When the pimple is popped, the pus typically has a white or yellow tint. But sometimes, you’re met with green. “A green discoloration may be the result of a specific type of bacteria involved in an infection, but that usually is not the case in acne,” Dr. Zeichner says. While normal bacteria-causing acne will not result in this, if you do have a big, painful, green-filled pustule, ask your doctor whether you might need a prescription for antibiotics.