Slander or not, I am confused and very angry?

When I gave birth to my daughter I had marijuana in my system, it was not in her system. It was stupid I know. I had a safety plan put in place by DSS, which now the case is over and it was Unfounded. Some person I don't even know decides to tell my friend not to hang out with me because I did drugs and she knew all about my case. Is this slander or not?