Here is a recipe for a safe and inexpensive way to keep your drains clear and or unclog them as necessary. I have used it for years and it WORKS!!
1 cup baking soda
1 cup white vinegar
Pour the baking soda in the drain followed by the vinegar. Allow it to fizz for 20 minutes or so and then rinse with hot water.
I also do this to the shower heads when they start to clog.