Making a doll that looks like some one and sticking pins in them to hurt them doesn't not work, but that isn't voodoo magic either.
Voodoo magic based on the ancient African traditions mixed with Christan influences during the time of slavery, does exist and is very real and can be very useful. Real Voodoo dolls are used in healing magic and rituals and are made to mimic yourself for self healing exercises. In you are interested in Voodoo magic they are a good start for beginners.
voodoo is a religion, hoodoo is magi ck, and hoodoo works about as well as Navajo skin walking, only when its dark, vague, and there's bones, psychoactive drugs, energy control, and nudity
Here's what a medical book I read said about one case:
This one man came in. He was dying, but after a whole battery of tests, they could find absolutely no reason that he should be dying at all. The doctor was puzzled. He asked the man what he thought was wrong with him. The man said that he was the victim of voodoo and that he had angered the medicine man of his village. The doctor decided to lie to the patient to help him. He told the man that he was sick because there were lizards crawling in his stomach. He gave the patient something that would make him throw up to "get rid of the lizards". The man threw up and when he wasn't looking the doctor quickly slipped in a lizard into the bucket. The man immediately got better and was able to return home. It was the conclusion of the doctor, and me that voodoo is purely psychological.