Hello,
Thanks for your consult at DoctorSpring.com.
Plan B is an emergency contraceptive pill. It is used for ' morning - after ' emergency contraception in case of regular contraceptive failure / unexpected unprotected sexual intercourse.
IN NO WAY can it be used to treat UTI or a yeast infection. For UTI, a proper urine examination is essential to pinpoint the offending organism.
Based on the organism isolated, culture specific antibiotics are required. For yeast infections, antifungals ( systemic or local ) are prescribed.
Hope this helps, please feel free to discuss further.
All the best