It happens when the normal balance of microbes, including yeast and bacteria, in your vagina is thrown off. That means yeast can start to grow too much, causing itching, burning, and irritation. You might be more likely to get them if you’re taking antibiotics, you’re pregnant, you have uncontrolled diabetes, or a weakened immune system. Some birth control pills can cause them too. You can’t give a yeast infection to another person.