No - the Office on Women's Health is direct: it is not considered an STI because you can get one without having sex.
The cause is internal: Candida overgrowing when antibiotics, pregnancy, or uncontrolled diabetes shift the environment. The one nuance: partner transmission is possible, but it is the exception, and routine cases do not require treating a partner. The practical trap is the look-alike problem - yeast symptoms overlap with real STIs, so first, recurrent, or treatment-resistant symptoms deserve testing, not another tube of cream.
What to do
Common questions
Is a yeast infection an STI?
No. The Office on Women's Health answers it directly: a vaginal yeast infection is not considered an STI, because you can get one without having sex. The cause is internal - Candida, a fungus that normally lives in and on the body, overgrows when the environment shifts: antibiotics are the classic trigger, along with pregnancy, uncontrolled diabetes, and anything that changes vaginal acidity. The one sexual nuance OWH adds: it is possible to get a yeast infection from a sexual partner, and condoms and dental dams may help prevent passing one - but transmission is the exception, not the mechanism, and routine cases do not require treating a partner. The reason this classification matters practically is the look-alike trap: yeast symptoms - itching, burning, discharge - overlap with actual STIs and with bacterial vaginosis, and OWH warns that assuming "yeast" when it is something more serious lets real infections run untreated. First episode, recurrent episodes, or symptoms that survive over-the-counter treatment: get tested instead of re-treating. Pymander, a free AI doctor available 24/7 by text, can help you tell the patterns apart.