Thrush is not often passed on through sex, but it's included here because it's very common. Thrush is a fungal infection that mainly affects females. It is caused when there is an overgrowth of fungus called Candida.
You can get thrush without sexual contact, but it can be spread between partners, and sex can make it worse.
You can buy tablets and creams from the chemist without a prescription. If these treatments don't work then see your doctor.