Causes of vaginitis or vaginosis: how to tell them apart

Author: Jessica Lloyd
Senior Vulvovaginal Specialist Naturopath | BHSc(N) | ISSVD, ISSWSH, BSSM, ATMS

Last reviewed: July 2, 2026

If your vagina is itchy, sore, smelly or producing discharge that isn’t quite right, it’s tempting to reach for the yeast cream and hope. But plenty of different problems look and feel similar, and they need different treatments. Vaginitis (an irritated, inflamed vagina) and vaginosis (an out-of-balance one) are umbrella terms rather than specific diagnoses.

The three most common causes are bacterial vaginosis, a yeast infection (candida) and trichomoniasis. But the fuller list is long: aerobic vaginitis, cytolytic vaginosis, several sexually transmitted infections, allergies, skin conditions and even a urinary tract infection can all masquerade as ‘a vaginal infection’. Working out which one you actually have, ideally with a test, is what gets you sorted quickly instead of treating the wrong thing for months.

The three most common causes of vaginitis

When a cause is found, bacterial vaginosis accounts for roughly 40 to 50 per cent of cases, a yeast infection for about 20 to 25 per cent, and trichomoniasis for around 15 to 20 per cent. Non-infectious causes, like irritation and allergy, make up another 5 to 10 per cent.¹ So most of the time it’s one of the big three, but not always, and the big three don’t look identical.

Bacterial vaginosis (BV): thin, watery, greyish discharge with a fishy smell that’s often worse after sex. It comes from protective bacteria being crowded out by disruptive ones, which raises the vaginal pH and releases the amines behind that odour.^1,2
Yeast infection (candida): thick, white, cottage-cheese-like discharge, usually with itch and soreness but no strong smell. The pH stays normal.¹
Trichomoniasis: a sexually transmitted infection that can cause frothy, greenish or yellow discharge with a foul smell and irritation, though plenty of people have no symptoms at all.¹

How to tell them apart at a glance

None of this is a substitute for a proper diagnosis, but the standout sign is a useful starting point for narrowing down the type of vaginitis:

Fishy or foul smell: think BV first, then trichomoniasis or aerobic vaginitis.
Thick white discharge with itch, no smell: think candida, but if antifungals don’t work, think again (see below).
Burning, stinging or raw skin more than discharge: think irritation, allergy or a skin condition.
Pain when you wee, or needing to go constantly: think urinary tract infection.
Sores, blisters, lumps or pelvic pain: see someone in person for this one.

The microbiome imbalances

These are the ones that get muddled together most, because they all involve the vaginal ecosystem tipping out of balance, and they can look almost identical from the outside.

Bacterial vaginosis: the most common one, driven by a loss of protective lactobacilli and an overgrowth of disruptive bacteria such as Gardnerella vaginalis.²
Aerobic vaginitis (AV): a distinct type of imbalance involving different, more inflammatory bacteria, with redness, soreness and a yellowish discharge. It’s often mistaken for BV or yeast, but it’s its own thing and needs a different approach.³
Cytolytic vaginosis (CV): here the protective lactobacilli overgrow, so it looks exactly like a stubborn yeast infection, complete with thick white discharge and itch, but swabs are negative for candida and antifungals don’t help.⁴
Yeast infection: candida overgrowth, which can also become recurrent or resistant when the underlying terrain isn’t addressed.¹

Sexually transmitted infections

Several sexually transmitted infections (STIs) can cause discharge, irritation or urinary symptoms, and some are silent for long stretches. If there’s any chance one of these is in the picture, testing is the only way to know.

Trichomoniasis: frothy, foul-smelling, sometimes green discharge and irritation.
Chlamydia: often symptomless, but can bring frequent or burning urination, itching and discharge.
Gonorrhoea: smelly discharge and urethral symptoms, and again frequently silent.
Herpes simplex virus (HSV): sores, weeping, pain, itching and welts rather than discharge.
Genital warts from human papillomavirus (HPV): warts and local inflammation.
Pelvic inflammatory disease (PID): pelvic pain, aches and inflammation, often as a complication of an untreated STI. This one needs prompt medical care.

See the individual pages on sexually transmitted infections to check whether your symptoms fit.

Irritation, allergy and skin conditions

When the main feeling is burning, stinging or raw, sensitive skin rather than discharge, the cause is often not an infection at all.

