Vaginal Health And Periods: What's Normal And What's Not

Periods are normal but so is a little worry about what happens “down there” when bleeding shows up each month. The good news: for most people, menstrual bleeding produces transient, predictable changes to the vagina that are part of normal physiology. But in some situations bleeding can create conditions that raise the risk of symptoms or infections and those need attention. Here we discuss common vaginal changes that occur during periods and which are normal and which may need medical attention.

Why periods change the vaginal environment

Oestrogen levels fall in the days leading to and during bleeding. Oestrogen normally helps vaginal cells store glycogen, which beneficial Lactobacillus bacteria feed on. When oestrogen falls, Lactobacillus numbers often dip, and the overall bacterial community becomes more diverse. Several longitudinal studies show increased vaginal microbial diversity during menses with a corresponding drop in dominant lactobacilli.

Along with this, blood raises vaginal pH (makes it less acidic) and brings iron and other nutrients that can alter growth conditions for microbes. A less acidic environment and extra nutrients can temporarily favour the growth of a wider range of bacteria or yeasts. That shift is usually short-lived but explains why many people notice changes while they bleed.

What changes are common and normal during periods

1. Slightly different discharge: Blood mixes with normal secretions so you may see more volume, a darker colour or a slightly stronger smell while bleeding. This is expected.
2. Mild odour: A faint “metallic” or menstrual smell is normal when blood is present. It shouldn't be overpowering or fishy.
3. Temporary increase in microbial diversity: Studies that took daily swabs show a fall in Lactobacillus and higher diversity during menses, but most women's microbiota returns to its pre-period state after bleeding stops.
4. Minor itching or irritation: Occasional mild itch or discomfort from rubbing, pads or tampons is common. It usually resolves once you change products or stop bleeding. These are normal if they are mild, do not worsen over days, and are not accompanied by severe pain or fever.

What's not normal and when to worry

1. Strong fishy odour: Classic for bacterial vaginosis (BV), which has been linked to periods because menstrual conditions can temporarily favour BV-associated bacteria. Persistent fishy smell should be assessed.
2. Severe itching, burning, or painful urination: Could be yeast infection (candida) or urinary tract infection.
3. Pelvic pain, fever, very heavy bleeding, or foul-smelling discharge: Could indicate pelvic infection or complication, seek urgent care.
4. Bleeding between periods or after sex: Needs evaluation; not a typical menstrual change.

Are periods linked to higher infection risk?

Periods can temporarily create conditions (higher pH, lower Lactobacillus, blood as nutrient source) that may increase susceptibility to certain problems. For example, transient increases in bacteria associated with BV have been observed during menses in multiple studies. That doesn't mean everyone will get BV; it means the risk window is slightly larger for those who already have risk factors such as douching, multiple partners, smoking, etc.

How to keep your vaginal health steady during periods

• Change pads/tampons/menstrual cups regularly (follow manufacturer guidance). Don't leave tampons in too long.
• Use plain water to clean externally; avoid douching or scented washes, these disrupt the protective microbiota.
• Choose breathable cotton underwear and change if wet.
• If you use reusable products, wash and dry them per instructions and store dry. Studies show hygiene practices influence BV prevalence in some settings.
• Watch for red flags listed above and consult a healthcare provider if they appear. Early treatment of BV, yeast infection, or STI reduces complications.

Periods do change the vaginal environment, hormonally and physically and those changes commonly produce short-lived shifts in smell, discharge and microbiome composition. For most people these are harmless and reverse after menses. But if you notice strong odour, abnormal-colour discharge, severe pain, fever or heavy bleeding, get evaluated. Simple hygiene measures and sensible menstrual-product use reduce risk for most common problems.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your doctor for more information. NDTV does not claim responsibility for this information.

References

Daily Vaginal Microbiota Fluctuations Associated with Natural Menstrual Cycle — mSphere : American Society for Microbiology (ASM) — 2020.

The healthy female microbiome across body sites: effect of the menstrual cycle — NCBI — 2022.

The Female Vaginal Microbiome in Health and Bacterial Vaginosis — (review article) : NCBI — 2021.

Analysis of bacterial vaginosis, the vaginal microbiome, and menstrual product use (CaCHe study / related trials) — (clinical study) : NCBI— 2023.

Bacterial Vaginosis — StatPearls — StatPearls — 2024.