Why do i always get a yeast infection or bladder infection after i have already taken antibiotics?

Good bac. Destroyed : Whenever a patient takes antibiotics, they're killing good and bad bacteria. Most likely, you are destroying your good bacteria and decrease the shielding effect against unwanted organisms, that includes bad bacteria, fungus(yeast), and viruses.

Normal Flora: Each area of the body, including the vagina, has it's own normal flora, including bacteria and yeast. Usually they are in balance with each other. When treated with antibiotics for an infection the medicine targets one type of organism - the bacteria. This gives the yeast a chance to take over and you then get a yeast infection or overgrowth. This is a very common side effect of antibiotics.

Try probiotics: Try some oral probiotics (available at most pharmacies over-the-counter) to restore your "natural flora" of microbes. Certain varieties of yogurt have helpful probiotics. Some doctors also recommend using probiotics vaginally to help restore one's vaginal flora. Check with an Ob-Gyn doctor for a more specific recommendation based on what's available in your local area.