Yellow Vaginal Discharge During Menstruation: Normal vs. Signs of Infection

Yellowish discharge during menses is often old blood mixing with cervical mucus—normal, especially at cycle start/end. The color comes from hemoglobin breakdown (heme → biliverdin → bilirubin).

See a clinician if discharge is accompanied by:

• Foul odor (fishy = BV; yeasty = candidiasis).
• Vulvovaginal itching, burning, erythema.
• Dysuria, dyspareunia.
• Pelvic pain, fever.
• Green/gray color, frothy texture (trichomoniasis).

Common infectious causes: Bacterial vaginosis (Gardnerella), Vulvovaginal candidiasis, Trichomoniasis, Chlamydia, Gonorrhea. Diagnosis: wet mount, pH, whiff test, NAAT. Treatment is pathogen-specific.

Non-infectious: Cervical polyp, atrophic vaginitis, foreign body (forgotten tampon), reaction to products.