How can it be treated? With internal or external Canesten style? How to prevent it?

To treat a yeast infection in your partner, you can use an antifungal cream like Canesten™ 1%, applying it twice a day for 10 days on the affected area. It's important to make sure your partner does not have any known allergies before using this treatment. It's also important to practice safe sex and good hygiene to help prevent reinfection.