Any hormone, or even over the counter drug such as Tylenol can incur negative side effects if used improperly. This should not even be a question, when it should be plain obvious.
I know of one person who picked up chirrhosis of the liver just from over the counter sleeping pills, using them every day for about 3 years. I also know someone who wasn't yet 30 who died from having a couple drinks daily, not everyones liver is the same and when you don't know what you are doing to YOUR body problems can happen. Not everyone was built the same, not everyone can take the same drug regimen and not everyone responds the same.
This is why medicine is PRACTICED.
Birth control is not the same for all women either.
Even ONE drink of alcohol incurs side effects in the body, however undetectable to the outside world.