also lead to greenish-yellow discharge, sometimes alongside symptoms like pelvic pain or bleeding between periods.
Bacterial vaginosis (BV), resulting from an imbalance of the vagina’s natural bacteria, most frequently produces gray or off-white discharge but can occasionally present with a greenish tint. This is typically accompanied by a strong, unpleasant odor. Untreated infections can progress to pelvic inflammatory disease (PID), a serious complication associated with unusual discharge and severe pelvic pain.
Another cause for this abnormal color is a foreign object retained in the vagina, which creates a breeding ground for infection. This may include a forgotten tampon, a piece of a barrier contraceptive, or a complication related to an intrauterine device (IUD). The resulting infection leads to a foul-smelling, green or grayish-green discharge due to the localized inflammatory response.
When to Seek Professional Medical Care
The appearance of green discharge, whether mixed with blood or not, is considered abnormal and indicates you should consult a healthcare provider. Self-treating or waiting for the color to revert to normal is not recommended, as the underlying cause often requires prescription medication, such as antibiotics. Prompt diagnosis and treatment are important to prevent the progression of infection and avoid long-term complications.
Seek medical evaluation immediately if the green discharge is accompanied by other concerning symptoms. These indicators include a strong, foul, or fishy odor distinctly different from your usual scent. Severe pelvic pain, fever, chills, or a burning sensation during urination or intercourse require urgent professional attention.