**Neither a urinary tract infection nor a vaginal yeast infection is contagious the way a cold or the flu is, though yeast can sometimes pass between sexual partners.**
Both start with organisms that already live in or on your body rather than something you catch from another person. A UTI happens when gut bacteria such as E. coli reach the urethra and bladder, which is why sex, wiping habits, and holding urine matter more than exposure to someone else. A yeast infection happens when Candida, a fungus normally present in small amounts, overgrows after antibiotics, during pregnancy, or when blood sugar runs high. Yeast can occasionally transfer during sex and cause itching or a rash in a partner, but partners usually do not need treatment. Since burning and discharge overlap between the two, and since some sexually transmitted infections look similar, testing is what tells them apart.
Sorting out which one it is
Common questions
Is uti vs yeast contagious?
UTIs are not spread person to person. They start when bacteria that already live on your skin or in your gut reach the urethra and bladder, so sex can trigger one without passing an infection to a partner. Vaginal yeast infections come from Candida, a fungus that normally lives in the body and overgrows after antibiotics, during pregnancy, or when diabetes is poorly controlled. Yeast can occasionally transfer during sex and cause irritation or a rash in a partner, but that is uncommon and partners rarely need treatment. Neither infection spreads through toilet seats, towels, swimming pools, or hot tubs. Repeat symptoms, or symptoms with a new partner, are worth testing because chlamydia, gonorrhea, and trichomoniasis can feel similar.