STIs vs Thrush vs BV: How to Tell What's Really Going On

When Symptoms Overlap: The Diagnostic Challenge

If you're experiencing unusual discharge, itching, or discomfort, you might be wondering: is this thrush, bacterial vaginosis (BV), or could it be a sexually transmitted infection?

You're not alone in this confusion. These conditions share many symptoms, and even healthcare professionals sometimes need tests to distinguish between them. Let's break down each condition and help you understand what might be happening.

Understanding the Three Main Culprits

Thrush (Vaginal Candidiasis)

What it is: A yeast infection caused by an overgrowth of *Candida* fungus, most commonly *Candida albicans*.

Key characteristics:

• Not sexually transmitted – though sex can sometimes trigger it
• Caused by disruption to the normal vaginal environment
• Very common – about 75% of women will experience it at least once

Classic symptoms:

• Thick, white discharge (often described as "cottage cheese-like")
• Intense itching and irritation
• Redness and swelling of the vulva
• Burning sensation, especially during urination or sex
• Discharge usually has no strong odour

Common triggers:

• Antibiotics (disrupt normal bacterial balance)
• Hormonal changes (pregnancy, periods, contraceptives)
• Diabetes (elevated sugar feeds yeast)
• Weakened immune system
• Tight or non-breathable clothing
• Perfumed products near the vagina

Bacterial Vaginosis (BV)

What it is: An imbalance in the vaginal bacteria, where the normal protective *Lactobacillus* bacteria are replaced by other organisms, particularly *Gardnerella vaginalis*.

Key characteristics:

• Not classified as an STI – though sexual activity can trigger it
• The most common cause of vaginal discharge in women of childbearing age
• Can occur in women who aren't sexually active, though less commonly

Classic symptoms:

• Thin, watery, greyish-white discharge
• Strong "fishy" odour, especially after sex or during periods
• Usually no itching or irritation (key difference from thrush)
• May have no symptoms at all (up to 50% of cases)

Risk factors:

• New or multiple sexual partners
• Douching or vaginal washing
• Not using condoms
• Having a female sexual partner
• IUD contraception

Sexually Transmitted Infections

Several STIs can cause similar symptoms:

Chlamydia:

• Often no symptoms (70% of cases)
• When present: unusual discharge, bleeding between periods, pelvic pain
• Discharge may be yellowish

Gonorrhoea:

• May cause increased discharge (often yellow or green)
• Pain when urinating
• Bleeding between periods
• Often has no symptoms in women

Trichomoniasis:

• Frothy, yellow-green discharge with strong odour
• Itching and irritation
• Pain during sex or urination
• Vulval redness

Herpes:

• Painful sores or blisters
• Tingling or burning before outbreak
• Flu-like symptoms during first outbreak
• May cause unusual discharge

Side-by-Side Comparison

Why Self-Diagnosis Is Risky

While these comparisons are helpful, self-diagnosis has significant limitations:

Symptoms Overlap Significantly

• You might have thrush AND an STI simultaneously
• BV and trichomoniasis symptoms are very similar
• Some STIs cause no symptoms at all

Incorrect Treatment Can Cause Harm

• Using thrush treatments when you have BV can worsen the imbalance
• Delaying STI treatment allows complications to develop
• Over-the-counter products don't treat STIs

STIs Have Serious Consequences

• Untreated chlamydia and gonorrhoea can cause infertility
• STIs increase HIV transmission risk
• Infections can be passed to partners unknowingly

When to Get Tested

You should seek testing rather than self-treating if:

This Is Your First Episode

• Don't assume it's thrush if you've never had confirmed thrush before
• First episodes need proper diagnosis

Symptoms Are Different From Usual

• If you've had thrush before but this feels different
• New symptoms like fishy odour, unusual discharge colour, or sores

Treatment Hasn't Worked

• If over-the-counter thrush treatment hasn't resolved symptoms within a week
• Recurring symptoms (more than 2 episodes in 6 months)

You Have Risk Factors for STIs

• New sexual partner
• Unprotected sex
• Partner with known STI
• Multiple partners

Additional Symptoms Are Present

• Pelvic pain
• Bleeding between periods or after sex
• Fever
• Sores, blisters, or unusual lumps

Getting Tested: What to Expect

Testing typically involves:

For STIs

• Swab tests – from vagina, cervix, throat, or rectum depending on sexual history
• Urine sample – for chlamydia and gonorrhoea
• Blood tests – for HIV, syphilis, hepatitis B

For BV and Thrush

• Vaginal swab – examined under microscope or sent to lab
• pH testing – BV typically causes elevated vaginal pH (above 4.5)

Many sexual health clinics can test for all these conditions in one visit.

Treatment Overview

Thrush Treatment

• Antifungal pessaries (inserted vaginally) – e.g., clotrimazole
• Oral antifungals – e.g., fluconazole (single dose)
• Topical creams – for external symptoms
• Available over the counter once you've had a confirmed diagnosis

BV Treatment

• Antibiotics – metronidazole (tablets or gel) or clindamycin
• Requires prescription – cannot be treated with thrush medications
• Partners generally don't need treatment (unless symptoms present)

STI Treatment

• Chlamydia: Antibiotics (usually doxycycline or azithromycin)
• Gonorrhoea: Antibiotic injection (ceftriaxone)
• Trichomoniasis: Metronidazole
• Partners MUST be treated to prevent re-infection

Prevention Strategies

General Vaginal Health

• Avoid douching or vaginal deodorants
• Wear breathable cotton underwear
• Wipe front to back after using the toilet
• Change out of wet swimwear promptly
• Use unperfumed soaps and avoid products inside the vagina

Preventing BV Recurrence

• Consider probiotics (evidence is emerging but promising)
• Avoid douching
• Use condoms with new partners
• Discuss prevention strategies with your clinician

Preventing STIs

• Use condoms consistently
• Get tested with new partners
• Discuss sexual health openly
• Regular screening if you have multiple partners

The Bottom Line

Unusual vaginal symptoms deserve proper attention – not guesswork. While thrush is common and often recognisable, the overlap with BV and STIs means testing is often the safest approach.

Don't let embarrassment prevent you from getting checked. Sexual health clinicians see these conditions daily and are there to help without judgement.

Get Clarity Today

If you're experiencing symptoms and aren't sure what's causing them, get tested. Our comprehensive screening covers STIs and can help you understand exactly what's happening. Book your confidential test today.