References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Candida is a type of yeast (fungus) that naturally lives on the skin and in the body, including the vagina, mouth and gut. In small amounts it’s harmless, but when conditions allow it to overgrow, it causes thrush (candidiasis). Candida overgrowth is treated with antifungal medication and prevented by maintaining the body’s natural balance.
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Types of Candida Infection
| Site | Condition |
|---|---|
| Vagina | Vaginal thrush |
| Penis | Penile thrush / balanitis |
| Mouth | Oral thrush |
| Skin folds | Cutaneous candidiasis |
| Nappy area | Nappy rash |
What Causes Overgrowth
- Antibiotics
- Diabetes
- Immune suppression
- Hormonal changes
- Moisture and warmth
Treatment
- Fluconazole tablet
- Clotrimazole cream or pessary
- Nystatin for oral thrush
Is Thrush an STI?
Not usually — it’s a natural yeast overgrowth. Occasionally passed between partners but not classed as an STI.
Read more: What is thrush? | Fluconazole | Balanitis
Frequently Asked Questions
Is candida always harmful?
No — small amounts are normal. Only overgrowth causes problems.
Can men get thrush?
Yes — penile thrush is common.
Is thrush contagious?
Occasionally between partners but not classified as an STI.
Related reading
- Can You Test for STIs While on Your Period?
- Common STI Symptoms in Women
- Does a Vaginal Yeast Infection Smell?
- HIV Risk from Vaginal Sex: What You Need to Know
- How Different STIs Affect Vaginal Discharge
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
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