Contact dermatitis: a reaction to perfumes, soaps, laundry detergents, wipes or pads, causing redness, swelling, itch, burning and sometimes discharge.
Latex, condom or semen allergy: pain, sensitivity, itching, swelling and inflammation, usually tied to sex.
Lichenoid skin conditions: including lichen simplex chronicus, lichen planus and lichen sclerosus. These are ongoing skin conditions of the vulva that cause itch, soreness and changes to the skin, and they need a proper in-person diagnosis.

Urinary tract infection

A urinary tract infection (UTI) is a urinary problem rather than a vaginal one, but it’s easy to lump in because it feels ‘down there’. The tell-tale signs are painful or burning urination and a constant urge to wee even when little comes out.

Why testing beats guessing

Because so many of these overlap, treating on a hunch is how people end up cycling through creams and antibiotics that never quite work. The most reliable way to know what you’re dealing with is to look at what’s actually growing.

A comprehensive vaginal microbiome test shows which bacteria and yeasts are present and in what proportions, which sorts BV from AV from cytolytic vaginosis from candida from a perfectly healthy result. From there, the options run the full range: conventional treatment where it’s warranted, plus rebuilding the protective bacteria, targeted botanicals, biofilm work and addressing the root drivers so the problem doesn’t just come back.

In our clinic, the commonest mix-up we see is a stubborn ‘yeast infection’ turns out to be cytolytic vaginosis, or BV is actually aerobic vaginitis – which is why testing beats guessing. Our free Killing BV guides cover the microbiome side, and if you want a plan matched to your own results you can book an appointment.

When to see someone in person

Some things need a physical examination, which we don’t do at My Vagina – we work with topical, acute and root-cause care, and point you to the right person for anything hands-on. See a doctor, sexual-health clinic or gynaecologist if you have:

sores, blisters, unusual lumps or bleeding
pelvic or lower-abdominal pain, or a fever
skin changes, splitting or whitening of the vulva
symptoms that don’t clear with the treatment you were given, or that keep coming back.

Frequently asked questions

Is it BV or a yeast infection?

This is the most common mix-up of the lot. Bacterial vaginosis brings thin, greyish discharge with a fishy smell and a raised pH, while a yeast infection brings thick, white, cottage-cheese-like discharge with itch and soreness, no real smell and a normal pH. If you’re not sure, or you’ve had both before, a swab or microbiome test settles it, and treating the wrong one just drags things out.

What’s the difference between vaginitis and vaginosis?

Roughly, ‘vaginitis’ means inflammation, with soreness, redness and irritation, while ‘vaginosis’ means an imbalance of the bacteria without much inflammation. In real life the words are used loosely and the two overlap, which is part of why a symptom alone won’t tell you the cause.

Can I have more than one at once?

Yes. It’s common to have, say, BV and candida together, or an imbalance sitting on top of an irritant reaction. That’s another reason a test that shows the whole picture is more useful than treating a single guess.

Why does my ‘yeast infection’ keep coming back or not respond to treatment?

If antifungals aren’t working, it may not be yeast. Aerobic vaginitis, cytolytic vaginosis and BV can all wear a yeast costume, and a non-albicans yeast can also shrug off the usual treatments. Fluconazole not working for a couple of weeks is itself a clue to get properly tested.⁴

Can I just treat it without a test?

For an occasional, textbook yeast infection, self-treatment is reasonable. But if it’s your first time, recurring, not clearing, or there’s any chance of an STI, testing first will save you time, money and frustration.¹

This is general information, not a substitute for personalised medical advice.

Paladine HL, Desai UA. Vaginitis: diagnosis and treatment. Am Fam Physician. 2018;97(5):321–329.
Coudray MS, Madhivanan P. Bacterial vaginosis – a brief synopsis of the literature. Eur J Obstet Gynecol Reprod Biol. 2020;245:143–148.
Donders GG, Vereecken A, Bosmans E, Dekeersmaecker A, Salembier G, Spitz B. Definition of a type of abnormal vaginal flora that is distinct from bacterial vaginosis: aerobic vaginitis. BJOG. 2002;109(1):34–43.
Suresh A, Rajesh A, Bhat RM, Rai Y. Cytolytic vaginosis: a review. Indian J Sex Transm Dis AIDS. 2009;30(1):48–50.