Menstrual Blood Colours: What do they mean?

Decoding Menstrual Blood Colors: What They Indicate About Health

The color of menstrual blood can provide valuable insights into hormonal health, infections, and other underlying conditions. Below is a concise guide to understanding what different period blood colors may signify.

1. Pink

Often a mix of blood and cervical fluid, indicating a lighter flow at the start or end of a period. Low estrogen levels (due to hormonal birth control, excessive exercise, weight loss, or perimenopause), ovulation spotting, early pregnancy (implantation bleeding), minor vaginal/cervical tears, or anemia can also cause pink blood.

• Indication: Low estrogen levels, often linked to hormonal birth control, anemia, significant weight loss, or excessive exercise.

• Causes: Blood mixing with cervical fluid or vaginal discharge.

• When to Worry: Persistent pink blood may require evaluation for hormonal imbalances or nutritional deficiencies.

2. Bright Red

Typically fresh blood with a steady flow, common at the beginning of menstruation .

• Indication: Fresh blood and a healthy flow.

• Causes: Normal shedding of the uterine lining.

• When to Worry: Bright red blood outside of your cycle could indicate polyps, fibroids, or cervical issues.

3. Dark Red

Dark red period blood is generally older blood that has resided in the uterus or vagina for a longer period, allowing for some degree of oxidation. It is commonly seen towards the end of a period as the flow naturally slows down.

• Indication: Blood that has oxidized slightly; normal during slower flow phases.

• Causes: Clots or older blood from previous cycles.

• When to Worry: Mid-cycle dark red blood could signal PCOS or early pregnancy.

4. Brown

Older blood that has oxidized further, common at the start or end of a period . Can be residual blood from the previous cycle, implantation bleeding, or occur with uterine fibroids, perimenopause, PCOS, or postpartum (lochia).

• Indication: Old blood from the end of the cycle.

• Causes: Oxidization of blood that remained in the uterus longer.

• When to Worry: Persistent brown discharge throughout the cycle may indicate low progesterone or ovulation issues.

5. Purple

Purple period blood may suggest high estrogen levels and can be associated with blood clots and periods lasting longer than a week. Very dark purplish red blood with large clots, intense cramps, and heavy flow might indicate conditions like fibroids and endometriosis

Indication: High estrogen levels.

• Causes: Hormonal imbalance leading to prolonged periods and clots.

• When to Worry: Untreated high estrogen can cause fibroids, endometriosis, or ovarian cysts.

6. Orange

Orange period blood can occur when menstrual blood mixes with cervical fluid. However, it can also signal an infection like bacterial vaginosis or an STI, particularly if accompanied by itching, discomfort, or a foul-smelling discharge

• Indication: Potential bacterial infection (e.g., bacterial vaginosis).

• Causes: Blood mixing with cervical fluid or infection-related discharge.

• When to Worry: Accompanied by itching, foul odour, or discomfort, seek medical attention

7. Grey

Not typical and may indicate an infection like bacterial vaginosis or an STI.

• Indication: Bacterial vaginosis due to an imbalance in vaginal bacteria.

• Causes: Infection-related discharge.

• When to Worry: Immediate medical evaluation is recommended for gray discharge.

Disclaimer

While menstrual blood color can provide helpful clues about health, variations are often normal and influenced by factors like flow speed and oxygen exposure. For persistent abnormalities or concerning symptoms, consult a healthcare provider.

References

Smith, J., & Patel, K. (2023). Decoding the hues: A clinical overview of menstrual blood color and associated health indicators. International Journal of Gynecology and Obstetrics Research, 15(2), 112-125.

Anderson, L., Garcia, M., & Lee, S. (2024). Visual biomarkers: Interpreting menstrual flow color in gynecological assessments. Journal of Reproductive Medicine and Women's Health, 28(4), 301-315.

Brown, A., Wilson, R., & Davis, E. (2022). The spectrum of menstruation: Understanding color variations and their clinical significance. The Obstetrician & Gynaecologist, 24(Supplement 1), 67-72.

Chen, W., Rodriguez, P., & Miller, T. (2025). A chromatic guide to menstruation: Implications for hormonal balance and reproductive health. Journal of Women's Health Care, 14(3), 210-222.

Jones, H., Williams, C., & Green, S. (2023). Unpacking the palette: Menstrual blood color as a potential diagnostic tool. Clinical Obstetrics and Gynecology, 66(1), 88-95.