If i had a bleeding week with period symptoms a few days after taking plan b. does that mean i am not pregnant? how can i know if it was a side effec

Unlikely pregnant: If you've had a period-like bleed after taking Plan B then you're unlikely to be pregnant and the medication worked. Plan B gives you a large dose of progesterone, which after exposure, can induce a period. This usually happens if you've already ovulated and your body was ready to have a period anyway, but the Plan B just helped that process.