Common causes

• It is the most common cause of vulvar itching. It is usually caused by Candida albicans (Schwartz's Principles of Surgery, 11th Ed, "Vaginal Lesions").
• Typical features are a thick white discharge, redness, itching, and pain with intercourse. The vaginal pH is normal (<4.5). Discharge and odor may be minimal (Schwartz's Principles of Surgery, Table 41-2; Harrison's Principles of Internal Medicine, 22nd Ed, "Vulvovaginal Pruritus, Burning, or Irritation").
• Risk factors include diabetes, recent antibiotics, and pregnancy. Intercourse can trigger or aggravate symptoms.

• The main features are a thin gray-white discharge and a fishy odor, which is often worse after sex. The pH is >4.5 and clue cells are seen on microscopy.
• Itching is usually less prominent than with yeast.
• Risk factors include recent unprotected intercourse, a new partner, and douching (Harrison's, "Bacterial Vaginosis").

• It causes a profuse, yellow-green, frothy discharge with vulvar irritation and pain with sex. The pH is ≥5 (Harrison's, "Vaginal Trichomoniasis").
• Your partner needs treatment too.

• Genital herpes can cause itching, burning, or sores. Chlamydia and gonorrhea often cause no symptoms (Harrison's, "Vaginal Discharge").

• Allergy or irritation from latex condoms, spermicide, lubricants, scented soaps, wipes, or detergents. A reaction to semen is rare.
• Friction or micro-tears from insufficient lubrication. This is more likely with low estrogen (breastfeeding, perimenopause, menopause).
• Skin conditions such as lichen sclerosus and eczema.
• Noninfectious causes can mimic an infection, with itching, redness, swelling, and discharge (Swanson's Family Medicine Review).

What helps you tell them apart

What to do

• Avoid self-treating without a diagnosis. If you've had yeast infections diagnosed before and the symptoms match, an over-the-counter antifungal is reasonable. If it doesn't clear in a few days, or you aren't sure, get tested. Treating the wrong condition delays the right treatment.
• Get examined if you have any of the following:
  • a new partner or unprotected sex
  • abnormal or foul-smelling discharge
  • sores, blisters, or pelvic pain
  • fever
  • symptoms that recur or persist
  • pregnancy
• Testing is usually a pelvic exam, vaginal pH, and microscopy. Chlamydia, gonorrhea, and trichomonas testing is added if you're at risk.
• Typical treatments (Schwartz's, Table 41-2):
  • Yeast: fluconazole 150 mg once, or a vaginal antifungal.
  • BV: metronidazole 500 mg twice daily for 7 days, or metronidazole or clindamycin vaginal cream.
  • Trichomonas: metronidazole (a 7-day course is preferred over the single 2 g dose), with partner treatment (Harrison's).
• In the meantime:
  • Use fragrance-free soap and no douching.
  • Try a different condom type, such as polyurethane, and a water-based lubricant.
  • Wear cotton underwear.
  • Avoid sex until you've been evaluated.

See a doctor promptly if

• You have fever, pelvic pain, or ulcers.
• You are pregnant.
• You get four or more yeast infections a year.
• Symptoms don't improve with treatment.