The short answer: why yeast “takes over”

Your vagina has a delicate ecosystem made up of beneficial bacteria and small amounts of yeast. When the helpful bacteria drop or the environment changes (more moisture, higher sugar levels, hormone shifts), yeast can overgrow and cause symptoms.

1) Antibiotics (one of the biggest triggers)

Antibiotics can reduce the helpful bacteria that normally keep yeast under control. This is why yeast symptoms often show up during or right after a course of antibiotics.

Read next for a deeper breakdown:
Can Antibiotics Cause Vaginal Yeast Infections? (What to Do).

2) Hormonal changes (periods, pregnancy, birth control)

Hormone changes can shift vaginal pH and the balance of microbes. Many women notice yeast flares:

• Before their period
• During pregnancy
• After starting/changing birth control

If symptoms are recurring around your cycle, keep notes—patterns help you prevent the next one.

3) Moisture + friction (the “warm and tight” problem)

Yeast thrives in warm, moist conditions. Common contributors include:

• Staying in sweaty gym clothes for hours
• Tight, non-breathable leggings/underwear
• Wet swimsuits worn too long
• Friction during sex when tissue is irritated or dry

4) Blood sugar and diet (especially for frequent infections)

High blood sugar can support yeast growth, and some women notice symptoms worsen after high-sugar periods. If you get infections repeatedly, it’s worth looking at overall diet patterns.

If you want a symptom cross-check first, use:
Yeast Infection vs BV vs UTI: How to Tell the Difference.

5) Irritating products (soaps, douches, scented items)

Scented washes, bubble baths, and douching can irritate tissue and disrupt the natural balance. A good rule: keep it simple—warm water and gentle, unscented cleansing externally only.

Prevention checklist (simple + effective)

• Change out of sweaty clothes quickly
• Choose breathable cotton underwear
• Avoid douching and scented products
• Be cautious after antibiotics (support balance)
• Keep track of cycle-related patterns

For safe symptom relief ideas, see:
Natural Remedies for Yeast Infection in the Vagina That Actually Work.

FAQs

Can stress cause yeast infections in the vagina?

Stress can affect immunity and habits (sleep, diet), which may contribute for some people—especially if other triggers are present.

Can a yeast infection happen with good hygiene?

Yes. Yeast isn’t “dirt.” It’s usually about balance—hormones, antibiotics, moisture, and irritation.